JP2013239358A - Nonaqueous electrolyte secondary battery anode, nonaqueous electrolyte secondary battery, nonaqueous electrolyte secondary battery system, and manufacturing method thereof - Google Patents

Abstract

Provided is a long-life nonaqueous electrolyte secondary battery in which the capacity retention rate does not decrease even during charge / discharge cycles.
A negative electrode for a non-aqueous electrolyte secondary battery having a negative electrode mixture layer formed on a negative electrode current collector, wherein the negative electrode mixture layer includes negative electrode active material particles, and the negative electrode active material particles are carbon. The negative electrode mixture layer is made of a material, and the negative electrode active material particle layer has a layer with a long diameter / short diameter high and a layer with a long diameter / low short diameter, and the negative electrode active material particle has a long diameter / short diameter. The major axis / minor axis of the negative electrode active material particles contained in the higher layer is larger than the major axis / minor axis of the negative electrode active material particles contained in the lower layer of the major axis / minor axis of the negative electrode active material particles. In the inward direction, a layer having a large major axis / minor axis of the negative electrode active material particle is formed between layers having a large major axis / minor axis of the negative electrode active material particle, and is included in a layer having a large major axis / minor axis of the negative electrode active material particle. A negative electrode for a nonaqueous electrolyte secondary battery in which the direction of the major axis of the negative electrode active material particles is arranged in parallel with the negative electrode current collector.
[Selection] Figure 1

Description

  The present invention relates to a negative electrode for a non-aqueous electrolyte secondary battery, a non-aqueous electrolyte secondary battery, a non-aqueous electrolyte secondary battery system, and methods for producing them.

  Secondary batteries such as lithium ion secondary batteries are attracting attention as batteries for electric vehicles and power storage from the viewpoint of environmental problems. It is lighter than lead batteries and nickel cadmium batteries, and has characteristics such as high output and high energy density, and is expected in the near future.

  However, conventional lithium ion batteries are required to further improve battery characteristics. For example, further increase in capacity is desired in order to increase the travel distance of electric vehicles.

  Here, the negative electrode which is the subject of the present invention includes an active material capable of inserting and releasing lithium ions, a conductive agent and polyvinylidene fluoride (PVDF) system, and styrene butadiene rubber (SBR). A negative electrode slurry prepared, mixed, and stirred with a binder such as the above is attached to a current collector sheet such as copper by the doctor blade method, etc., and then heated to dry the organic solvent or water and roll press Can be produced by pressure molding. At this time, the active material density is increased by filling with more active material and press-molding, thereby enabling higher capacity. In addition, as carbon materials used for the negative electrode active material, various carbon materials such as high crystalline graphite to low crystalline graphite, non-crystalline graphite, artificial graphite, coated natural graphite, and hard carbon have been studied. Yes. Active materials that can be increased in capacity are almost soft. For example, when natural graphite, artificial graphite, soft carbon, or highly crystalline graphite is used, as a result of pressure molding with a roll press, the active material is found to be active according to SEM observation and X-ray diffraction. The material was deformed to extend in the horizontal direction with the current collector, causing the problem of orientation of the basal plane. Li ions repeatedly move between the positive and negative electrodes in the direction perpendicular to the electrodes during charging and discharging of the battery. When the active material orients the basal plane, the edge plane is oriented perpendicular to the current collector, so that the path for Li ions to detour becomes long and the rate characteristics are degraded. In addition, once pressure molding is performed at the same surface pressure in the pressing process, stress tends to remain in the mixture layer, and the mixture layer is cracked due to the volume change of the active material due to the charge / discharge cycle of the battery. The possibility of peeling / dropping from the body and the binding between the active material particles is increased.

  In Patent Document 1, a convex portion is formed on the surface of the mixture layer, and by simultaneously pressurizing the convex portion and the mixture layer, the particles of the convex portion sink into the mixture layer, and the surface of the mixture layer becomes smooth. A concave portion is formed on the surface of the current collector by the pressure, and the density of the mixture layer located on the upper portion of the concave portion of the current collector is increased. Thus, a technique for improving the adhesion between the mixture layer and the current collector is disclosed.

  In Patent Document 2, a roller having a plurality of convex portions formed on the surface is disposed on the negative electrode plate, and the roller is rotated and moved while pressing the surface of the negative electrode plate. A technique having a step of forming a groove is disclosed.

JP 2010-250994 A Japanese Patent No. 4362544

  However, Patent Document 1 is a two-stage coating, which takes twice as long as coating and drying, and is considered undesirable from the viewpoint of cost reduction. In Patent Document 2, since the mixture layer formed on the current collector was pressed by a roller having a smooth surface before groove processing of the mixture layer, the stress acting on the negative electrode mixture layer could not be relieved, and charge / discharge Crack extension due to cycling may occur.

  An object of this invention is to relieve | moderate the stress which acts on a negative mix layer.

  The problem to be solved by the present invention is solved by the following means, for example.

  A negative electrode for a nonaqueous electrolyte secondary battery having a negative electrode mixture layer formed on a negative electrode current collector, the negative electrode mixture layer containing negative electrode active material particles, the negative electrode active material particles containing a carbon material, The negative electrode mixture layer has a layer having a large major axis / minor axis of the negative electrode active material particles and a layer having a long major axis / minor axis of the negative electrode active material particles, and a layer having a large major axis / minor axis of the negative electrode active material particles. The major axis / minor axis of the negative electrode active material particles contained is larger than the major axis / minor axis of the negative electrode active material particles contained in the lower layer of the major axis / minor axis of the negative electrode active material particles, and in the in-plane direction of the negative electrode current collector, Negative electrode active material particles in which a layer having a long major axis / short minor axis is formed between layers having a long major axis / short minor axis of negative electrode active material particles, and a layer having a long major axis / short minor axis is formed. A negative electrode for a non-aqueous electrolyte secondary battery in which the direction of the major axis is arranged in parallel with the negative electrode current collector.

  In the above, irregularities are formed on the surface of the negative electrode mixture layer, a layer having a larger major axis / minor axis of the negative electrode active material particles is formed in the concave portion of the negative electrode mixture layer, and the negative electrode active material particles are formed on the convex portion of the negative electrode mixture layer A negative electrode for a non-aqueous electrolyte secondary battery in which a layer having a long / short diameter is formed.

  In the above, the peak intensity ratio {I (110) / I (004)} from the carbon material obtained by X-ray diffraction of the layer having the long axis / low axis of the negative electrode active material particles is 0.1 or more and 0.5 or less. A negative electrode for a non-aqueous electrolyte secondary battery.

  In the above, in the in-plane direction of the negative electrode current collector, the negative electrode active material particle high-major axis / minor axis layer is a negative electrode for a nonaqueous electrolyte secondary battery formed in a dot shape, a linear shape, or a lattice shape.

  In the above, the negative electrode for a non-aqueous electrolyte secondary battery in which the composition of the layer having a long / short diameter of the negative electrode active material particles and the layer having a low long / short diameter of the negative electrode active material particles are the same.

  In the above, the negative electrode for nonaqueous electrolyte secondary batteries in which a thickener is contained in the negative electrode mixture layer.

  A nonaqueous electrolyte secondary battery using the above negative electrode for a nonaqueous electrolyte secondary battery.

  A non-aqueous electrolyte secondary battery system using a plurality of the above non-aqueous electrolyte secondary batteries.

  A method for producing a negative electrode for a nonaqueous electrolyte secondary battery having a negative electrode mixture layer formed on a negative electrode current collector, wherein the negative electrode mixture layer includes negative electrode active material particles, and the negative electrode active material particles are carbon materials. The negative electrode mixture layer has a layer having a long axis / short axis of the negative electrode active material particles and a layer having a long axis / low short axis of the negative electrode active material particles, and has a long axis / short diameter of the negative electrode active material particles. The major axis / minor axis of the negative electrode active material particles contained in the higher layer is larger than the major axis / minor axis of the negative electrode active material particles contained in the lower layer of the major axis / minor axis of the negative electrode active material particles, and the in-plane of the negative electrode current collector In the direction, a negative electrode active material particle layer is formed with a press roller in which a layer having a long major axis / minor minor axis is formed between layers having a large major axis / minor major axis of the negative electrode active material particle and a plurality of convex portions are formed. The step of forming a layer with a large major axis / minor axis of the negative electrode active material particles by pressing, and the negative electrode combined with a press roller having a smooth surface A step of pressing the layer so that the direction of the major axis of the negative electrode active material particles contained in the layer having a larger major axis / minor axis of the negative electrode active material particles is parallel to the negative electrode current collector. Manufacturing method of negative electrode.

  In the above, by pressing the negative electrode mixture layer with a press roller having a smooth surface, the peak intensity ratio {I (110 ) / I (004)} is 0.1 or more and 0.5 or less, and the manufacturing method of the negative electrode for nonaqueous electrolyte secondary batteries.

  According to said structure, the stress which acts on a negative mix layer can be relieve | moderated. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

It is sectional drawing of a negative electrode. It is sectional drawing of the coin-type lithium ion battery which concerns on one Embodiment of this invention. It is a top view of an anode concerning one embodiment of the present invention, and a sectional view of AA '. It is a top view of a negative electrode concerning one embodiment of the present invention, and a sectional view of BB '. It is the top view and CC 'sectional drawing of the negative electrode which concern on one Embodiment of this invention. 1 is a structural diagram of a cylindrical lithium ion battery according to an embodiment of the present invention. It is a battery module which consists of a cylindrical lithium ion battery concerning one embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following examples show specific examples of the contents of the present invention, and the present invention is not limited to these examples, but by those skilled in the art within the scope of the technical idea disclosed in this specification. Various changes and modifications are possible. Further, in all the drawings for explaining the embodiments, the same reference numerals are given to those having the same function, and repeated explanation thereof is omitted.
A nonaqueous electrolyte secondary battery according to an embodiment of the present invention includes a positive electrode and a negative electrode capable of inserting and removing lithium ions, a separator separating the positive electrode and the negative electrode, and an electrolyte. Hereinafter, these elements will be described. In addition to lithium ions, positive and negative electrodes capable of inserting and removing magnesium ions and sodium ions may be used. Below, a lithium ion secondary battery is demonstrated.

<Negative electrode>
FIG. 1 is a cross-sectional view of the negative electrode 101. In one embodiment of the present invention, a negative electrode for a non-aqueous electrolyte secondary battery having a negative electrode mixture layer 105 formed on a negative electrode current collector 104, wherein the negative electrode mixture layer 105 includes a negative electrode active material, A surface of the negative electrode current collector 104, which includes an optional conductive assistant and an optional binder, and has a layer 102 with a large major axis / minor axis of negative electrode active material particles and a layer 103 with a long major axis / minor axis of negative electrode active material particles. In the inward direction, a layer 102 having a large major axis / minor axis of the negative electrode active material particle is formed between the layers 103 having a long major axis / minor axis of the negative electrode active material particle, and a layer 102 having a large major axis / minor axis of the negative electrode active material particle. The major axis direction of the negative electrode active material particles contained in is arranged substantially parallel to the negative electrode current collector 104. At this time, the major axis / minor axis of the negative electrode active material particles contained in the layer 102 having a long major axis / minor axis of the negative electrode active material particles is equal to the negative electrode active material particles contained in the layer 103 having a major axis / low minor axis of the negative electrode active material particles. Larger than the major axis / minor axis. Thereby, the stress which acts on the negative mix layer 105 can be relieved, and the crack extension by a charging / discharging cycle can be suppressed. The term “substantially parallel” means that the angle between the direction of the major axis of the negative electrode active material particles contained in the layer 102 having a larger major axis / minor axis of the negative electrode active material particles and the negative electrode current collector 104 is 130 to 180 degrees.

  The difference between the negative electrode active material particle long axis / short axis high layer 102 and the negative electrode active material particle long axis / low short axis layer 103 can be determined by the scanning electron microscope (SEM) of the cross-sectional state of the negative electrode mixture layer 105. . When investigating the major axis / minor axis of the negative electrode active material particles more precisely, the particle shape of the active material can be analyzed from the photographed SEM photograph using known image processing software. It is desirable that the image processing software applied to the present invention has an application capable of automatically separating and recognizing the particles on the image one by one and measuring the area of the particles. Further, it is more desirable to have a function capable of measuring the major and minor diameters of the area and the number of particles. It is further desirable to have a function of automatically converting the area of each particle to the volume.

  Similarly, the direction of the long axis of the layer 102 having a long diameter / high short diameter of the negative electrode active material particles can be observed by SEM. By using the above image processing, more precise data can be obtained.

  The negative electrode mixture layer 105 applied on the negative electrode current collector 104 is first pressed with a press roller having a plurality of convex portions formed on the surface in a pressing step, and the negative electrode active material particles have a long major axis / short minor axis layer. 102 is obtained. At this time, a concave portion is formed in a portion of the negative electrode mixture layer 105 corresponding to the layer 102 having a larger major axis / minor minor axis of the negative electrode active material particles. Next, the whole negative electrode mixture layer 105 is pressed by a press roller having a smooth surface at a pressure smaller than the press pressure when pressing with a press roller having a convex portion. The layer 102 having a large major axis / minor axis of the negative electrode active material particles tends to be crushed at a higher surface pressure than the layer 103 having a small major axis / minor axis of the negative electrode active material particles. For this reason, the layer 102 having a large major axis / minor axis of the negative electrode active material particles has a longer axis direction of the negative electrode active material particles substantially parallel to the negative electrode current collector 104, and has better adhesion to the negative electrode current collector 104. Get higher. This serves as an anchor ring when the volume of the negative electrode active material is changed by the charge / discharge cycle.

  In one embodiment of the present invention, the peak intensity ratio {I (110) / I (1) from the carbon material obtained by X-ray diffraction of the layer 103 having a long major axis / low minor axis of the negative electrode active material layer 105 of the negative electrode mixture layer 105 is low. 004)} is preferably 0.1 or more and 0.5 or less. Thereby, it can be determined that the negative electrode active material particles are not crushed and the basal plane orientation is suppressed.

  In one embodiment of the present invention, in the in-plane direction of the negative electrode current collector 104, the layer 102 having a long major axis / short minor axis of the negative electrode active material particles is formed in any one of a dot shape, a linear shape, and a lattice shape. It is desirable. Thereby, the stress of the negative mix layer 105 can be relieved and the crack extension by a charging / discharging cycle can be suppressed. Even if there are surface irregularities that occur between the layer 102 with the long / short diameter of the negative electrode active material particles and the layer 103 with the long / short diameter of the negative electrode active material particles, the negative electrode 101 has little trouble in performance. In this case, the impregnating property of the electrolytic solution due to the unevenness on the surface of the negative electrode mixture layer 105 can be improved. Further, when the lithium metal dissolution and precipitation reaction is repeated, Li dendrite grows, causing an internal short circuit between the positive electrode and the negative electrode, and the safety of the battery may be lost. Li dendrite precipitation can be suppressed by the surface unevenness generated between the layer 102 having a large major axis / minor axis of the negative electrode active material particles and the layer 103 having a small major axis / minor axis of the negative electrode active material particles. Thereby, a quick charge response | compatibility is attained.

  In one embodiment of the present invention, it is desirable that the composition of the negative electrode active material particle layer 102 having a long diameter / short diameter high layer and the negative electrode active material particle layer 103 having a long diameter / low short diameter be the same. The composition is the same as the material constituting the layer 102 of the negative electrode active material particles having the long diameter / short diameter high (active material, conductive agent, binder) and the material forming the layer 103 of the negative electrode active material particles having the long diameter / short diameter low. Say everything is the same. As a result, it is possible to reduce the manufacturing cost by coating once. As for capital investment, only the number of press rolls increases, and the manufacturing time hardly increases.

  In one embodiment of the present invention, the negative electrode mixture layer 105 preferably contains a thickener. Thereby, smooth application | coating can be performed at the coating process at the time of negative electrode manufacture, and the malfunction of a coating surface can be prevented.

  As the negative electrode active material according to an embodiment of the present invention, graphite or amorphous carbon capable of electrochemically occluding and releasing lithium ions can be used. There are no restrictions on types or materials. Since the negative electrode active material to be used is generally used in a powder state, the binder is mixed to bond the powders together, and at the same time, the layer made of the negative electrode active material is bonded to the negative electrode current collector as a mixture layer I am letting.

  The negative electrode active material includes a carbon material capable of occluding and releasing lithium ions. For example, natural graphite, artificial graphite, amorphous carbon, or the like can be used. Coated natural graphite to reduce irreversible capacity is more desirable. The above materials may be used alone or in combination of two or more. In one embodiment of the present invention, it is desirable to use graphite as the negative electrode active material. This is because, when graphite is used as the negative electrode active material, the Coulomb efficiency (initial discharge electricity amount / charge electricity amount) is high, so that a high capacity can be obtained, and the electric potential is low and the flat discharge characteristics are obtained. This is because a high output battery can be expected.

  The conductive assistant has conductivity and does not substantially store lithium ions, but coke, carbon black, acetylene black, carbon fiber, ketjen black, carbon nanotube, mesocarbon microbead, vapor grown carbon fiber, etc. The carbon material may be used.

  As the binder, in addition to polyvinylidene fluoride (PVDF), a fluorine-based polymer such as polytetrafluoroethylene, styrene butadiene rubber (SBR), acrylonitrile rubber, or the like may be used. Other binders not listed above may be used as long as they do not decompose at the reduction potential of the negative electrode and do not react with the nonaqueous electrolyte or the solvent in which it is dissolved. A known solvent suitable for the binder may be used as the solvent used for preparing the negative electrode slurry. For example, a known solvent such as water in the case of SBR, acetone, toluene or the like can be used in the case of PVDF. The binder content in the negative electrode mixture layer is preferably 0.5 wt% or more and 2.0 wt% or less. If the binder content is greater than 2.0 wt%, the internal resistance may increase.

  A thickener can also be used to adjust the viscosity of the slurry. For example, carboxymethyl cellulose (CMC) can be used for SBR. Examples of the thickener include PVP, PEO, AQUPEC and the like in addition to CMC. As the thickener, the above materials may be used alone or in combination of two or more.

  The negative electrode current collector is required to be made of a material that is difficult to be alloyed with lithium, and there is a metal foil made of copper, nickel, titanium, or an alloy thereof. In particular, copper foil is frequently used.

  The negative electrode is made by adhering a negative electrode slurry mixed with a negative electrode active material, a conductive agent, a binder, and an organic solvent to the negative electrode current collector by a doctor blade method or the like, and then heating to dry the organic solvent. It can be produced by pressure molding with a convex roll or convex press and then with a roll or press having a smooth surface as a second stage press. It can also be produced by pressure molding with a single-stage press of only a convex roll or a convex press plate. The convex shape of the convex roll and the convex press plate may be a semi-dome shape, a columnar shape, an elliptical columnar shape, a polygonal columnar shape, a conical shape, an elliptical cone shape, a polygonal pyramid shape, etc., a linear shape, a lattice shape, etc. An uneven embossing roll, a press plate, a special pattern uneven gravure roll formed on the surface, and a press plate may be used. Next, the negative electrode mixture layer is produced on the negative electrode current collector by drying the organic solvent of the negative electrode slurry.

  As described above, the surface unevenness of the negative electrode mixture layer, the density of the mixture layer, and the orientation of the active material can be arbitrarily adjusted with only one press twice. As an effect, by forming a layer having a long axis / short axis of the negative electrode active material particles and a layer having a long axis / low short axis of the negative electrode active material particles in the negative electrode mixture layer, The higher layer can improve the adhesion to the negative electrode current collector, relieve the stress of the negative electrode mixture layer by anchoring, and suppress the crack extension by this effect. In addition, since the negative electrode mixture layer can have a layer having a large major axis / minor axis of the negative electrode active material particle and a layer having a long major axis / minor axis of the negative electrode active material particle, a slight unevenness is formed on the surface of the negative electrode mixture layer. By providing irregularities, the specific surface area can be increased, Li dendrite can be suppressed, and rapid charging can be supported. In addition, the impregnation of the electrolytic solution can be improved.

<Positive electrode>
First, the positive electrode of a nonaqueous electrolyte lithium ion secondary battery will be described. A positive electrode is comprised from the positive mix layer which consists of a positive electrode active material, a electrically conductive agent, and a binder, and a positive electrode electrical power collector.

The positive electrode active material that can be used in the lithium ion secondary battery according to one embodiment of the present invention is made of an oxide containing lithium. Examples of the oxide containing lithium include an oxide having a layered structure such as LiCoO ₂ , LiNiO ₂ , LiMn _1/3 Ni _1/3 Co _1/3 O ₂ , LiMn _0.4 Ni _0.4 Co _0.2 O ₂ , Lithium-manganese composite oxides having a spinel structure such as LiMn ₂ O ₄ and Li _{1 + x} Mn _2-x O ₄ , or in these oxides, part of Mn is replaced with other elements such as Al and Mg Can be used.

  Since the positive electrode active material generally has high resistance, the electrical conductivity of the positive electrode active material is supplemented by mixing carbon powder as a conductive agent. Since the positive electrode active material and the conductive agent are both powders, a binder is mixed to bond the powders together, and at the same time, this powder layer is bonded to the positive electrode current collector as a mixture layer.

  As the conductive agent, natural graphite, artificial graphite, coke, carbon black, amorphous carbon, or the like can be used. When the average particle diameter of the conductive agent is smaller than the average particle diameter of the positive electrode active material powder, the conductive agent tends to adhere to the surface of the positive electrode active material particles, and the electrical resistance of the positive electrode is often reduced by a small amount of the conductive agent. Therefore, the material for the conductive agent may be selected according to the average particle diameter of the positive electrode active material.

  The positive electrode current collector may be any material that is difficult to dissolve in the electrolyte, and aluminum foil is frequently used.

  The positive electrode can be produced by a method in which a positive electrode slurry in which a positive electrode active material, a conductive agent, a binder, and an organic solvent are mixed is applied to a positive electrode current collector using a blade, that is, a doctor blade method. The positive electrode slurry applied to the positive electrode current collector is heated to dry the organic solvent, and pressure-molded by a roll press. The positive electrode mixture layer is produced on the positive electrode current collector by drying the organic solvent of the positive electrode slurry. In this manner, a positive electrode in which the positive electrode mixture layer and the positive electrode current collector are in close contact with each other can be produced.

<Separator>
The separator is made of a polymer material such as polyethylene, polypropylene, and tetrafluoroethylene, and is inserted between the positive electrode and the negative electrode manufactured as described above. The separator and the electrode sufficiently hold the electrolytic solution to ensure electrical insulation between the positive electrode and the negative electrode, and to allow the transfer of lithium ions between the positive electrode and the negative electrode.

<Electrolyte>
When an electrolytic solution is used as the electrolyte, the solvent of the electrolytic solution is propylene carbonate, butylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl acetate, ethyl acetate, propyl acetate, methyl formate, ethyl formate, propyl formate, γ A mixture of at least one selected from -butyrolactone, α-acetyl-γ-butyrolactone, α-methoxy-γ-butyrolactone, dioxolane, sulfolane, and ethylene sulfite can be used. Desirable electrolytes include LiPF ₆ , LiBF ₄ , LiSO ₂ CF ₃ , LiN [SO ₂ CF ₃ ] ₂ , LiN [SO ₂ CF ₂ CF ₃ ] ₂ , LiB [OCOCF ₃ ] ₄ , LiB. A lithium salt electrolyte such as [OCOCF ₂ CF ₃ ] ₄ containing about 0.5 to 2 M in volume concentration can be used.

<Battery>
The lithium ion secondary battery can be produced by inserting the produced electrode group into a battery container made of aluminum, stainless steel, or nickel plated steel, and then infiltrating the electrolytic solution into the electrode group. The shape of the battery can includes a cylindrical shape, a flat oval shape, a rectangular shape, and the like, and any shape can be selected as long as the electrode group can be accommodated.

  In the case of a coin-type battery, a positive electrode, a separator, and a negative electrode cut in a circular shape are stacked in this order, the stack is stored in a coin-shaped container, the lid is placed on top, and the entire battery is crimped. The

  In the case of a cylindrical battery, the electrode group is manufactured by winding with a separator inserted between the positive electrode and the negative electrode. Instead of separators, polymers such as polyethylene oxide (PEO), polymethacrylate (PMA), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), It is also possible to use a sheet-like solid electrolyte or gel electrolyte holding a lithium salt or a non-aqueous electrolyte. Further, when the electrodes are wound around two axes, an oval electrode group is also obtained.

  In the case of a prismatic battery, the positive electrode and the negative electrode are cut into strips, the positive electrode and the negative electrode are alternately stacked, and a polymer separator such as polyethylene, polypropylene, or tetrafluoroethylene is inserted between the electrodes, and the electrode group Is made.

  In order to improve safety, a sandwich-type ceramic separator in which a polymer separator is sandwiched between electrically insulating ceramic particle layers such as alumina, silica, titania, and zirconia may be used as the separator.

  The present invention does not depend on the structure of the electrode group described above, and any structure can be applied to the lithium ion secondary battery according to the present invention.

  FIG. 2 shows a cross section of a coin-type lithium ion secondary battery 201 according to an embodiment of the present invention. The coin-type lithium ion secondary battery 201 has a structure sealed with a positive electrode can 234, a negative electrode can 235, and a gasket 236. A positive electrode 207, a negative electrode 208, a separator 209, and an electrolytic solution are accommodated therein. The electrolytic solution is held in a space 237 inside the separator 209 and the coin-type lithium ion secondary battery 201. The positive electrode 207 includes a positive electrode mixture layer 230 and a positive electrode current collector 231. The negative electrode 208 includes a negative electrode mixture layer 232 and a negative electrode current collector 233. Below, the assembly method of the positive electrode 207, the negative electrode 208, and the coin-type lithium ion secondary battery 201 is demonstrated in order.

The positive electrode active material used in this example is Li _1.05 Mn _1.95 O ₄ having an average particle diameter of 20 μm. The conductive agent, the average particle diameter of 3 [mu] m, a specific surface area of 13m ² / g of natural graphite as an average particle size 0.04 .mu.m, and a carbon black having a specific surface area of 40 m ² / g, a weight ratio of 4 were mixed so that the 1 A thing was used. As the binder, a solution in which 8% by weight of PVDF was previously dissolved in N-methyl-2-pyrrolidone was used.

  These positive electrode active material, conductive agent, and PVDF were mixed so as to have a weight ratio of 90: 4: 6 and sufficiently kneaded to obtain a positive electrode slurry. The positive electrode slurry 230 was formed on the positive electrode current collector 231 by applying this positive electrode slurry to one surface of a positive electrode current collector 231 made of an aluminum foil having a thickness of 20 μm and drying it. The positive electrode 207 was pressed using a roll press, and the positive electrode mixture layer 230 was compressed. As a result, the internal resistance of the positive electrode mixture layer 230 decreased, and the interface contact resistance between the positive electrode mixture layer 230 and the positive electrode current collector 231 also decreased. This electrode was punched into a disk shape having a diameter of 15 mm to form a positive electrode 207.

  The negative electrode 208 was produced by the following method. As the negative electrode active material, natural graphite having an average particle size of 10 μm was used. As the binder, styrene / budacien rubber was mixed, and as the thickener, CMC and water were mixed.

  The obtained negative electrode slurry was applied to one side of a negative electrode current collector 233 made of a copper foil having a thickness of 10 μm and temporarily dried, whereby a negative electrode mixture layer 240 was obtained on the negative electrode current collector 233. The negative electrode current collector 233 on which the negative electrode mixture layer 240 was formed was pressed with a press plate having a plurality of convex portions formed on the surface. The surface shape of the press is a plurality of semi-dome-shaped dot-shaped convex portions formed on the surface of the press plate. The height of the abdomen where the convex part is not formed between the convex part on the surface of the press plate is adjusted so that the negative electrode mixture layer 240 does not touch when the negative electrode mixture layer 240 is pressed. did. This is because if the negative electrode mixture layer 240 is once attached to the abdomen, the negative electrode mixture layer 240 may be easily peeled off from the negative electrode current collector 233, resulting in a manufacturing failure. Next, after being pressed with a roller having a smooth surface, this was dried and a negative electrode 208 was produced. This electrode was punched into a disk shape having a diameter of 16 mm to form a negative electrode 208. The thickness of the mixture layer was about 80 μm.

  3 is a plan view of the negative electrode 301 (the negative electrode 208 in FIG. 2) and a cross-sectional view taken along the line AA ′. In FIG. 3, the negative electrode 301 includes a negative electrode current collector 304 and a negative electrode mixture layer 305. The negative electrode mixture layer 305 is composed of a layer 302 having a long diameter / high short diameter of the negative electrode active material particles and a layer 303 having a long diameter / low short diameter of the negative electrode active material particles, and has a negative electrode active material in the in-plane direction of the negative electrode current collector 304. The layer 302 having a large major axis / minor axis of the substance particles is formed in a dot shape.

  Here, the peak intensity ratio {I (110) / I (004)} from the carbon material obtained by X-ray diffraction of the layer 303 having a long major axis / low minor axis of the negative electrode active material particles is obtained. As a result of the X-ray diffraction measurement, it was 0.2, and it was determined that the negative electrode active material particles of the layer 303 having a long major axis / short minor axis of the negative electrode active material particles were not crushed and the basal plane orientation was suppressed. Further, the cross section of the negative electrode mixture layer 305 was observed with an SEM, and in the obtained SEM image, layers having different major axis / minor axis diameters of the negative electrode active material particles were observed, and the major axis / minor axis of the negative electrode active material particles were high. It can be seen that the layer 302 has a major axis / minor axis of about 2.4, and the layer having a lower major axis / minor axis of the negative electrode active material particle has a major axis / minor axis of about 1.8, so that there is almost no collapse. The major axis direction of the negative electrode active material particles in the layer 302 having a larger major axis / minor axis of the negative electrode active material particles was disposed substantially parallel to the negative electrode current collector 233, and the angle thereof was 130 degrees to 180 degrees.

Next, the positive electrode 207, the separator 209, and the negative electrode 208 were stacked, and the stacked body was housed in the positive electrode can 234 and the negative electrode can 235. The separator 209 is a polyethylene porous polymer sheet having a thickness of 40 μm. As the electrolytic solution, a mixed solution in which LiPF ₆ was dissolved in a mixed solution of ethylene carbonate and ethyl methyl carbonate (volume ratio 1: 2) to 1.0 mol / dm ³ was used. The electrolytic solution exists in the space 237 inside the separator 209 and the coin-type lithium ion secondary battery 201. The coin-type lithium ion secondary battery 201 was completed by compressing the battery with a caulking machine from the outside.

The coin-type lithium ion secondary battery 201 shown in this example was subjected to a charge / discharge test under the following conditions in a temperature of 45 ° C. environment. First, after charging to a voltage of 4.1 V with a constant current of 1 mA / cm ² , a constant current and constant voltage charge was performed for 3 hours at a constant voltage of 4.1 V. After charging was completed, a 1 hour rest period was provided, and the battery was discharged at a constant current of 1 mA / cm ² to a discharge end voltage of 3V. A two hour rest period was provided after the discharge was finished. A cycle test in which such charge, pause, discharge, and pause were repeated was performed. The capacity maintenance rates of the lithium ion secondary batteries were compared when 500 cycles of this cycle test passed. The capacity retention ratio is obtained by dividing the discharge capacity at the 500th cycle by the discharge capacity at the second cycle.

  In the present embodiment, the capacity maintenance rate after the elapse of 500 cycles is 90%, which is 90% or more. After the cycle test, the coin-type lithium ion secondary battery 201 was disassembled, the negative electrode was taken out and the negative electrode cross section SEM was observed, and no abnormality was observed in this example.

  In this example, a negative electrode was manufactured basically in the same manner as in Example 1. Unlike Example 1, instead of the press plate, an embossing roller having a plurality of conical line-shaped convex portions formed on the surface of the roller so as to draw a plurality of lines in the longitudinal direction of the negative electrode current collector was used. FIG. 4 is a plan view of the negative electrode 401 (negative electrode 208 of FIG. 2) and a cross-sectional view taken along line BB ′ in this example. In FIG. 4, the negative electrode 401 includes a negative electrode current collector 404 and a negative electrode mixture layer 405. The negative electrode mixture layer 405 is composed of a layer 402 having a large long diameter / short diameter of the negative electrode active material particles and a layer 403 having a long diameter / low short diameter of the negative electrode active material particles, and a layer having a large long diameter / short diameter of the negative electrode active material particles. 402 is formed in a linear shape.

  In this example, the capacity retention rate after the elapse of 500 cycles was 91%, which was 90% or more. After the cycle test, the coin-type lithium ion secondary battery 201 was disassembled, the negative electrode was taken out, and the negative electrode cross section SEM was observed. As a result, the negative electrode mixture layer 405 was not peeled off. Further, when the negative electrode cross section SEM was observed, no cracks were observed. In the first stage press, the pressure on the negative electrode mixture layer 405 is larger than that in the second stage press. Therefore, the negative electrode active material is crushed more in the layer 402 having a larger major axis / minor axis of the negative electrode active material particles. The stress acting on the negative electrode active material particle long axis / low short axis layer 403 is easily dispersed in the negative electrode active material particle long axis / short axis high layer 402 by the second-stage press with a lower pressure. This is probably because cracks hardly occur.

For the coin-type lithium ion secondary battery 201 shown in this example, a rate test was performed under the following conditions in a temperature 25 ° C. environment. First, after charging to a voltage of 4.1 V with a constant current of 1 mA / cm ² , a constant current and constant voltage charge was performed for 3 hours at a constant voltage of 4.1 V. After the charging is completed, every downtime 1 hour, until the discharge end voltage 3V, was discharged at a constant current of 0.25C (0.6mA / cm ²⁾ and 2.5C (6mA / cm ²⁾ (here 1C = 2.4 mA / cm ² , assuming 0.25 C = 0.6 mA / cm ² ). By performing such a rate test, the ratio of the discharge capacity (ratio between the discharge capacity at 2.5 C and the discharge capacity at 0.25 C; 2.5 C / 0.25 C) is calculated, and the rate characteristics of each battery are calculated. Evaluated. The higher this ratio, the better the rate characteristics, and the battery can withstand rapid charge / discharge capacity.

  When the rate characteristic in the coin-type lithium ion secondary battery 201 was examined, it was 0.85 or more in this example. When the coin-type lithium ion secondary battery 201 was disassembled and the negative electrode was visually observed, in the present example, the surface of the negative electrode had a carbon color and no abnormality was observed. In this example, since the negative electrode mixture layer 405 includes a layer 402 having a large major axis / minor axis of the negative electrode active material particle and a layer 403 having a long major axis / minor axis of the negative electrode active material particle, the surface of the negative electrode mixture layer 405 is slightly It is considered that unevenness was formed on the surface, and by providing the unevenness, the specific surface area was increased and lithium dendrite precipitation could be suppressed. Thereby, in a present Example, it becomes possible to respond to quick charge.

  In this example, a negative electrode was manufactured basically in the same manner as in Example 1. Unlike Example 1, a gravure roll with a special concavity and convexity having a conical convex portion formed on the surface was used as a press so that a layer having a large major axis / minor minor axis of the negative electrode active material particles could be formed in a lattice shape. FIG. 5 is a plan view of the negative electrode 501 (the negative electrode 208 of FIG. 2) and a cross-sectional view taken along the line CC ′ in this example. In FIG. 5, the negative electrode 501 includes a negative electrode current collector 504 and a negative electrode mixture layer 505. The negative electrode mixture layer 505 is composed of a layer 502 having a long diameter / short diameter high of the negative electrode active material particles and a layer 503 having a long diameter / low short diameter of the negative electrode active material particles. 502 is formed in a lattice shape.

  In this example, the capacity retention rate after the elapse of 500 cycles was 92%, which was 90% or more. In this example, since the area of the concave portion formed in the portion corresponding to the layer 502 having a longer major axis / minor minor axis of the negative electrode active material particle 505 of the negative electrode mixture layer 505 is larger, the impregnation property of the electrolytic solution is further improved. It is thought. After the cycle test, the coin-type lithium ion secondary battery 201 was disassembled, the negative electrode was taken out and the negative electrode cross section SEM was observed. As a result, the negative electrode mixture layer 505 was not peeled off. Further, when the negative electrode cross section SEM was observed, no cracks were observed.

  When the rate characteristic in the coin-type lithium ion secondary battery 201 was examined in the same manner as in Example 2, it was 0.85 or more. When the coin-type lithium ion secondary battery 201 was disassembled and the negative electrode was visually observed, in the present example, the surface of the negative electrode had a carbon color and no abnormality was observed.

  In the embodiment described above, a coin-type lithium ion secondary battery is exemplified. The shape of these batteries, electrode specifications, and the like can be arbitrarily changed within the scope of the gist of the present invention, and the present invention is not limited to these examples.

[Comparative Example 1]
In this comparative example, the negative electrode 208 was manufactured basically in the same manner as in Example 1. The difference from Example 1 is that a press roller having a plurality of convex portions formed on the surface is pressed only by a press roller having a smooth surface without using a press. When observed with an SEM, in this comparative example, there was no distinction between a layer with a long / short diameter of the active material of the negative electrode mixture layer and a layer with a low length, and the particles were almost crushed and arranged in parallel with the current collector. Further, as a result of X-ray diffraction using a disk having a diameter of 16 mm punched from the negative electrode, the peak intensity ratio {I (110) / I (004)} from the carbon material was 0.08. Thus, when only the press roller having a smooth surface is pressed, if the active material particles of the negative electrode mixture layer are crushed, the peak intensity ratio {I (110) / I (004)} from the carbon material may be lowered. Recognize.

  In this comparative example, the capacity retention rate after the elapse of 500 cycles was 79%, and the capacity retention rate was considerably lowered. After the cycle test, the coin-type lithium ion secondary battery 201 was disassembled, the negative electrode was taken out and the negative electrode cross section SEM was observed. In this comparative example, many cracks were observed in the negative electrode mixture layer. This is presumably because the isolated graphite group no longer forms a conductive path with the negative electrode current collector due to cracks, and the capacity is reduced accordingly.

  When rate characteristics were evaluated in the same manner as in Example 2, it was 0.7. When the coin-type lithium ion secondary battery 201 was disassembled and the negative electrode 208 was visually observed, the entire surface of the negative electrode was grayish white in this comparative example, and as a result of further elemental analysis, Li dendrite was deposited. Turned out. In this comparative example, since the surface of the negative electrode mixture layer is almost smooth by pressing with a uniform surface pressure, Li dendrite is liable to precipitate and is not suitable for rapid charging from the viewpoint of safety.

  FIG. 6 schematically shows the internal structure of the nonaqueous electrolyte secondary battery. The non-aqueous electrolyte secondary battery is a general term for electrochemical devices that can store and use electrical energy by occluding and releasing ions to and from electrodes in the non-aqueous electrolyte. In this example, a lithium ion secondary battery will be described as a representative example.

  In the lithium ion secondary battery 601 of FIG. 6, an electrode group including a positive electrode 607, a negative electrode 608, and a separator 609 inserted between both electrodes is housed in a battery container 602 in a sealed state. A lid 603 is provided on the top of the battery container 602, and the lid 603 has a positive electrode external terminal 604, a negative electrode external terminal 605, and a liquid injection port 606. After the electrode group was stored in the battery container 602, the lid 603 was put on the battery container 602, and the outer periphery of the lid 603 was welded to be integrated with the battery container 602. For attachment of the lid 603 to the battery container 602, other methods such as caulking and adhesion can be adopted in addition to welding.

  The upper part of the laminate is electrically connected to the positive external terminal 604 and the negative external terminal 605 via the positive lead 610 and the negative lead 611. The positive electrode 607 is connected to the positive external terminal 604 via the positive lead 610. The negative electrode 608 is connected to the negative external terminal 605 via a negative lead wire 611. Note that the positive electrode lead wire 610 and the negative electrode lead wire 611 can take any shape such as a wire shape or a plate shape. The positive electrode lead wire 610 and the negative electrode lead wire 611 may have any shape and material as long as the material can reduce ohmic loss when a current is passed and the material does not react with the electrolytic solution.

  Further, an insulating sealing material 612 is inserted between the positive electrode external terminal 604 or the negative electrode external terminal 605 and the battery container 602 so that both terminals are not short-circuited via the lid 603. The insulating sealing material 612 can be selected from a fluororesin, a thermosetting resin, a glass hermetic seal, and the like, and any material that does not react with the electrolyte and has excellent airtightness can be used.

In this example, the positive electrode active material LiNi _1/3 Mn _1/3 Co _1/3 O ₂ having an average particle diameter of 10 μm, a positive electrode manufactured using carbon black as a conductive agent and polyvinylidene fluoride (PVDF) as a binder. The following tests were conducted using 607. The weight composition of the positive electrode active material, the conductive agent, and the binder was 88: 7: 5. The electrode area to which the positive electrode slurry was applied was 10 cm × 10 cm, and the mixture layer thickness was 100 μm.

  The negative electrode 608 was manufactured as shown in Example 2. The electrode area was 10 cm × 10 cm, and the negative electrode mixture layer thickness was about 80 μm.

As the electrolytic solution, a mixed solution in which LiPF ₆ was dissolved in a mixed solution of ethylene carbonate and ethyl methyl carbonate (volume ratio 1: 2) to 1.0 mol / dm ³ was used. A plurality of prismatic batteries shown in FIG. 6 were manufactured.

  Next, FIG. 7 shows a nonaqueous electrolyte secondary battery system 700 of the present invention in which two lithium ion secondary batteries 701a and 701b manufactured as shown in FIG. 6 are connected in series. The number of batteries can be arbitrarily changed in series and in parallel according to the voltage and capacity required by the system.

  Each of the lithium ion secondary batteries 701a and 701b has a structure in which an electrode group having the same specifications including a positive electrode 707, a negative electrode 708, and a separator 709 is inserted into a battery container 702. A positive electrode external terminal 704 and an external negative electrode are formed on the upper surface of a lid 703. A terminal 705 is provided. An insulating sealing material 712 is inserted between the positive electrode external terminal 704 and the lid 703 of the negative electrode external terminal 705 so that the external terminals are not short-circuited via the cover 703. Although one positive electrode 707 and one negative electrode 708 in the figure are shown one by one, actually, 20 positive electrodes 707 and negative electrodes 708 are alternately stacked via separators 709. The number of electrodes is such that an insulating sealing material 712 is inserted between each external terminal and the battery container 702 so that the external terminals are not short-circuited. In the figure, components corresponding to the positive electrode lead wire 610 and the negative electrode lead wire 611 in FIG. 6 are omitted, but the internal structure of the lithium ion secondary batteries 701a and 701b is the same as that in FIG. A liquid injection port 706 was provided on the top of the lid 703.

  A negative external terminal 705 of the lithium ion secondary battery 701 a is connected to a negative input terminal of the charge / discharge controller 716 by a power cable 713. The positive external terminal 704 of the lithium ion secondary battery 701a is connected to the negative external terminal 705 of the lithium ion secondary battery 701b via the power cable 714. A positive external terminal 704 of the lithium ion secondary battery 701 b is connected to a positive input terminal of the charge / discharge controller 716 by a power cable 715. With such a wiring configuration, the two lithium ion secondary batteries 701a and 701b can be charged or discharged.

  The charge / discharge controller 716 transmits and receives power to and from an externally installed device (hereinafter referred to as an external device) 719 via power cables 717 and 718. The external device 719 includes various electric devices such as an external power source and a regenerative motor for supplying power to the charge / discharge controller 716, and an inverter, a converter, and a load that supply power from the system. An inverter or the like may be provided depending on the type of AC and DC that the external device supports. As these devices, known devices can be arbitrarily applied.

  In addition, a power generation device 722 simulating the operating conditions of a wind power generator was installed as a device that generates renewable energy, and was connected to the charge / discharge controller 716 via power cables 720 and 721. When the power generation device 722 generates power, the charge / discharge controller 716 shifts to the charge mode, supplies power to the external device 719, and charges surplus power to the lithium ion secondary batteries 701a and 701b. Further, when the power generation amount simulating the wind power generator is smaller than the required power of the external device 719, the charge / discharge controller 716 operates to discharge the lithium ion secondary batteries 701a and 701b. The power generation device 722 can be replaced with another power generation device, that is, any device such as a solar cell, a geothermal power generation device, a fuel cell, or a gas turbine generator. The charge / discharge controller 716 stores a program capable of automatic operation so as to perform the above-described operation.

  The lithium ion secondary batteries 701a and 701b are normally charged to obtain a rated capacity. For example, constant voltage charging of 4.1V or 4.2V can be performed for 0.5 hour at a charging current of 1 hour rate. The charging conditions are determined by the design of the material type, amount of use, etc. of the lithium ion secondary battery. Therefore, the charging conditions are optimal for each battery specification.

  After charging the lithium ion secondary batteries 701a and 701b, the charge / discharge controller 716 is switched to the discharge mode to discharge each battery. Normally, the discharge is stopped when a certain lower limit voltage is reached.

  The system described above is designated as S1, and the external device 719 supplies power during charging and consumes power during discharging. In this example, up to 5 hour rate discharge was carried out, and a high capacity of 90% was obtained with respect to the capacity during 1 hour rate discharge. The capacity drop when performing 500 charge / discharge cycles was not substantially observed, and the capacity under the above conditions was maintained at 90%. In addition, the power generation device 622 simulating a wind power generator could be charged at a rate of 3 hours during power generation.

  In addition, you may change a specific structural material, components, etc. in the range which does not change the summary of this invention. In addition, if the constituent elements of the present invention are included, a known technique can be added or replaced by a known technique, and the power generator can be arbitrarily regenerated such as sunlight, geothermal heat, wave energy, etc. It can be replaced with an energy generation system.

[Comparative Example 2]
With the composition of the negative electrode of Comparative Example 1, a negative electrode was manufactured, and a plurality of lithium ion secondary batteries shown in FIG. 6 were manufactured. According to this comparative example, only one stage was pressed with a roller having a smooth surface in the pressing process, and the system of FIG. 7 was manufactured under the same conditions as in Example 4.

  Using this system, the external device 719 supplies power during charging and consumes power during discharging. In this example, the discharge was carried out up to a 5-hour rate discharge, and a high capacity of 90% was obtained at the initial 10 cycles with respect to the capacity during the 1-hour rate discharge. However, compared with Example 4, the capacity decreased by 18%.

  When the battery was disassembled after the test and the negative electrode was visually observed, many portions where the mixture layer dropped from the current collector were observed. Since the peak intensity ratio {I (110) / I (004)} from the carbon material obtained by X-ray diffraction of the negative electrode mixture layer was less than 0.1, all the basal surfaces were parallel to the negative electrode current collector. Since the negative electrode mixture layer was pressed once at the same surface pressure, it was considered that stress remained in the negative electrode mixture layer, and it was easy to promote crack extension due to the volume change of the negative electrode active material due to the charge / discharge cycle. For this reason, it can be explained that the negative electrode mixture layer easily falls off from the negative electrode current collector.

  The application of the nonaqueous electrolyte secondary battery according to the present invention is not particularly limited. For example, it can be used as a power source for portable information communication devices such as a personal computer, a word processor, a cordless telephone cordless handset, an electronic book player, a cellular phone, a car phone, a handy terminal, a transceiver, and a portable wireless device. Also, as a power source for various portable devices such as portable copiers, electronic notebooks, calculators, LCD TVs, radios, tape recorders, headphone stereos, portable CD players, video movies, electric shavers, electronic translators, voice input devices, memory cards, etc. Can be used. In addition, it can be used as household electric appliances such as refrigerators, air conditioners, TVs, stereos, water heaters, oven microwaves, dishwashers, dryers, washing machines, lighting fixtures, toys and the like. In addition, it can be used as a battery for electric tools and nursing equipment (electric wheelchairs, electric beds, electric bathing facilities, etc.) regardless of whether they are for home use or business use. Furthermore, as industrial applications, as power sources for medical equipment, construction machinery, power storage systems, elevators, unmanned mobile vehicles, and mobiles such as electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, golf carts, turret vehicles, etc. The present invention can be applied as a power source. Furthermore, it is also possible to charge the battery module of the present invention with electric power generated from a solar cell or a fuel cell and use it as a power storage system that can be used outside the ground, such as a space station, spacecraft, or space base.

101, 208, 301, 401, 501, 608, 708 Negative electrode 102, 302, 402, 502 Negative active material particle major axis / minor axis higher layer 103, 303, 403, 503 Negative electrode active material particle major axis / minor axis Lower layer 104, 233, 304, 404, 504 Negative electrode current collector 105, 305, 405, 505 Negative electrode mixture layer 201 Coin type lithium ion secondary battery 207, 607, 707 Positive electrode 209, 609, 709 Separator 230 Positive electrode mixture Layer 231 Positive electrode current collector 234 Positive electrode can 235 Negative electrode can 236 Gasket 237 Space 601, 701 a, 701 b Lithium ion secondary battery 602, 702 Battery container 603, 703 Lid 604, 704 Positive electrode external terminal 605, 705 Negative electrode external terminal 606, 706 Injection port 610 Positive electrode lead wire 611 Negative electrode lead wire 612 Edge seal material 700 a non-aqueous electrolyte secondary battery system 712 insulating sealing material 713,714,715,717,718,720,721 power cable 716 charge and discharge controller 719 external devices 722 power generator

Claims (10)

A negative electrode for a nonaqueous electrolyte secondary battery having a negative electrode mixture layer formed on a negative electrode current collector,
The negative electrode mixture layer includes negative electrode active material particles,
The negative electrode active material particles are made of a carbon material,
The negative electrode mixture layer has a layer having a long diameter / short diameter high of the negative electrode active material particles and a layer having a low long diameter / short diameter of the negative electrode active material particles,
The major axis / minor axis of the negative electrode active material particles contained in the layer having a larger major axis / minor axis of the negative electrode active material particles is the major axis of the negative electrode active material particles contained in the layer having the major axis / lower minor axis of the negative electrode active material particles / Larger than the minor axis,
In the in-plane direction of the negative electrode current collector, a layer having a low major axis / minor axis of the negative electrode active material particles is formed between layers having a large major axis / minor axis of the negative electrode active material particles,
A negative electrode for a non-aqueous electrolyte secondary battery in which the direction of the major axis of the negative electrode active material particles contained in the layer having a larger major axis / minor axis of the negative electrode active material particles is arranged in parallel to the negative electrode current collector. In claim 1,
Unevenness is formed on the surface of the negative electrode mixture layer,
A layer having a higher major axis / minor axis of the negative electrode active material particles is formed in the concave portion of the negative electrode mixture layer,
A negative electrode for a non-aqueous electrolyte secondary battery, wherein a layer having a lower major axis / minor axis of the negative electrode active material particles is formed on the convex portion of the negative electrode mixture layer. In claim 1 or 2,
The peak intensity ratio {I (110) / I (004)} from the carbon material obtained by X-ray diffraction of the layer having a long axis / low axis of the negative electrode active material particles is 0.1 or more and 0.5 or less. Negative electrode for non-aqueous electrolyte secondary battery. In any one of Claims 1 thru | or 3,
In the in-plane direction of the negative electrode current collector, the negative electrode active material particle has a high major axis / minor axis layer formed in a dot shape, a linear shape, or a lattice shape, as a negative electrode for a non-aqueous electrolyte secondary battery. In any one of Claims 1 thru | or 4,
The negative electrode for a non-aqueous electrolyte secondary battery has the same composition of the layer having a large major axis / minor axis of the negative electrode active material particle and the layer having a small major axis / minor axis of the negative electrode active material particle. In any one of Claims 1 thru | or 5,
A negative electrode for a non-aqueous electrolyte secondary battery, wherein the negative electrode mixture layer contains a thickener.   A nonaqueous electrolyte secondary battery using the negative electrode for a nonaqueous electrolyte secondary battery according to claim 6.   A nonaqueous electrolyte secondary battery system using a plurality of the nonaqueous electrolyte secondary batteries of claim 7. A method for producing a negative electrode for a non-aqueous electrolyte secondary battery having a negative electrode mixture layer formed on a negative electrode current collector,
The negative electrode mixture layer includes negative electrode active material particles,
The negative electrode active material particles include a carbon material,
The negative electrode mixture layer has a layer having a long diameter / short diameter high of the negative electrode active material particles and a layer having a low long diameter / short diameter of the negative electrode active material particles,
The major axis / minor axis of the negative electrode active material particles contained in the layer having a larger major axis / minor axis of the negative electrode active material particles is the major axis of the negative electrode active material particles contained in the layer having the major axis / lower minor axis of the negative electrode active material particles / Larger than the minor axis,
In the in-plane direction of the negative electrode current collector, a layer having a low major axis / minor axis of the negative electrode active material particles is formed between layers having a large major axis / minor axis of the negative electrode active material particles,
A step of pressing the negative electrode mixture layer with a press roller formed with a plurality of convex portions to form a layer having a higher major axis / minor axis of the negative electrode active material particles;
The negative electrode mixture layer is pressed with a press roller having a smooth surface, and the direction of the major axis of the negative electrode active material particles contained in the layer having a larger major axis / minor axis of the negative electrode active material particles is parallel to the negative electrode current collector. A process for producing a negative electrode for a non-aqueous electrolyte secondary battery. In claim 9,
By pressing the negative electrode mixture layer with a press roller having a smooth surface, a peak intensity ratio {I (110 ) / I (004)} is 0.1 or more and 0.5 or less, and the manufacturing method of the negative electrode for nonaqueous electrolyte secondary batteries.