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WO2015068351A1 - Substance active d'électrode négative et dispositif de stockage d'électricité - Google Patents

Substance active d'électrode négative et dispositif de stockage d'électricité Download PDF

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Publication number
WO2015068351A1
WO2015068351A1 PCT/JP2014/005424 JP2014005424W WO2015068351A1 WO 2015068351 A1 WO2015068351 A1 WO 2015068351A1 JP 2014005424 W JP2014005424 W JP 2014005424W WO 2015068351 A1 WO2015068351 A1 WO 2015068351A1
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Prior art keywords
negative electrode
active material
electrode active
silicon
secondary battery
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English (en)
Japanese (ja)
Inventor
加代子 湯川
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Toyota Industries Corp
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Toyota Industries Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
    • C08G77/60—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule in which all the silicon atoms are connected by linkages other than oxygen atoms
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention can be used in various fields such as semiconductors, electricity and electrons, and a negative electrode active material useful for non-aqueous secondary batteries such as lithium ion secondary batteries, and a storage device using the negative electrode active material for the negative electrode It is about
  • the lithium ion secondary battery is a secondary battery that has a high charge / discharge capacity and can achieve high output. Currently, it is mainly used as a power source for portable electronic devices, and is further expected as a power source for large-sized electric devices for electric vehicles and homes expected to be widely used in the future.
  • a lithium ion secondary battery has an active material capable of inserting and removing lithium (Li) on a positive electrode and a negative electrode, respectively. Then, it operates by moving lithium ions in the electrolytic solution provided between both electrodes.
  • lithium-containing metal complex oxides such as lithium cobalt complex oxide are mainly used as the active material of the positive electrode, and carbon materials having a multilayer structure are mainly used as the active material of the negative electrode There is.
  • the performance of the lithium ion secondary battery depends on the materials of the positive electrode, the negative electrode and the electrolyte that constitute the secondary battery. Above all, research and development of active material materials that form active materials are actively conducted. For example, silicon or silicon oxide having a higher capacity than carbon is being studied as a negative electrode active material.
  • silicon As the negative electrode active material, a battery with higher capacity than using a carbon material can be obtained.
  • silicon has a large volume change associated with absorption and release of Li during charge and discharge. Therefore, there is a problem that silicon is pulverized and is separated or separated from the current collector, and the charge and discharge cycle life of the battery is short. Therefore, by using silicon oxide as the negative electrode active material, it is possible to suppress the volume change associated with the storage and release of Li during charge and discharge than silicon.
  • SiO x silicon oxide
  • SiO x decomposes into Si and SiO 2 when heat-treated. This is called disproportionation reaction, and it is separated into two phases of Si phase and SiO 2 phase by internal reaction of solid.
  • the Si phase obtained by separation is very fine.
  • the SiO 2 phase covering the Si phase has the function of suppressing the decomposition of the electrolytic solution. Therefore, a secondary battery using a negative electrode active material composed of SiO x decomposed into Si and SiO 2 is excellent in cycle characteristics.
  • Patent Document 1 describes a method of heating and subliming metal silicon and SiO 2 into silicon oxide gas and cooling it to produce SiO x . According to this method, the particle size of silicon particles constituting the Si phase can be made into nanosize of 1 nm-5 nm.
  • JP-A 2009-102219 decomposes a silicon raw material into an elemental state in high temperature plasma, and rapidly cools it to liquid nitrogen temperature to obtain silicon nanoparticles, and then this silicon nanoparticles are A manufacturing method of fixing in a SiO 2 -TiO 2 matrix by a sol-gel method or the like is described.
  • the matrix is limited to a sublimable material.
  • the manufacturing method described in Patent Document 2 requires high energy for plasma discharge.
  • the silicon composite obtained by these manufacturing methods there is a problem that the dispersibility of silicon particles in the Si phase is low and aggregation is easy.
  • the secondary battery using it as a negative electrode active material has a low initial capacity, and the cycle characteristics also deteriorate.
  • an oxide layer is required to fix nanosilicon in manufacturing, causing an irreversible reaction between the oxide layer and Li, thereby reducing the capacity of the cell. There is a defect that causes it.
  • Non-patent Document 1 describes a method of synthesizing layered polysilane by reacting hydrogen chloride (HCl) and calcium disilicide (CaSi 2 ).
  • HCl hydrogen chloride
  • CaSi 2 calcium disilicide
  • the layered polysilane described in Non-Patent Document 1 has a large specific surface area and contains a large amount of SiO 2 component
  • the layered polysilane described in Non-Patent Document 1 is a negative electrode active material material of a secondary battery
  • decomposition of the electrolyte is promoted if the specific surface area of the negative electrode active material is large, so that the irreversible capacity consumed by the negative electrode in the lithium ion secondary battery becomes large, lithium It is difficult to increase the capacity of the ion secondary battery.
  • the present inventors conducted intensive studies on the layered polysilane described in Non-Patent Document 1, and heat treating this layered polysilane at a temperature of over 100 ° C. in a non-oxidizing atmosphere to obtain nano-sized specific surface area. It has been found that silicon can be obtained.
  • the layered polysilane described in Non-Patent Document 1 is represented by a composition formula (SiH) n , and has a basic skeleton having a structure in which a plurality of six-membered rings composed of silicon atoms are connected.
  • the Raman spectrum of this layered polysilane is shown in FIG. 1, and the Raman spectrum of single crystal silicon is shown in FIG.
  • the peak of the Si—Si bond observed at 520 cm ⁇ 1 in single crystal silicon (FIG. 2) is shifted to around 320 cm ⁇ 1 in the lower frequency side of layered polysilane (FIG. 1) compared to single crystal silicon. That is, it is thought that the Si—Si bond is weakened by the layered polysilane structure, and nanosiliconization under mild conditions becomes possible.
  • the present invention has been made in view of such circumstances, and an object of the present invention is to provide a negative electrode active material made of nanosilicon exhibiting a high capacity retention rate.
  • the content of the crystalline silicon is 40% or less of the total silicon. More preferably, the crystalline silicon content is 33% or less of the total silicon.
  • the negative electrode active material of the present invention is composed of nanosilicon in which the content of crystalline silicon is 40% or less of the total silicon.
  • FIG. 1 is an X-ray diffraction spectrum of the nanosilicon powder obtained in Example 1.
  • 2 shows an SEM image of a nanosilicon material according to Example 1.
  • 1 shows an enlarged SEM image of a nanosilicon material according to Example 1.
  • FIG. 7 is an X-ray diffraction spectrum of nanosilicon powder according to Comparative Example 1;
  • the negative electrode active material of the present invention has a structure in which a plurality of plate-like silicon bodies in which flat nano-silicon particles are arranged in layers are stacked in the thickness direction. This structure is confirmed by SEM observation as shown in FIG. 5 and FIG. In addition, what expanded the rectangular part shown in FIG. 5 is shown by FIG. It is observed that the plate-like silicon body has a thickness of about 10 nm to about 100 nm. The thickness of the plate-like silicon body is preferably in the range of 20 nm to 90 nm from the viewpoint of strength and ease of insertion and detachment of lithium ions and the like. The length of the plate-like silicon body in the long axis direction was 0.1 ⁇ m to 50 ⁇ m.
  • the negative electrode active material can be manufactured by heat-treating a layered polysilane represented by a composition formula (SiH) n in a non-oxidizing atmosphere without forming a structure in which a plurality of six-membered rings composed of silicon atoms are linked.
  • This layered polysilane can be obtained by reacting calcium disilicide (CaSi 2 ) with an acid.
  • CaSi 2 calcium disilicide
  • it can be produced by reacting hydrogen chloride (HCl) and calcium disilicide (CaSi 2 ).
  • Calcium disilicide (CaSi 2 ) forms a layered crystal in which a Ca atomic layer is inserted between the (111) faces of diamond-shaped Si, and layered polysilane by extracting calcium (Ca) in reaction with an acid. Is obtained.
  • a mixture of hydrogen fluoride (HF) and hydrogen chloride (HCl) can also be used as the acid for extracting Ca.
  • impurities such as CaF 2 and CaSiO-based are generated. It is not preferable that the amount of hydrogen fluoride (HF) be higher than this ratio, because it is difficult to separate this impurity from the layered polysilane.
  • the reaction is preferably carried out under an inert gas atmosphere.
  • the reaction time and reaction temperature are not particularly limited, but the reaction temperature is usually 0 ° C. to 100 ° C., and the reaction time is 0.25 to 24 hours.
  • the reaction produces CaCl 2 and the like, which can be removed by washing with water.
  • a nanosilicon material is obtained by heat-processing the layered polysilane obtained by the said manufacturing method in non-oxidizing atmosphere.
  • Heating methods in heat treatment are roughly classified into combustion heating by fossil fuel and electric heating by electricity. Electric heating is advantageous in that temperature control is easy compared to combustion heating and that high temperature can be easily obtained. As a heating method in heat treatment, electric heating is widely used.
  • Electric heating includes resistance heating, induction heating, microwave heating, dielectric heating, far infrared heating, arc heating, electron beam heating, plasma heating and the like.
  • resistance heating is simple and easy to use in principle, and the heating efficiency is high, so it is easy to enlarge the scale of heat treatment.
  • resistive heating has the advantage of low initial and running costs. Therefore, heat treatment by resistance heating is preferably used as electric heating.
  • induction heating or microwave heating although initial heating is possible although high-speed heating is possible, it may be difficult to enlarge the heat treatment scale.
  • an inert gas atmosphere and a vacuum atmosphere are exemplified.
  • the inert gas is not particularly defined unless it contains oxygen such as argon, helium or nitrogen.
  • the heat treatment temperature is preferably in the range of 300 ° C. to 1000 ° C., particularly preferably in the range of 500 ° C. to 900 ° C.
  • the removal treatment for reducing the content of crystalline silicon include a decantation method, a centrifugal separation method, a chemical treatment method such as alkali treatment, and a magnetic separation method. These removal treatments can be carried out in the form of calcium disilicide or in the form of layered polysilane. Furthermore, these removal processes can also be performed on the nanosilicon material after heat treatment of the layered polysilane.
  • an aqueous solvent can be used as a dispersion medium.
  • washing may be performed using a sodium hydroxide aqueous solution or the like.
  • chemical treatment method oxidation of the silicon component proceeds and the oxygen content may increase, so it is preferable to use the decantation method or the centrifugal separation method as the removal treatment for reducing the content of crystalline silicon. .
  • the content of crystalline silicon is preferably 40% or less of the total silicon, and more preferably 33% or less of the total silicon.
  • the amount of oxygen contained is preferably 30% by mass or less, more preferably 15% by mass or less, and 10% by mass of oxygen It is particularly desirable that
  • the negative electrode has a current collector and a negative electrode active material layer bound to the surface of the current collector.
  • the current collector refers to a chemically inactive electron conductor for keeping current flowing to the electrode during discharge or charge of the power storage device.
  • the current collector at least one selected from silver, copper, gold, tungsten, cobalt, zinc, nickel, iron, platinum, tin, indium, titanium, ruthenium, tantalum, chromium, molybdenum, and metal materials such as stainless steel Can be illustrated.
  • the current collector may be coated with a known protective layer. What processed the surface of a collector by a well-known method may be used as a collector.
  • the current collector can take the form of a foil, a sheet, a film, a line, a rod, a mesh or the like. Therefore, metal foils, such as copper foil, nickel foil, and stainless steel foil, can be suitably used as the current collector, for example.
  • the thickness is preferably in the range of 1 ⁇ m to 100 ⁇ m.
  • the negative electrode active material layer contains a negative electrode active material.
  • the negative electrode active material layer further generally contains a binder.
  • the negative electrode active material layer may further contain a conductive aid, if necessary.
  • the negative electrode active material contains the above-mentioned negative electrode active material of the present invention.
  • another negative electrode active material may be included.
  • a material capable of inserting and extracting lithium ions can be used as another negative electrode active material.
  • the material capable of absorbing and desorbing lithium ions is not particularly limited as long as it is a single body, an alloy or a compound capable of absorbing and desorbing lithium ions.
  • negative electrode active materials Li, Group 14 elements such as carbon, germanium and tin, Group 13 elements such as aluminum and indium, Group 12 elements such as zinc and cadmium, Group 15 elements such as antimony and bismuth, magnesium and calcium And other Group 11 elements such as alkaline earth metals, silver, and gold may be used alone. It is also preferable to use, as the negative electrode active material, an alloy or a compound in which another element such as a transition metal is combined with a simple substance such as tin. Specific examples of the alloy or the compound include tin-based materials such as Ag—Sn alloys, Cu—Sn alloys, Co—Sn alloys, and carbon-based materials such as various graphites.
  • fluorine-containing resins such as polyvinylidene fluoride, polytetrafluoroethylene and fluororubber, thermoplastic resins such as polypropylene and polyethylene, imide resins such as polyimide and polyamideimide, alkoxysilyl group-containing resin, polyacrylic acid PAA), polymers having a hydrophilic group such as carboxymethyl cellulose (CMC), and the like can be exemplified.
  • the conductive support agent optionally contained in the negative electrode active material layer is added to enhance the conductivity of the electrode. Therefore, the conductive additive may be optionally added when the conductivity of the electrode is insufficient, and may not be added when the conductivity of the electrode is sufficiently excellent.
  • the conductive support agent may be any chemically active high electron conductor, and carbon black particles such as carbon black, graphite, acetylene black, ketjen black (registered trademark), vapor grown carbon fiber (vapor grown) Carbon Fiber (VGCF) is illustrated. These conductive assistants can be added to the negative electrode active material layer singly or in combination of two or more.
  • the blending ratio of the conductive auxiliary in the negative electrode active material layer is not particularly limited, it is preferable that the mass ratio of the negative electrode active material: conductive auxiliary is 1: 0.01 to 1: 0.5. If the amount of the conductive additive is too small, efficient conductive paths may not be formed. If the amount of the conductive additive is too large, the formability of the negative electrode active material layer may be deteriorated and the energy density of the electrode may be reduced. .
  • the negative electrode of the power storage device includes a negative electrode active material powder, a conductive auxiliary such as carbon powder, a binder, and an appropriate amount of a solvent and mixed to form a slurry, which is a roll coating method, a dip coating method, a doctor blade method, It can be produced by applying on a current collector by a method such as spray coating method or curtain coating method, and drying or curing the binder.
  • the solvent include organic solvents such as N-methyl-2-pyrrolidone, methanol and methyl isobutyl ketone, and water.
  • the dried negative electrode may be compressed to increase the electrode density.
  • organic solvent there is no particular limitation on the organic solvent, and the organic solvent may be a mixture of plural solvents.
  • Organic solvents such as N-methyl-2-pyrrolidone and N-methyl-2-pyrrolidone and ester solvents (ethyl acetate, n-butyl acetate, butyl cellosolve acetate, butyl carbitol acetate etc.) or glyme solvents (diglyme, triglyme, Particularly preferred are mixed solvents of tetraglyme and the like.
  • the negative electrode When the power storage device having the above-described negative electrode is a lithium ion secondary battery, the negative electrode may be pre-doped with lithium.
  • the negative electrode In order to dope the negative electrode with lithium, for example, an electrode forming method in which a half cell is assembled using metallic lithium as a counter electrode and electrochemically dope lithium can be used.
  • the doping amount of lithium is not particularly limited.
  • the positive electrode may be any one that can be used in non-aqueous secondary batteries.
  • the positive electrode has a current collector and a positive electrode active material layer bound on the current collector.
  • the positive electrode active material layer contains a positive electrode active material and a binder, and may further contain a conductive aid.
  • the positive electrode active material, the conductive additive and the binder are not particularly limited as long as they can be used in a lithium ion secondary battery.
  • the positive electrode has a positive electrode active material capable of inserting and extracting lithium ions.
  • the positive electrode has a current collector and a positive electrode active material layer bonded to the surface of the current collector.
  • the positive electrode active material layer contains a positive electrode active material, and optionally, a binder and / or a conductive aid.
  • the collector of the positive electrode is not particularly limited as long as it is a metal that can withstand a voltage suitable for the active material to be used.
  • a collector of the positive electrode for example, at least one selected from silver, copper, gold, aluminum, tungsten, cobalt, zinc, nickel, iron, platinum, tin, indium, titanium, ruthenium, tantalum, chromium, molybdenum, and stainless steel Metal materials, such as steel, can be illustrated.
  • the current collector may be coated with a known protective layer. What processed the surface of a collector by a well-known method may be used as a collector.
  • the current collector can take the form of a foil, a sheet, a film, a line, a rod, a mesh or the like. Therefore, as the current collector, for example, metal foils such as copper foil, nickel foil, aluminum foil, and stainless steel foil can be suitably used.
  • the thickness is preferably in the range of 1 ⁇ m to 100 ⁇ m.
  • the binder and the conductive additive of the positive electrode are the same as those described for the negative electrode.
  • At least one element selected from Li, Fe, Cr, Cu, Zn, Ca, Mg, S, Si, Na, K, Al, Zr, Ti, P, Ga, Ge, V, Mo, Nb, W, La 1.7 ⁇ f ⁇ 2.1), Li 2 MnO 3 can be mentioned.
  • a positive electrode active material a solid solution composed of spinel such as LiMn 2 O 4 , Li 2 Mn 2 O 4 and the like, and a mixture of spinel and layered compound, LiMPO 4 , LiMVO 4 or Li 2 MSiO 4 (M in the formula And polyanionic compounds such as those selected from at least one of Co, Ni, Mn, and Fe).
  • tavorite compound (the M a transition metal) LiMPO 4 F such as LiFePO 4 F represented by, Limbo 3 such LiFeBO 3 (M is a transition metal
  • LiMPO 4 F such as LiFePO 4 F represented by, Limbo 3 such LiFeBO 3 (M is a transition metal
  • any metal oxide used as a positive electrode active material may have the above composition formula as a basic composition, and one obtained by replacing the metal element contained in the basic composition with another metal element can also be used.
  • a positive electrode active material a positive electrode active material containing no lithium ion contributing to charge and discharge, for example, a simple substance of sulfur (S), a compound obtained by complexing sulfur and carbon, a metal sulfide such as TiS 2 , V 2 O 5 , oxides such as MnO 2 , polyanilines and anthraquinones, compounds containing these aromatics in the chemical structure, conjugated materials such as conjugated diacetic acid organic substances, and other known materials can also be used.
  • S simple substance of sulfur
  • a metal sulfide such as TiS 2 , V 2 O 5
  • oxides such as MnO 2
  • polyanilines and anthraquinones compounds containing these aromatics in the chemical structure
  • conjugated materials such as conjugated diacetic acid organic substances, and other known materials
  • a compound having a stable radical such as nitroxide, nitronyl nitroxide, galvinoxyl, phenoxyl or the like may be adopted as the positive electrode active material.
  • a positive electrode active material containing no lithium it is necessary to add ions to the positive electrode and / or the negative electrode by a known method.
  • a metal or a compound containing the ions may be used.
  • the positive electrode active material layer In order to form the positive electrode active material layer on the surface of the current collector, a collection of conventionally known methods such as roll coating method, die coating method, dip coating method, doctor blade method, spray coating method and curtain coating method is performed.
  • the positive electrode active material may be applied to the surface of the current collector.
  • a composition for forming an active material layer containing a positive electrode active material and, if necessary, a binder and a conductive auxiliary agent is prepared, and a suitable solvent is added to the composition to form a paste, and then current collection is performed. Apply to the surface of the body and dry.
  • the solvent include organic solvents such as N-methyl-2-pyrrolidone, methanol and methyl isobutyl ketone, and water.
  • the dried positive electrode may be compressed to increase the electrode density.
  • the electrolytic solution is one in which a lithium metal salt which is an electrolyte is dissolved in an organic solvent.
  • the electrolyte is not particularly limited.
  • an organic solvent use is made of one or more selected from aprotic organic solvents such as propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), etc.
  • a lithium metal salt soluble in an organic solvent such as LiPF 6 , LiBF 4 , LiAsF 6 , LiI, LiClO 4 and LiCF 3 SO 3 can be used.
  • an electrolytic solution for example, 0.5 mol / L to 1.7 mol of lithium metal salt such as LiClO 4 , LiPF 6 , LiBF 4 , LiCF 3 SO 3 and the like in an organic solvent such as ethylene carbonate, dimethyl carbonate, propylene carbonate, dimethyl carbonate It is possible to use a solution dissolved at a concentration of about / L.
  • lithium metal salt such as LiClO 4 , LiPF 6 , LiBF 4 , LiCF 3 SO 3 and the like
  • organic solvent such as ethylene carbonate, dimethyl carbonate, propylene carbonate, dimethyl carbonate
  • a separator is used for a lithium ion secondary battery as needed.
  • the separator separates the positive electrode and the negative electrode, and allows lithium ions to pass while preventing a short circuit of the current due to the contact of the both electrodes.
  • synthetic resins such as polytetrafluoroethylene, polypropylene, polyethylene, polyimide, polyamide, polyaramid (Aromatic polyamide), polyester, polyacrylonitrile, etc., polysaccharides such as cellulose and amylose, natural substances such as fibroin, keratin, lignin and suberin Examples thereof include porous bodies, non-woven fabrics, and woven fabrics using one or more kinds of electrically insulating materials such as polymers and ceramics.
  • the separator may have a multilayer structure.
  • a separator is sandwiched between the positive electrode and the negative electrode as necessary to form an electrode body.
  • the electrode body may be any of a laminated type in which the positive electrode, the separator and the negative electrode are stacked, or a wound type in which the positive electrode, the separator and the negative electrode are wound.
  • the shape of the power storage device of the present invention is not particularly limited, and various shapes such as a cylindrical shape, a square shape, a coin shape, and a laminate type can be adopted.
  • a lithium ion secondary battery as a power storage device of the present invention may be mounted on a vehicle.
  • the vehicle may be a vehicle using electric energy from a lithium ion secondary battery for all or part of its power source, and may be, for example, an electric vehicle, a hybrid vehicle, or the like.
  • a lithium ion secondary battery is mounted on a vehicle, a plurality of lithium ion secondary batteries may be connected in series to form a battery pack.
  • various household appliances driven by a battery such as a personal computer and a mobile communication apparatus, as well as a vehicle, an office apparatus, an industrial apparatus and the like can be mentioned.
  • the negative electrode provided with the negative electrode active material of the present invention can be used in wind power generation, solar power generation, hydroelectric power generation, storage devices and power smoothing devices of electric power systems, power sources for power of ships and the like and / or auxiliary equipment.
  • Example 1 70 ml of a 36% by weight aqueous HCl solution was brought to 0 ° C. in an ice bath, and 5 g of calcium disilicide (CaSi 2 ) was added thereto in an argon gas flow and stirred. After confirming that the bubbling was completed, the temperature was raised to room temperature and stirred at room temperature for another 3 hours. At this time, yellow powder floated.
  • CaSi 2 calcium disilicide
  • the resulting mixed solution was allowed to stand for 30 minutes, and then crystalline silicon was removed by decantation, followed by filtration. The residue was washed 3 times with 30 ml of distilled water, then with 30 ml of ethanol and dried under vacuum to obtain 3 g of layered polysilane.
  • the obtained layered polysilane was heat-treated at 500 ° C. for 1 hour in argon gas in which the amount of O 2 was 1% by volume or less.
  • FIG. 3 shows an XRD spectrum
  • sharp peaks correspond to crystalline silicon
  • broad peaks correspond to other silicon such as amorphous silicon. From the area ratio of these peaks, the content of crystalline silicon to total silicon was calculated to be 27.1%.
  • a slurry was prepared by mixing 45 parts by mass of the obtained nanosilicon powder, 40 parts by mass of natural graphite powder, 5 parts by mass of acetylene black, and 33 parts by mass of a binder solution.
  • a binder solution a solution in which 30% by mass of polyamideimide (PAI) is dissolved in N-methyl-2-pyrrolidone (NMP) is used.
  • PAI polyamideimide
  • NMP N-methyl-2-pyrrolidone
  • the slurry was applied to the surface of an electrolytic copper foil (current collector) having a thickness of about 20 ⁇ m using a doctor blade to form a negative electrode active material layer on the copper foil. Thereafter, the current collector and the negative electrode active material layer were firmly and closely bonded by a roll press. This was vacuum dried at 200 ° C. for 2 hours to form a negative electrode having a thickness of 16 ⁇ m of the negative electrode active material layer.
  • a lithium ion secondary battery (half cell) was produced using the negative electrode produced according to the above procedure as an evaluation electrode.
  • the counter electrode was a metal lithium foil (thickness 500 ⁇ m).
  • the counter electrode was cut into a diameter of 12 mm, and the evaluation electrode was cut into a diameter of 11 mm, and a separator (a glass filter manufactured by Hoechst Celanese and "Celgard 2400" manufactured by Celgard) was interposed therebetween to obtain an electrode body battery.
  • the electrode battery was housed in a battery case (CR2032 type coin battery member, manufactured by Takasen Co., Ltd.).
  • a non-aqueous electrolytic solution in which LiPF 6 is dissolved at a concentration of 1 M in a mixed solvent of ethylene carbonate and diethyl carbonate mixed at 1: 1 (volume ratio) is sealed, and the battery case is sealed. 1 lithium ion secondary battery was obtained.
  • Example 2 70 ml of a 36% by weight aqueous HCl solution was brought to 10 ° C. in an ice bath, and 5 g of calcium disilicide (CaSi 2 ) was added thereto in an argon gas flow and stirred. After confirming that the bubbling was completed, the temperature was raised to room temperature and stirred at room temperature for another 3 hours. At this time, yellow powder floated.
  • CaSi 2 calcium disilicide
  • layered polysilane before treatment a layered polysilane
  • the layered polysilane before treatment was dispersed in ion exchange water to a concentration of 10% by weight, and centrifuged at 3000 rpm for 5 minutes in a centrifuge to remove the precipitate. After filtering the obtained mixture, the residue was washed with 30 ml of ethanol and vacuum dried to obtain 3 g of layered polysilane after treatment.
  • the obtained layered polysilane was heat-treated at 500 ° C. for 1 hour in argon gas in which the amount of O 2 was 1% by volume or less.
  • Lithium ion secondary battery A lithium ion secondary battery of Example 2 was produced in the same manner as in Example 1 except that the nanosilicon powder of Example 2 was used as the negative electrode active material.
  • Example 3 70 ml of a 36% by weight aqueous HCl solution was brought to 10 ° C. in an ice bath, and 5 g of calcium disilicide (CaSi 2 ) was added thereto in an argon gas flow and stirred. After confirming that the bubbling was completed, the temperature was raised to room temperature and stirred at room temperature for another 3 hours. At this time, yellow powder floated.
  • CaSi 2 calcium disilicide
  • the resulting mixed solution was allowed to stand for 5 minutes, and then crystalline silicon was removed by decantation, followed by filtration. The residue was washed 3 times with 30 ml of distilled water, then with 30 ml of ethanol and dried under vacuum to obtain 3 g of layered polysilane.
  • the obtained layered polysilane was heat-treated at 500 ° C. for 1 hour in argon gas in which the amount of O 2 was 1% by volume or less.
  • Lithium ion secondary battery A lithium ion secondary battery of Example 3 was produced in the same manner as in Example 1 except that the nanosilicon powder of Example 3 was used as the negative electrode active material.
  • Example 4 70 ml of a 36% by weight aqueous HCl solution was brought to 10 ° C. in an ice bath, and 5 g of calcium disilicide (CaSi 2 ) was added thereto in an argon gas flow and stirred. After confirming that the bubbling was completed, the temperature was raised to room temperature and stirred at room temperature for another 3 hours. At this time, yellow powder floated.
  • CaSi 2 calcium disilicide
  • the resulting mixed solution was filtered and then washed with a 5% by mass aqueous sodium hydroxide solution. Subsequently, filtration was performed, and the residue was washed 3 times with 30 ml of distilled water, then with 30 ml of ethanol, and vacuum dried to obtain 3 g of layered polysilane.
  • the obtained layered polysilane was heat-treated at 500 ° C. for 1 hour in argon gas in which the amount of O 2 was 1% by volume or less.
  • Lithium ion secondary battery A lithium ion secondary battery of Example 4 was produced in the same manner as in Example 1 except that the nanosilicon powder of Example 4 was used as the negative electrode active material.
  • Comparative Example 1 70 ml of a 36% by weight aqueous HCl solution was brought to 10 ° C. in an ice bath, and 5 g of calcium disilicide (CaSi 2 ) was added thereto in an argon gas flow and stirred. After confirming that the bubbling was completed, the temperature was raised to room temperature and stirred at room temperature for another 3 hours. At this time, yellow powder floated.
  • CaSi 2 calcium disilicide
  • the resulting mixed solution was filtered and the residue was washed 3 times with 30 ml of distilled water, then with 30 ml of ethanol and dried under vacuum to obtain 4 g of layered polysilane.
  • the obtained layered polysilane was heat-treated at 500 ° C. for 1 hour in argon gas in which the amount of O 2 was 1% by volume or less.
  • Example 1 ⁇ X-ray diffraction analysis> The obtained nano silicon powder was subjected to X-ray diffraction measurement in the same manner as in Example 1.
  • FIG. 7 shows an XRD spectrum
  • the calculated content of crystalline silicon is shown in Table 1.
  • Lithium ion secondary battery A lithium ion secondary battery of Comparative Example 1 was produced in the same manner as in Example 1 except that the nanosilicon powder of Comparative Example 1 was used as the negative electrode active material.
  • the termination voltage of charge is 1.0 V at the Li counter electrode
  • the termination voltage of discharge is 0.01 V at the Li counter electrode
  • charging is performed at a constant current of 0.2 mA.
  • Discharge was performed, and charge capacity and discharge capacity were measured. The charge capacity at this time was taken as the initial capacity, and the charge capacity / discharge capacity was taken as the initial efficiency.
  • Table 1 The results are shown in Table 1.
  • the discharge capacity retention rate is a value obtained by dividing the discharge capacity at the N cycle by the discharge capacity at the first cycle ((discharge capacity at the N cycle) / (discharge capacity at the first cycle) x 100). . Further, a graph of the number of cycles and the capacity retention rate of Example 1 and Comparative Example 1 is shown in FIG.
  • the lithium ion secondary battery using the negative electrode active material of this example for the negative electrode has a large improvement in the capacity retention rate as compared to the lithium ion secondary battery of Comparative Example 1. It is clear that this is due to the low content of crystalline silicon in the negative electrode active material. Although the lithium ion secondary battery according to Example 4 has an extremely high capacity retention rate, the initial capacity and the initial efficiency are lower than those of the other examples, but this is due to the high oxygen content. It is thought that
  • the negative electrode active material of the present invention can be used for the negative electrode of a storage device such as a secondary battery, an electric double layer capacitor, or a lithium ion capacitor.
  • a storage device such as a secondary battery, an electric double layer capacitor, or a lithium ion capacitor.
  • the storage device is useful as a non-aqueous secondary battery used for driving motors of electric vehicles and hybrid vehicles, personal computers, portable communication devices, home appliances, office devices, industrial devices, etc. It can be used optimally for the motor drive of electric vehicles and hybrid vehicles that require a large output.

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Abstract

L'invention concerne une substance active d'électrode négative formée à partir de nanosilicium présentant un niveau de rétention de capacité élevé. Un dispositif de stockage d'électricité présentant d'excellentes propriétés de cycle telles qu'un niveau de rétention de capacité peut être obtenu par utilisation, en tant que substance active d'électrode négative, de nanosilicium présentant une teneur en silicium cristallin qui est inférieure ou égal à 40% du silicium total.
PCT/JP2014/005424 2013-11-05 2014-10-27 Substance active d'électrode négative et dispositif de stockage d'électricité Ceased WO2015068351A1 (fr)

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JP6459798B2 (ja) * 2015-06-24 2019-01-30 株式会社豊田自動織機 炭素含有シリコン材料及びその製造方法並びに炭素含有シリコン材料を具備する二次電池
JP6376054B2 (ja) * 2015-06-24 2018-08-22 株式会社豊田自動織機 シリコン材料及びその製造方法並びにシリコン材料を具備する二次電池
JP6878967B2 (ja) * 2017-03-09 2021-06-02 株式会社豊田自動織機 負極材料の製造方法
CN116885105A (zh) * 2021-09-08 2023-10-13 珠海冠宇电池股份有限公司 一种硅负极体系的锂离子电池和电子装置

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