JP2011124058A - Lithium-ion secondary battery, vehicle and battery-equipped apparatus with the battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery which prevents a lithium ion from entering an outward portion of a negative electrode active material layer and suppresses a decrease in battery capacity, a vehicle equipped with this lithium ion secondary battery, and a battery-equipped device. provide.
SOLUTION: A lithium ion secondary battery 1 includes a positive electrode plate 30 including positive electrode active material layers 31 and 35 disposed on both surfaces of a positive electrode current collector plate 38, and a negative electrode disposed on both surfaces of a negative electrode current collector plate 28. The negative electrode plate 20 including the active material layers 21 and 25, and the separator 50, the power generation element 10 including the separator between the positive electrode plate and the negative electrode plate, and held by the power generation element, An electrolyte solution 60 containing lithium ions, and any part of the positive electrode active material layer faces the negative electrode active material layer, and faces the outside of the power generation element without facing the positive electrode plate in the negative electrode active material layer. The outward portion 21B is subjected to a penetration preventing process for preventing the penetration of the electrolytic solution.
[Selection] Figure 6

Description

  The present invention relates to a lithium ion secondary battery including a power generation element having a separator between a positive electrode plate and a negative electrode plate, a vehicle equipped with the lithium ion secondary battery, and a battery-equipped device.

In recent years, lithium ion secondary batteries (hereinafter also simply referred to as batteries) have been used as power sources for driving portable electronic devices such as hybrid cars, notebook computers, and video camcorders.
Patent Document 1 discloses a positive electrode mixture (positive electrode active material layer) and / or a non-aqueous secondary battery (battery) in which a negative electrode (negative electrode plate) has a larger dimension than a positive electrode (positive electrode plate). Or the nonaqueous secondary battery (battery) formed by coat | covering the edge part 1-10mm of the mixture (negative electrode active material layer) of a negative electrode with a lithium ion impermeable material is disclosed. Thereby, the effect which suppresses the self-discharge of the nonaqueous secondary battery (battery) in the charged state arises.

JP-A-9-134719

  By the way, not only the nonaqueous secondary battery of patent document 1, but the negative electrode plate (negative electrode active material layer) of a battery is provided in order to insert and discharge | release lithium ion to a negative electrode active material by charging / discharging. . However, for the convenience of manufacture, an outwardly facing portion of the negative electrode active material layer that faces the outside of the power generation element including the positive electrode plate, the negative electrode plate, and the separator may be provided without facing the positive electrode plate. Examples of such outward facing portions include, for example, the outermost active material layer of the negative electrode plate that forms part of a wound-type power generation element, the portion located on the outermost periphery, and the negative power generation element that forms a stacked power generation element. Among the electrode plates, an outwardly facing negative electrode active material layer of the outermost negative electrode plate located on the outermost side in the stacking direction can be mentioned.

However, lithium ions may move to the outward portion as well, for example, due to diffusion from other parts of the negative electrode active material layer or wraparound from the positive electrode active material layer. However, since the outward portion does not face the positive electrode active material layer (positive electrode plate), the lithium ions once entering the outward portion are unlikely to be released from the outward portion when the battery is discharged. Therefore, the amount of lithium ions that can be used for the battery reaction is reduced, that is, the battery capacity is reduced by the amount of lithium ions entering the outward portion.
In addition, the battery of patent document 1 has neither description about the subject mentioned above about the outward part of a negative electrode active material layer, nor the technique for solving it.

  The present invention has been made in view of such problems, and prevents lithium ions from entering the outward portion of the negative electrode active material layer, thereby suppressing a decrease in battery capacity. It aims at providing the vehicle and battery mounting apparatus which mount a lithium ion secondary battery.

  One embodiment of the present invention includes a positive electrode current collector plate, a positive electrode plate including a positive electrode active material layer disposed on both surfaces of the positive electrode current collector plate, a negative electrode current collector plate, and both surfaces of the negative electrode current collector plate A negative electrode plate including a negative electrode active material layer disposed on the separator, and a power generation element including the separator between the positive electrode plate and the negative electrode plate, and the power generation element An electrolyte containing lithium ions, and a lithium ion secondary battery in which any part of the positive electrode active material layer is opposed to the negative electrode active material layer, of the negative electrode active material layer, It is a lithium ion secondary battery in which a permeation preventing treatment for preventing permeation of the electrolytic solution is applied to at least a part of the outward portion facing the outside of the power generation element without facing the positive electrode plate.

  In the battery described above, since the permeation prevention treatment is performed on at least a part of the outward portion of the negative electrode active material layer, the electrolytic solution does not permeate into this portion. For this reason, it is possible to suppress or prevent lithium ions from entering the outward portion through the electrolytic solution and remaining occluded in the negative electrode active material layer. Thus, a battery in which a decrease in battery capacity is suppressed can be obtained.

  Each of the power generation elements includes a strip-shaped positive electrode plate, a negative electrode plate, and a separator, which are wound around a winding axis, or a positive power generation element with a separator interposed therebetween. A laminated power generation element formed by alternately laminating electrode plates and negative electrode plates can be mentioned. Further, as the outward portion, for example, when the power generation element is a wound power generation element and the negative electrode active material layers are provided on both surfaces of the negative electrode current collector plate, the outer side disposed on the outer surface of the negative electrode current collector plate Of the negative electrode active material layer, an outermost outermost portion located at the outermost periphery is exemplified. Further, when the power generating element is a stacked power generating element, the outermost negative electrode plate located on the outermost side in the stacking direction of the stacked power generating element among the negative electrode plates is positioned on the outer side in the stacking direction than the negative current collector plate. The outermost negative electrode active material layer located is mentioned.

Further, as the permeation prevention treatment, for example, a coating material (described below) dissolved or dispersed in a solvent is applied to the outward portion of the negative electrode active material layer and dried. Examples of the treatment include sticking, then heat welding, rubbing the coating material on the outward portion, spraying a powdery coating material on the outward portion, and then heat welding.
Examples of the coating material include polyolefin, polystyrene, polybutadiene, hydrogenated polybutadiene, polyvinyl resin, polyether, polyester, polyimide, polysulfide, epoxy resin, fluorine resin, silicon resin, urethane resin, phenol resin, cellulose derivative, And liquid repellent materials such as paraffinic hydrocarbons, fluorinated paraffins, and fluorosilicones.

  Furthermore, in the above-described lithium ion secondary battery, the power generation element includes the positive electrode plate, the negative electrode plate, and the separator, each of which has a strip shape, and the positive electrode plate, the negative electrode plate, and the above A winding type power generation element formed by winding a separator around a winding axis, wherein the positive electrode plate is the positive electrode active material layer and is disposed on the inner side surface of the positive electrode current collector plate The negative electrode plate is the negative electrode active material layer, and the inner side of the negative electrode current collector plate is disposed on the inner side surface of the negative electrode active material layer. A negative electrode active material layer; and an outer negative electrode active material layer disposed on an outer surface, wherein the outer positive electrode active material layer faces the inner negative electrode active material layer, and the outward portion is formed by the outer negative electrode active material layer. Of these, lithium ion It may be a battery.

  In the above-described lithium ion secondary battery, the power generation element is the above-described wound power generation element, and the outward portion is the above-described outermost outward portion. That is, this battery includes a wound power generation element, and permeation preventing treatment is performed on at least a part of the outermost outer circumferential outward portion of the outer negative electrode active material layer. Therefore, the penetration of the electrolytic solution into this portion can be prevented. For this reason, it is possible to suppress or prevent lithium ions from entering through the electrolytic solution and remaining occluded in the negative electrode active material layer in at least a portion of the outermost outer peripheral portion that has been subjected to the permeation prevention treatment. Thus, a battery in which a decrease in battery capacity is suppressed can be obtained.

  Further, in the lithium ion secondary battery described above, the inner negative electrode active material layer has an inner non-opposing portion where the outer positive electrode active material layer facing through the separator does not exist at a winding end portion of the inner negative electrode active material layer. And it is good to set it as the lithium ion secondary battery by which the said permeation | blocking prevention process is given also to at least one part of the said inner non-opposing part.

  By the way, the inner side negative electrode active material layer may be provided with an inner non-facing portion where the outer side positive electrode active material layer opposed via the separator does not exist at the winding end portion of the wound power generation element. This is because, when the positive electrode active material layer is larger than the negative electrode active material layer, lithium ions released from the positive electrode active material layer are concentrated on the end of the negative electrode active material layer, thereby preventing a problem that metallic lithium is deposited. It is. However, similarly to the outward portion described above, the inner non-opposing portion is diffused from other parts of the negative electrode active material layer or wraps around from the positive electrode active material layer, so that lithium ions enter the negative electrode active material layer. It remains occluded. Therefore, as with the outward portion, the battery capacity is reduced by the amount of lithium ions that have entered the inner non-opposing portion.

  On the other hand, in the above-mentioned battery, at least a part of the inner non-facing portion of the inner negative electrode active material layer is subjected to permeation prevention treatment. Therefore, lithium ions can be prevented from entering the inner non-opposing portion through the electrolytic solution and remaining occluded in the negative electrode active material layer. Thus, a battery in which a decrease in battery capacity is reliably suppressed can be obtained.

  Alternatively, in the lithium ion secondary battery described above, the power generation element is a stacked power generation element in which the positive electrode plate and the negative electrode plate are alternately stacked with the separator interposed therebetween, The outward portion is an outermost negative electrode plate positioned on the outermost side in the stacking direction among the negative electrode plates, and is an outermost negative electrode active material layer positioned on the outer side in the stacking direction than the negative electrode current collector plate It is preferable to use an ion secondary battery.

  In the above-described lithium ion secondary battery, the power generation element is the above-described stacked power generation element, and the outward portion is the above-described outermost negative electrode active material layer. That is, this battery includes a laminated power generation element, and at least a part of the outermost negative electrode active material layer is subjected to permeation prevention treatment. Therefore, the penetration of the electrolytic solution into this portion can be prevented. For this reason, it is possible to suppress or prevent lithium ions from entering through the electrolyte and remaining occluded in the negative electrode active material layer in at least a portion of the outermost negative electrode active material layer that has been subjected to the permeation prevention treatment. . Thus, a battery in which a decrease in battery capacity is suppressed can be obtained.

  Furthermore, any of the lithium ion secondary batteries described above may be a lithium ion secondary battery in which the permeation preventing process is performed on the periphery of the outward portion.

According to the inventors' research, it has been found that lithium ions moving from the positive electrode active material layer to the outward portion are likely to enter from the periphery of the outward portion.
Based on this, in the battery described above, the permeation preventing process is performed on the periphery of the outward portion, so that lithium ions can be more reliably reduced from entering the outward portion.

  Alternatively, any one of the above-described lithium ion secondary batteries may be a lithium ion secondary battery in which the entire outward portion is subjected to the permeation prevention treatment.

  In the battery described above, since the penetration preventing process is performed on the entire outward portion, it is possible to reliably prevent lithium ions from entering the outward portion.

  Alternatively, another aspect of the present invention is a vehicle in which the lithium ion secondary battery described in any of the above is mounted and the electric energy stored in the lithium ion secondary battery is used for all or part of the power source. is there.

  Since the above-mentioned vehicle is equipped with a battery that suppresses a decrease in battery capacity, it can be a vehicle having a power source with stable performance.

  The vehicle may be a vehicle that uses electric energy from a battery as a whole or a part of a power source. For example, an electric vehicle, a hybrid vehicle, a plug-in hybrid vehicle, a hybrid railway vehicle, a forklift, an electric wheelchair, electric Examples include assist bicycles and electric scooters.

  Alternatively, according to another aspect of the present invention, there is provided a battery in which the lithium ion secondary battery according to any one of the foregoing is mounted and the electric energy stored in the lithium ion secondary battery is used for all or part of the driving energy source. On-board equipment.

  Since the battery-mounted device described above is mounted with a battery in which a decrease in battery capacity is suppressed, it can be a battery-mounted device having a drive energy source with stable performance.

  In addition, as a battery mounting apparatus, what is necessary is just an apparatus which mounts a battery and uses this for all or one part of an energy source, for example, a personal computer, a mobile telephone, a battery drive electric tool, an uninterruptible power supply, etc. And various home appliances driven by batteries, office equipment, and industrial equipment.

It is a perspective view of the battery concerning Embodiment 1, modification 1,2. It is a perspective view of the positive electrode plate of Embodiment 1, modification 1,2. It is a perspective view of the negative electrode plate of Embodiment 1 and Modification 2. 3 is a perspective view of a negative electrode plate according to Embodiment 1. FIG. It is sectional drawing (AA cross section in FIG. 1) of the electric power generation element of Embodiment 1, modification 1,2. It is an expanded sectional view (B section in Drawing 5) of the electric power generation element of Embodiment 1. It is a perspective view of the negative electrode plate of modification 1. It is a perspective view of the negative electrode plate of modification 1. It is an expanded sectional view (B section in Drawing 5) of the electric power generation element of modification 1. It is a perspective view of the negative electrode plate of modification 2. 6 is a perspective view of a battery according to Embodiment 2. FIG. It is sectional drawing (CC cross section in FIG. 11) of the electric power generation element of Embodiment 2. FIG. It is explanatory drawing of the vehicle concerning Embodiment 3. FIG. It is explanatory drawing of the hammer drill concerning Embodiment 4.

(Embodiment 1)
Next, Embodiment 1 of the present invention will be described with reference to the drawings.
First, the battery 1 according to the first embodiment will be described with reference to FIG.
The battery 1 includes a belt-like positive electrode plate 30, a negative electrode plate 20, and a separator 50, and a power generation element 10 that includes the separator 50 between the positive electrode plate 30 and the negative electrode plate 20, This is a lithium ion secondary battery that is held by the power generation element 10 and includes an electrolytic solution 60 containing lithium ions (see FIG. 1). In addition, the battery 1 accommodates the electric power generation element 10 in the battery case 80, as shown in FIG.

  The battery case 80 has a battery case body 81 and a sealing lid 82 both made of aluminum. Among these, the battery case main body 81 has a bottomed rectangular box shape, and an insulating film (not shown) made of resin and bent into a box shape is interposed between the battery case 80 and the power generation element 10. The sealing lid 82 has a rectangular plate shape, closes the opening of the battery case body 81, and is welded to the battery case body 81. Of the positive electrode current collecting member 91 and the negative electrode current collecting member 92 connected to the power generation element 10, the positive electrode terminal portion 91 </ b> A and the negative electrode terminal portion 92 </ b> A located at the tips of the sealing lid 82 pass through, respectively. 1 protrudes from the lid surface 82a facing upward. Insulating members 95 made of insulating resin are interposed between the positive electrode terminal portion 91A and the negative electrode terminal portion 92A and the sealing lid 82 to insulate each other. Further, a rectangular plate-shaped safety valve 97 is also sealed on the sealing lid 82.

In addition, the electrolytic solution 60 was prepared by adding LiPF ₆ as a solute to a mixed organic solvent in which ethylene carbonate (EC) and diethyl carbonate (DEC) were adjusted to EC: EMC = 3: 7 by volume ratio, and lithium ions were added. This is a non-aqueous electrolyte having a concentration of 1 mol / l.

  Each of the power generating elements 10 includes a strip-shaped positive electrode plate 30, a negative electrode plate 20, and a separator 50. The positive electrode plate 30, the negative electrode plate 20, and the separator 50 are flattened around the winding axis AX. This is a wound power generation element wound in a shape (see FIG. 1). The positive electrode plate 30 and the negative electrode plate 20 of the power generation element 10 are respectively joined to a plate-like positive current collector 91 or negative current collector 92 bent in a crank shape (see FIG. 1). Among these, the strip-shaped separator 50 made of polyethylene is interposed between the positive electrode plate 30 and the negative electrode plate 20 to separate them.

Further, as shown in the perspective view of FIG. 2, the positive electrode plate 30 has a strip shape extending in the longitudinal direction DA. 38Y) and two positive electrode active material layers 31 and 35 arranged in a strip shape. The aluminum foil 38 has an inner surface 38Y that faces the inside of the power generation element 10, that is, the winding axis AX side, and an outer surface 38X that faces the outside of the power generation element 10. Moreover, as shown in FIG. 5 which is sectional drawing (AA cross section of FIG. 1) of the electric power generation element 10, and FIG. 6 which is expanded sectional drawing (B section of FIG. 5), among positive electrode active material layers, The aluminum foil 38 disposed on the outer surface 38X is referred to as an outer positive electrode active material layer 31, and the aluminum foil 38 disposed on the inner surface 38Y is referred to as an inner positive electrode active material layer 35.
Both the outer positive electrode active material layer 31 and the inner positive electrode active material layer 35 are positive electrode active material particles (not shown) made of LiCoO ₂ , a conductive material (not shown) made of acetylene black, and polyvinylidene fluoride (PVDF). And a binding material (not shown).

3 and 4, the negative electrode plate 20 has a strip shape extending in the longitudinal direction DA, and is made of a copper foil 28 made of copper and both surfaces of the copper foil 28 (the outer surface 28X, which will be described below). The side surface 28Y) has two negative electrode active material layers 21 and 25 arranged in a strip shape. The copper foil 28 includes an inner side surface 28 </ b> Y that faces the inside of the power generation element 10 and an outer side surface 28 </ b> X that faces the outside of the power generation element 10, similarly to the aluminum foil 38. 5 and 6, among the negative electrode active material layers, the one disposed on the outer surface 28X of the copper foil 28 is the outer negative electrode active material layer 21, and the one disposed on the inner side surface 28Y is the inner negative electrode. The active material layer 25 is used.
Each of the outer negative electrode active material layer 21 and the inner negative electrode active material layer 25 includes negative electrode active material particles (not shown) made of graphite and a binder (not shown) made of PVDF.

Among these, the inner negative electrode active material layer 25 is disposed opposite to the outer positive electrode active material layer 31 of the positive electrode plate 30 with the separator 50 interposed therebetween, as shown in FIG. Note that the inner negative electrode active material layer 25 has an inner opposite portion 25A that faces the outer positive electrode active material layer 31 and an outer positive electrode active material that faces the outer end portion of the inner negative electrode active material layer 25 (portion B in FIG. 5). And an inner non-facing portion 25B in which the material layer 31 does not exist.
Conversely, the outer positive electrode active material layer 31 is opposed to the inner negative electrode active material layer 25 at any part. Thus, in the battery 1 according to the first embodiment, the inner negative electrode active material layer 25 is larger (longer) in the longitudinal direction DA than the outer positive electrode active material layer 31 by the inner non-facing portion 25B. Thus, when the battery 1 is charged, metallic lithium is prevented from being deposited at the end of the inner negative electrode active material layer 25 of the negative electrode plate 20 on the winding end side.

On the other hand, as shown in FIG. 6, the outer negative electrode active material layer 21 is disposed opposite to the inner positive electrode active material layer 35 of the positive electrode plate 30 with a separator 50 interposed therebetween. The outer negative electrode active material layer 21 faces the outer positive portion 21A facing the inner positive electrode active material layer 35 and the outer side of the power generation element 10 without facing the positive electrode plate 30. It has the outermost outer periphery outward part 21B located in the outermost periphery.
On the contrary, the inner cathode active material layer 35 is opposed to the outer anode active material layer 21 at any part.

  Furthermore, in the battery 1 of the first embodiment, the permeation preventing process for preventing the permeation of the electrolytic solution 60 is performed on the entire outermost outward portion 21B. Specifically, a process in which a fluororesin polytetrafluoroethylene dispersed in a solvent is applied to the outermost outer peripheral portion 21B and dried by heating. By this permeation prevention treatment, a polytetrafluoroethylene film is formed on the surface of the outermost outer peripheral portion 21B. As a result, the electrolyte solution 60 is prevented from penetrating into the outermost outer peripheral portion 21B. For this reason, it is possible to prevent lithium ions from entering the outermost outer circumferential outward portion 21 </ b> B through the electrolytic solution 60.

In addition, the inventors of the battery 1 of the first embodiment, that is, the battery in which the outermost outer circumferential outward portion 21B of the negative electrode active material layer 21 is subjected to the permeation prevention process of the electrolyte solution 60, and the permeation prevention process For the comparative battery C1 not subjected to the above, the change in battery capacity was examined.
Specifically, a battery 1 in which a dispersion of polytetrafluoroethylene is applied to the outermost outwardly facing portion 21B and dried, and a comparative battery C1 in which neither of the negative electrode active material layers is subjected to permeation prevention treatment Prepared. Each of these batteries is fully charged in an environment of 25 ° C. (that is, a constant current charge to 4.1 V (full charge voltage) at a current value of 1 C), and then the current value is kept to 0.05 C while maintaining the voltage. The battery was gradually lowered and charged for 60 minutes. Next, for each fully charged battery, constant current discharge was performed until the current value of 1C reached 2.5 V, and the discharged discharge capacity (initial discharge capacity) was measured.
After the measurement, each battery was again fully charged in an environment of 25 ° C., and left to stand in an environment of 25 ° C. for 50 days.
Thereafter, the discharge capacity (discharge capacity after standing) of each battery was measured, and the change in the discharge capacity of each battery before and after standing was examined. Specifically, the battery capacity maintenance rate of each battery was calculated by dividing the static discharge capacity after standing by the initial discharge capacity.

The battery capacity maintenance rate of the comparative battery C1 was 90.0%, whereas the battery capacity maintenance rate of the battery 1 was 96.5%. The battery 1 had a battery capacity higher than that of the comparative battery C1. It can be seen that the decrease can be suppressed. This is because lithium ions enter through the electrolyte into the outermost part of the outermost periphery of the comparative battery C1, which has not been subjected to permeation prevention treatment, due to diffusion or the like from other parts of the negative electrode active material layer during standing. However, since this lithium ion has entered the outermost outer peripheral portion of the outer negative electrode active material layer that does not face the positive electrode plate, it is not easily released from the battery during discharge, and is not used for the battery reaction. It remains occluded in the outer circumferential outward portion.
On the other hand, the electrolyte solution 60 does not permeate into the outermost peripheral outward portion 21B of the battery 1 subjected to the permeation prevention process. Since the lithium ions move in the electrolytic solution 60, the lithium ions enter the outermost outer peripheral portion 21 </ b> B where the electrolytic solution 60 does not permeate while standing, and enter the negative electrode active material there. Lithium ions are not inserted. Thus, it is considered that the decrease in the battery capacity of the battery 1 is suppressed as compared with the comparative battery C1.

  As described above, the battery 1 according to the first embodiment includes the wound power generation element 10, and the outermost outward facing portion 21 </ b> B of the outer negative electrode active material layer 21 is subjected to the permeation prevention process. The electrolyte solution 60 does not permeate. For this reason, it is possible to prevent lithium ions from entering the outermost outward portion 21B through the electrolytic solution 60 and remaining occluded in the negative electrode active material layer (outer negative electrode active material layer 21). Thus, the battery 1 in which the decrease in battery capacity is suppressed can be obtained.

  In addition, since the permeation preventing process is performed on the entire outermost outward portion 21B, it is possible to reliably prevent lithium ions from entering the outermost outward portion 21B.

Next, a method for manufacturing the battery 1 according to the first embodiment will be described.
First, the negative electrode plate 20 is produced. Specifically, a paste (not shown) formed by mixing and kneading the negative electrode active material particles made of graphite described above in N-methyl-2-pyrrolidone (NMP) in which a binder made of PVDF is dissolved. Then, it was applied to the outer side surface 28X and the inner side surface 28Y of the strip-shaped copper foil 28 extending in the longitudinal direction DA and dried. Thereafter, the dried paste was compressed by a roll press (not shown) to form a densified negative electrode active material layer (outer negative electrode active material layer 21, inner negative electrode active material layer 25).
Next, a dispersion liquid (not shown) in which polytetrafluoroethylene is dispersed in a solvent is applied to the entire surface of the outer negative electrode active material layer 21 to be the outer non-facing portion 21B, heated and dried, and the negative electrode plate 20 (See FIGS. 3 and 4).

  On the other hand, a paste (not shown) obtained by adding and kneading positive electrode active material particles and a conductive material into NMP in which a binder is dissolved is used as an outer surface 38X of a strip-shaped aluminum foil 38 extending in the longitudinal direction DA and It was applied to the inner surface 38Y and dried. Then, the paste dried by the roll press which is not illustrated was compressed, and the positive electrode plate 30 which has a positive electrode active material layer (the outer side positive electrode active material layer 31, the inner side positive electrode active material layer 35) was produced (refer FIG. 2).

  The negative electrode plate 20 and the positive electrode plate 30 produced as described above are wound with a separator 50 interposed therebetween to obtain the power generation element 10. It should be noted that the outer positive active material layer 31 of the positive electrode plate 30 and the outer opposing portion of the outer negative electrode active material layer 21 via the separator 50 on the inner facing portion 25A of the inner negative electrode active material layer 25 of the negative electrode plate 20. The separator 50, the negative electrode plate 20, the separator 50, and the positive electrode plate 30 are stacked in this order so that the inner positive electrode active material layer 35 of the positive electrode plate 30 faces the 21A via the separator 50. .

  Thereafter, the negative electrode collector member 92 and the positive electrode collector member 91 are welded to the negative electrode plate 20 (copper foil 28) and the positive electrode plate 30 (aluminum foil 38), respectively, inserted into the battery case body 81, and the above-described electrolysis is performed. After injecting the liquid 60, the battery case body 81 is sealed with a sealing lid 82 by welding. Thus, the battery 1 is completed (see FIG. 1).

(Modification 1)
Next, the battery 101 according to the first modification of the present invention will be described with reference to FIGS.
Similar to the battery 1 according to the first embodiment, the battery 101 has an inner non-facing portion where there is no outer positive electrode active material layer facing through the separator at the winding end portion of the inner negative electrode active material layer. Yes. However, this battery is the same as the battery 1 except that the inner non-opposing portion is also subjected to a permeation preventing process.
Therefore, the description will be focused on differences from the battery 1 according to the first embodiment, and description of similar parts will be omitted or simplified. In addition, about the same part, the same effect is produced. In addition, the same contents are described with the same numbers.

The battery 101 according to the first modification has a belt-like positive electrode plate 30, a negative electrode plate 120, and a separator 50, and power generation is performed via the separator 50 between the positive electrode plate 30 and the negative electrode plate 120. It is a lithium ion secondary battery provided with the element 110 and the electrolyte solution 60 hold | maintained at this electric power generation element 110, and containing lithium ion (refer FIG. 1).
Among these, as shown in the perspective views of FIGS. 7 and 8, the negative electrode plate 120 is formed in a strip shape on the copper foil 28 similar to that of the first embodiment and on both surfaces (the outer surface 28X and the inner surface 28Y) of the copper foil 28, respectively. Two negative electrode active material layers (an outer negative electrode active material layer 21 and an inner negative electrode active material layer 125) are disposed. The outer negative electrode active material layer 21 and the inner negative electrode active material layer 125 are both made of negative electrode active material particles (not shown) made of graphite and a binder (not shown) made of PVDF, as in the first embodiment. Contains.

  Among these, the inner negative electrode active material layer 125 is disposed opposite to the outer positive electrode active material layer 31 of the positive electrode plate 30 via the separator 50 as shown in FIG. Note that the inner negative electrode active material layer 125 includes an inner opposite portion 125A that faces the outer cathode active material layer 31 and an outer electrode active material layer that faces the outer negative electrode active material layer 125 at a winding end portion (B portion in FIG. 5). And an inner non-facing portion 125B where the material layer 31 does not exist.

The inner non-facing portion 125B of the inner negative electrode active material layer 125 is different from the first embodiment in that the same permeation prevention treatment as that of the outermost outer peripheral portion 21B of the first embodiment is performed.
Specifically, the same treatment as that of the first embodiment in which polytetrafluoroethylene is dispersed in a solvent is applied to the entire inner non-facing portion 125B and is heated and dried. By this permeation prevention process, a polytetrafluoroethylene film is formed on the surface of the inner non-opposing portion 125B. Thus, the electrolyte solution 60 is prevented from penetrating into the inner non-opposing portion 125B together with the outermost outer peripheral portion 21B. For this reason, it is possible to prevent lithium ions from entering the inside non-opposing portion 125B through the electrolytic solution 60.
Regarding the battery 101, when the change in the battery capacity was examined in the same manner as the battery 1 of the first embodiment, the battery capacity was further prevented from lowering than the battery 1 as well as the comparative battery C1 of the comparative example. Confirmed that it will be.

  As described above, in the battery 101 according to the first modification, the entire inner non-facing portion 125B of the inner negative electrode active material layer 125 is subjected to the permeation prevention process. For this reason, similarly to the outermost outermost outward portion 21B, lithium ions are prevented from entering the inner non-opposing portion 125B through the electrolytic solution 60 and remaining occluded in the negative electrode active material layer (inner negative electrode active material layer 125). can do. Thus, the battery 101 in which the decrease in battery capacity is reliably suppressed can be obtained.

Next, a method for manufacturing the battery 101 according to the first modification will be described.
First, the negative electrode plate 120 is produced. Specifically, as in the first embodiment, a paste (not shown) obtained by adding and kneading negative electrode active material particles into NMP in which a binder is dissolved is used as an outer surface 28X of a strip-shaped copper foil 28 and It was applied to the inner side surface 28Y and dried. Thereafter, the dried paste was compressed by a roll press (not shown) to form a densified negative electrode active material layer (outer negative electrode active material layer 21, inner negative electrode active material layer 125).
Next, a dispersion liquid (not shown) in which polytetrafluoroethylene is dispersed in a solvent is applied to the entire surface of the outer non-facing portion 21B of the outer negative electrode active material layer 21 and the inner non-active portion of the inner negative electrode active material layer 125. It apply | coated to the whole surface of the opposing part 125B, it heat-dried, and the negative electrode plate 120 was produced (refer FIG. 7, 8).

The negative electrode plate 120 produced as described above and the positive electrode plate 30 produced in the same manner as in the first embodiment are wound with the separator 50 interposed therebetween to form the power generation element 110. It should be noted that the outer positive active material layer 31 of the positive electrode plate 30 and the outer opposing portion of the outer negative electrode active material layer 21 are disposed on the inner facing portion 125A of the inner negative electrode active material layer 125 of the negative electrode plate 120 via the separator 50. The separator 50, the negative electrode plate 20, the separator 50, and the positive electrode plate 30 are stacked in this order so that the inner positive electrode active material layer 35 of the positive electrode plate 30 faces the 21A via the separator 50. .
Thereafter, the battery 101 is completed in the same manner as in the first embodiment (see FIG. 1).

(Modification 2)
Next, a battery 201 according to the second modification of the present invention will be described with reference to FIGS.
This battery 201 is the same as the battery 1 according to the first embodiment described above except that a permeation prevention process is performed on the outer periphery of the outermost outer peripheral portion.

  As shown in the perspective views of FIGS. 3 and 10, the negative electrode plate 220 of the battery 201 has the same copper foil 28 as that of the first embodiment and both surfaces (the outer side surface 28 </ b> X and the inner side surface 28 </ b> Y) of the copper foil 28. It has two negative electrode active material layers (an outer negative electrode active material layer 221 and an inner negative electrode active material layer 25) arranged in a band shape. The outer negative electrode active material layer 221 and the inner negative electrode active material layer 25 are both negative electrode active material particles (not shown) made of graphite and a binder (not shown) made of PVDF, as in the first embodiment. )including.

  Among these, as shown in FIG. 10, the outer negative electrode active material layer 221 includes an outer facing portion 21A similar to that of the first embodiment and an outermost outer peripheral portion 221B adjacent to the longitudinal direction DA of the outer facing portion 21A. Have. Up to this point, the battery 1 is the same as that of the battery 1 according to the first embodiment. However, the outermost outer peripheral portion 221B is composed of a peripheral portion 221E located at its peripheral portion and a central portion 221C surrounded by the peripheral portion 221E.

And it differs from Embodiment 1 in the point that the penetration preventing process which prevents penetration of electrolyte solution 60 is given to peripheral part 221E of this outermost circumference outward part 221B.
Specifically, the peripheral portion 221E of the outermost outermost outward portion 221B is subjected to a process of applying polytetrafluoroethylene dispersed in a solvent and heating and drying, as in the first embodiment. By this permeation prevention treatment, a polytetrafluoroethylene film is formed on the surface of the peripheral edge portion 221E of the outermost peripheral outward portion 221B.

According to the study by the present inventors, lithium ions moving from the positive electrode active material layers 31 and 35 to the outermost outer periphery outward portion 221B are more peripheral than the central portion 221C in the outermost outer periphery outward portion 221B. It has moved toward 221E, and it has been found that it is easy to enter many places here.
On the other hand, in the battery 201 according to the second modification, since the permeation prevention process is performed on the peripheral edge portion 221E of the outermost outer periphery portion 221B, it is more likely that lithium ions enter the outermost outer periphery outward portion 221B. It can be surely reduced.

(Embodiment 2)
Next, a battery 301 according to Embodiment 2 of the present invention will be described with reference to FIGS.
The battery 301 is different from the battery 1 according to the first embodiment described above in that it has a stacked power generation element in which a plurality of positive electrode plates and a plurality of negative electrode plates are alternately stacked via separators.

  That is, the battery 301 is held by the power generation element 310 including the positive electrode plate 330, the negative electrode plate 320 (the outermost negative electrode plate 320G and the intermediate negative electrode plate 320T described later) and the separator 350, and the power generation element 310. It is a lithium ion secondary battery provided with the electrolyte solution 60 containing lithium ion (refer FIG. 11). In addition, the battery 301 accommodates the electric power generation element 310 in the battery case 80 similar to Embodiment 1 (refer FIG. 11).

  Among these, the power generation element 310 is a stacked power generation element in which a plurality of positive electrode plates 330 and negative electrode plates 320 are alternately stacked via separators 350 (see FIG. 12). In the power generation element 310, the positive electrode plate 330 and the negative electrode plate 320 are configured such that the outermost negative electrode plate 320G is disposed on the outermost side in both the stacking directions DL (left and right directions in FIG. 12). It has become. For this reason, any positive electrode plate 330 is the negative electrode plate 320 (the outermost negative electrode plate 320G or the intermediate negative electrode plate positioned between the two outermost negative electrode plates 320G of the negative electrode plates 320). 320T). Accordingly, the positive electrode active material layers 331 on both surfaces of the positive electrode plate 330 are opposed to the negative electrode active material layer 321 of the negative electrode plate 320.

The positive electrode plate 330 has a rectangular plate-like aluminum aluminum foil 338 and two positive electrode active material layers 331 and 331 disposed on both surfaces of the aluminum foil 338, respectively.
This positive electrode active material layer 331 includes positive electrode active material particles, a conductive material, and a binder, which are not shown, as in the first embodiment.

On the other hand, the negative electrode plate 320 has a rectangular plate-like copper copper foil 328 and two negative electrode active material layers 321 and 321 respectively disposed on both surfaces of the copper foil 328. Among the negative electrode plates 320, the negative electrode active material layer 321 in the outermost negative electrode plate 320G that is located outside the copper foil 328 in the stacking direction DL is referred to as the outermost negative electrode active material layer 321G.
Among these, the negative electrode active material layer 321 (including the outermost negative electrode active material layer 321G) includes negative electrode active material particles and a binder as in the negative electrode active material layer 21 of the first embodiment.
As shown in FIG. 12, the outermost negative electrode active material layer 321 </ b> G of the outermost negative electrode plate 320 </ b> G is disposed not facing the positive electrode plate 330 and facing the outside of the power generation element 310.

  Moreover, in the second embodiment, the entire outermost negative electrode active material layer 321G is subjected to a permeation preventing process for preventing the electrolyte solution 60 from penetrating. Specifically, as in the first embodiment, a treatment in which polytetrafluoroethylene is dispersed in a solvent is applied to the outermost negative electrode active material layer 321G and heat-dried. By this permeation prevention treatment, a polytetrafluoroethylene film is formed on the surface of the outermost negative electrode active material layer 321G. This prevents the electrolytic solution 60 from penetrating into the outermost negative electrode active material layer 321G. For this reason, lithium ions can be prevented from entering the outermost negative electrode active material layer 321G through the electrolytic solution 60.

  In the battery 301 according to the second embodiment, the multilayer power generation element 310 is provided, and the outermost negative electrode active material layer 321G of the outermost negative electrode plate 320G is subjected to permeation prevention treatment. 60 does not penetrate. Therefore, it is possible to prevent lithium ions from entering the outermost negative electrode active material layer 321G through the electrolytic solution 60 and remaining occluded in the outermost negative electrode active material layer 321G. Thus, a battery 301 in which a decrease in battery capacity is suppressed can be obtained.

Next, a method for manufacturing the battery 301 according to the second embodiment will be described.
First, the negative electrode plate 320 is produced. Specifically, as in the first embodiment, the paste (not shown) obtained by adding and kneading the negative electrode active material particles into NMP in which the binder is dissolved is applied to both sides of the rectangular copper foil 328. It was applied and dried. Thereafter, the dried paste was compressed by a roll press (not shown) to produce a negative electrode plate having a densified negative electrode active material layer 321.
Next, with respect to the negative electrode plate to be used for the outermost negative electrode plate 320G, a dispersion liquid (not shown) in which polytetrafluoroethylene is dispersed in a solvent is applied to the entire surface of the negative electrode active material layer 321 on one side, followed by heat drying. I let you. Thereby, the outermost negative electrode plate 320G subjected to the permeation prevention treatment was produced. The negative electrode plate that has not been subjected to the permeation prevention treatment is used as the intermediate negative electrode plate 320T.

On the other hand, paste (not shown) obtained by charging and kneading the cathode active material particles made of LiCoO ₂ and the conductive material into NMP in which the binder is dissolved is applied to both sides of the aluminum foil 338 having a rectangular plate shape. And dried. Then, the positive electrode plate 330 which compressed the dried paste with the roll press which is not shown in figure was produced.

The power generation element 110 is formed by stacking the separator 120 between the positive electrode plate 330 and the negative electrode plate 320 manufactured as described above.
Specifically, first, the positive electrode plate 330, the separator 350, the intermediate negative electrode plate 320T, and the separator 350 are repeatedly laminated in this order.
Next, the outermost negative electrode plate 320G is disposed and stacked on the outer side of the positive electrode plate 330 positioned on the outermost side in the stacking direction DL via the separator 350. At this time, the outermost negative electrode active material layer 321G of the outermost negative electrode plate 320G is not opposed to the positive electrode plate 330 and is disposed outside the copper foil 328 in the stacking direction DL. Further, the separators 350 are arranged and stacked on the outer side of the outermost negative electrode plate 320G in the stacking direction DL, and the stacked power generation element 310 is completed.

  Thereafter, the positive electrode current collecting member 91 or the negative electrode current collecting member 92 is welded to the positive electrode plate 330 (aluminum foil 338) and the negative electrode plate 320 (copper foil 328), respectively, inserted into the battery case body 81, and the above-described electrolysis is performed. After injecting the liquid 60, the battery case body 81 is sealed with a sealing lid 82 by welding. Thus, the battery 301 is completed (see FIG. 11).

(Embodiment 3)
A vehicle 400 according to the third embodiment includes a battery pack 410 including a plurality of the above-described batteries 1, 101, 201, and 301. Specifically, as shown in FIG. 13, vehicle 400 is a hybrid vehicle that is driven by using engine 440, front motor 420, and rear motor 430 together. The vehicle 400 includes a vehicle body 490, an engine 440, a front motor 420, a rear motor 430, a cable 450, an inverter 460, and a battery pack 410 having a rectangular box shape. Among these, the battery pack 410 contains a plurality of the batteries 1, 101, 201, 301 described above.

  Since the vehicle 400 according to the third embodiment is equipped with the batteries 1, 101, 201, and 301 in which the decrease in battery capacity is suppressed, the vehicle 400 having a power source with stable performance can be obtained.

(Embodiment 4)
Further, the hammer drill 500 of the fourth embodiment is mounted with the battery pack 510 including the batteries 1, 101, 201, and 301 described above, and as shown in FIG. 14, the battery having the battery pack 510 and the main body 520. On-board equipment. Battery pack 510 is housed in bottom 521 of main body 520 of hammer drill 500.

  Since the hammer drill 500 according to the fourth embodiment is equipped with the batteries 1, 101, 201, 301 in which the decrease in battery capacity is suppressed, it can be a battery-equipped device having a drive energy source with stable performance. .

In the above, the present invention has been described with reference to the first to fourth embodiments and the first and second embodiments. However, the present invention is not limited to the above-described embodiments, and may be appropriately changed without departing from the gist thereof. Needless to say, this is applicable.
For example, in Embodiment 1 or the like, as the permeation prevention treatment, for example, a treatment in which a coating material made of polytetrafluoroethylene is dispersed in a solvent is applied to the outward portion and dried. However, for example, a film-like coating material is attached to the outward portion and then heated and welded, the coating material is rubbed against the outward portion, a powdery coating material is sprayed on the outward portion, and then heated and welded. Processing may be performed.
Further, although the fluororesin polytetrafluoroethylene is used as the coating material, for example, the above-described organic polymer material or liquid repellent material may be used in addition to the other fluororesin.

  Moreover, although the deformation | transformation form showed the form which performed the permeation | blocking prevention process to the whole inner non-opposing part of the inner side negative electrode active material layer, the part of the inner non-opposing part (for example, the periphery of an inner non-opposing part) An anti-penetration treatment may be applied to. Further, in the second modification, a form in which the perimeter of the outermost outwardly facing portion of the outer negative electrode active material layer is subjected to permeation prevention treatment is shown, but the present invention is not limited to this, and permeates at least a part of the outermost outwardly facing part. What is necessary is just to perform the prevention process. In Embodiment 2, the entire outermost negative electrode active material layer has been subjected to permeation prevention treatment. However, a part of the outermost negative electrode active material layer (for example, the periphery of the outermost negative electrode active material layer). An anti-penetration treatment may be applied to.

1,101,201,301 battery (lithium ion secondary battery)
10, 110, 210 Power generation element (winding power generation element)
20, 120, 220, 320 Negative electrode plate 21, 221 Outside negative electrode active material layer (negative electrode active material layer)
21B, 221B Outermost outermost part (outward part)
25,125 Inner negative electrode active material layer (negative electrode active material layer)
25B, 125B Inner non-facing portion 28, 328 Copper foil (negative electrode current collector plate)
28X outer side surface 28Y inner side surface 30,330 positive electrode plate 31 outer side positive electrode active material layer (positive electrode active material layer)
35 Inner positive electrode active material layer (positive electrode active material layer)
38,338 Aluminum foil (positive current collector)
38X Outer side surface 38Y Inner side surface 50,350 Separator 60 Electrolyte 310 Power generation element (stacked power generation element)
320G Outermost negative electrode plate 321 Negative electrode active material layer 321G Outermost negative electrode active material layer (outward portion)
331 Positive electrode active material layer 400 Vehicle 500 Hammer drill (battery mounted device)
AX Winding axis DA Longitudinal direction DL Laminating direction

Claims (8)

Positive electrode current collector plate, positive electrode plate including positive electrode active material layer disposed on both surfaces of this positive electrode current collector plate, negative electrode current collector plate, and negative electrode active material disposed on both surfaces of this negative electrode current collector plate A power generation element having a negative electrode plate including a layer and a separator, and the separator interposed between the positive electrode plate and the negative electrode plate, and
An electrolyte solution that is held by the power generation element and contains lithium ions,
Any portion of the positive electrode active material layer is a lithium ion secondary battery facing the negative electrode active material layer,
Among the negative electrode active material layers, at least a part of the outward portion facing the outside of the power generation element not facing the positive electrode plate is subjected to a permeation prevention treatment for preventing permeation of the electrolytic solution. Next battery. The lithium ion secondary battery according to claim 1,
The power generation element is:
Each of the wound-type power generation elements has a belt-like positive electrode plate, the negative electrode plate, and the separator, and the positive electrode plate, the negative electrode plate, and the separator are wound around a winding axis. And
The positive electrode plate is
The positive electrode active material layer, including an inner positive electrode active material layer disposed on an inner surface of the positive electrode current collector plate, and an outer positive electrode active material layer disposed on an outer surface;
The negative electrode plate is
The negative electrode active material layer, including an inner negative electrode active material layer disposed on an inner surface of the negative electrode current collector plate, and an outer negative electrode active material layer disposed on an outer surface;
The outer cathode active material layer faces the inner anode active material layer;
The outward portion is
The lithium ion secondary battery which is an outermost outer periphery outward part located in the outermost periphery among the said outer side negative electrode active material layers. The lithium ion secondary battery according to claim 2,
The inner negative electrode active material layer is
An inner non-opposing portion where the outer positive electrode active material layer facing through the separator is not present at the winding end portion thereof,
A lithium ion secondary battery in which the permeation prevention treatment is applied to at least a part of the inner non-facing portion. The lithium ion secondary battery according to claim 1,
The power generation element is:
A laminated power generation element formed by alternately laminating the positive electrode plate and the negative electrode plate while interposing the separator,
The outward portion is
Among the negative electrode plates, in the outermost negative electrode plate disposed on the outermost side in the stacking direction, a lithium ion secondary battery that is the outermost negative electrode active material layer positioned on the outer side in the stacking direction than the negative electrode current collector plate . The lithium ion secondary battery according to any one of claims 1 to 4,
The lithium ion secondary battery by which the said permeation prevention process is given to the periphery of the said outward part. The lithium ion secondary battery according to any one of claims 1 to 4,
The lithium ion secondary battery by which the said penetration prevention process is given to the said whole outward part. A vehicle on which the lithium ion secondary battery according to any one of claims 1 to 6 is mounted and the electric energy stored in the lithium ion secondary battery is used for all or part of a power source. A battery-mounted device in which the lithium ion secondary battery according to any one of claims 1 to 6 is mounted and the electric energy stored in the lithium ion secondary battery is used for all or a part of a drive energy source. .

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