JP2013084387A - Electrical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve vibration resistance of an electrical device by suppressing the occurrence of a displacement and flexure of a positive electrode or a negative electrode.SOLUTION: An electrical device is formed by laminating a positive electrode, a separator and a negative electrode, in the order. The separator includes a restriction part brought into contact with an end of the positive electrode or the negative electrode so that the movement of the positive electrode or the negative electrode in a direction vertical to the lamination direction is restricted.

Description

  The present invention relates to an electrical device, particularly an electricity storage device such as a battery.

  In a power storage device (electric device) such as a battery, stacking misalignment of the positive electrode, the negative electrode, or the separator becomes a problem. In the non-aqueous electrolyte secondary battery disclosed in Patent Document 1, the separator is provided at the end of the positive electrode or the negative electrode, and the fixing member is provided so that the ends of the plurality of separators that have risen overlap each other.

JP 2008-204706 A

  However, in the nonaqueous electrolyte secondary battery of Patent Document 1, since the end portions of the separator are fixed together, displacement or bending of the positive electrode or the negative electrode (electrode) cannot be completely prevented, and there is room for improvement.

  The present invention has been made paying attention to such a conventional problem, and an object thereof is to improve the vibration resistance of an electric device by suppressing displacement and bending of a positive electrode or a negative electrode.

  An electric device according to an aspect of the present invention is formed by stacking a positive electrode, a separator, and a negative electrode in this order. And the said separator is provided with the control part which contacts the edge part of the said positive electrode, or the edge part of the said negative electrode so that the movement of the said positive electrode or the said negative electrode of the direction perpendicular | vertical to a lamination direction may be controlled.

  ADVANTAGE OF THE INVENTION According to this invention, the vibration resistance of an electric device can be improved by suppressing the gap | deviation and bending of a positive electrode or a negative electrode.

(A) It is sectional drawing perpendicular | vertical to the lamination direction of the nonaqueous electrolyte secondary battery (electrical device) which concerns on 1st embodiment. (B) It is sectional drawing of the lamination direction of the nonaqueous electrolyte secondary battery (electrical device) which concerns on 1st embodiment (cross section along Ib-Ib of FIG. 1). It is sectional drawing along the lamination direction of the laminated body which concerns on 1st embodiment. (A) It is a perspective view of the separator which concerns on 1st embodiment. (B) It is sectional drawing of the separator which concerns on 1st embodiment (cross section along IIIb-IIIb of Fig.3 (a)). It is a perspective view of the separator which concerns on 2nd embodiment. It is a perspective view which shows the other form of the separator which concerns on 2nd embodiment. It is a partial cross section figure of the laminated body which concerns on 3rd embodiment. It is a partial cross section figure of the laminated body which concerns on 4th embodiment. It is a partial cross section figure of the laminated body which concerns on 5th embodiment. It is a partial cross section figure of the laminated body which concerns on 6th embodiment. (A) It is a perspective view of the separator which shows the welding part which concerns on 6th embodiment. (B) It is a perspective view of the separator which shows the other welding part which concerns on 6th embodiment. It is a perspective view of the modification of a separator.

  Hereinafter, embodiments for carrying out the present invention will be described in more detail with reference to the drawings.

[First embodiment]
FIGS. 1A and 1B are cross-sectional views showing the configuration of the nonaqueous electrolyte secondary battery 1 according to the first embodiment. In the present embodiment, the nonaqueous electrolyte secondary battery 1 is shown as an example of an electric device (storage electric device). Moreover, in 1st embodiment, although the nonaqueous electrolyte secondary battery 1 is a lithium ion battery, it is not limited to this. FIG. 1A is a cross-sectional view perpendicular to the stacking direction of the stacked body 2. FIG. 1B is a cross-sectional view along the stacking direction of the stacked body 2. The nonaqueous electrolyte secondary battery 1 is encapsulated by a laminate 2 and an aluminum laminate film 3 that encloses the laminate 2. The laminate 2 is a power generation element that generates power, and is immersed in the electrolytic solution 7 in the aluminum laminate film 3. The positive electrode 4 of the multilayer body 2 is connected to the electrode tab 8a, and the negative electrode 6 of the multilayer body 2 is connected to the electrode tab 8b.

  FIG. 2 is a cross-sectional view along the stacking direction of the stacked body 2. In the laminate 2 (power generation element), the positive electrode 4, the separator 5, and the negative electrode 6 are laminated in this order. Below, the manufacturing method of the laminated body 2 is shown concretely.

The positive electrode 4 is produced by applying a positive electrode slurry in which a positive electrode active material, a conductive additive and a binder are mixed in a predetermined ratio to the positive electrode current collector foil 4a and drying it. In the present embodiment, the positive electrode current collector foil 4a is an aluminum foil having a thickness of about 20 μm, but other materials can also be used. In the present embodiment, the positive electrode active material is lithium manganate (LiMn ₂ O ₄ ). Note that the positive electrode active material may be lithium nickel oxide (LiNiO ₂ ) or other lithium composite oxide such as lithium cobalt oxide (LiCoO ₂ ). The conductive auxiliary agent is, for example, acetylene black. The binder is, for example, polyvinylidene fluoride (PVdF).

Specifically, the positive electrode slurry is prepared by dissolving a mixture of 85 wt% LiMn ₂ O ₄ , 5 wt% acetylene black, and 10 wt% PVdF in a slurry viscosity adjusting solvent (N-methylpyrrolidone (NMP)). It is a thing. The positive electrode slurry was prepared by dissolving a mixture of 92% by weight of LiMn ₂ O ₄ , 5% by weight of acetylene black and 3% by weight of styrene butadiene rubber in a slurry viscosity adjusting solvent (N-methylpyrrolidone (NMP)). It may be a thing. The positive electrode slurry is applied to both surfaces of the positive electrode current collector foil 4a, dried and then formed into the positive electrode active material layer 4b. The positive electrode 4 is formed by pressing so that the thickness of the positive electrode active material layer 4b is 60 μm on one side of the positive electrode current collector foil 4a.

  The separator 5 is formed of a microporous polyethylene film including a large number of minute holes. The separator 5 is formed in a plate shape so as to have a thickness of 15 μm. Thereafter, as will be described later, the central portion of the separator 5 is pressed.

  The negative electrode 6 is produced by applying a negative electrode slurry in which a negative electrode active material and a binder are mixed at a predetermined ratio to the negative electrode current collector foil 6a and drying it. In the present embodiment, the negative electrode current collector foil 6a is a copper foil having a thickness of about 20 μm, but other materials can also be used. The negative electrode active material is a carbon material such as hard carbon. The binder is, for example, polyvinylidene fluoride (PVdF).

  Specifically, the negative electrode slurry is obtained by dissolving a mixture of 90% by weight of hard carbon and 10% by weight of PVdF in a slurry viscosity adjusting solvent (N-methylpyrrolidone (NMP)). The negative electrode slurry is applied to both surfaces of the negative electrode current collector foil 6a, and is formed after drying to form the negative electrode active material layer 6b. The negative electrode is formed by pressing so that the thickness of the negative electrode active material layer 6b is 60 μm on one side of the negative electrode current collector foil 6a.

  The electrolyte solution (liquid electrolyte) 7 is an organic one as a nonaqueous electrolyte. The electrolytic solution 7 is obtained by dissolving lithium hexafluorophosphate (LiPF6) as a solute in an organic solvent at a concentration of 1 mol / L. The organic solvent is a liquid mixture in which ethylene carbonate (EC) and diethylene carbonate (DEC) are mixed at a mixing ratio of 1: 1 by volume.

  The positive electrode 4, the separator 5, and the negative electrode 6 produced as described above are cut and then laminated to produce a laminate 2. The laminate 2 is enclosed in an aluminum laminate film 3. In the aluminum laminate film 3, a part facing one side of the laminate 2 is opened, and the electrolyte solution 7 is injected from one side. Thereafter, the inside of the aluminum laminate film 3 is evacuated and sealed.

  The configuration of the separator 5 that is a feature of the present embodiment will be described.

  3A and 3B show the detailed configuration of the separator 5 of the present invention. Concave portions 51 are formed on both surfaces in the stacking direction in the central portion of the separator 5. The separator 5 having the concave portion 51 is formed by pressing both surfaces of a flat plate-like (square shape) separator member. The concave portion 51 includes a flat plate portion (bottom surface of the concave portion) 5a of the separator 5 perpendicular to the stacking direction, and a wall portion 5b of the separator 5 extending from the flat plate portion 5a in the stacking direction (that is, a direction perpendicular to the flat plate portion 5a). The An electrode is placed on the main surface of the flat plate portion 5a of the separator 5, and the recess 51 accommodates the electrode (that is, the positive electrode 4 or the negative electrode 6). The wall 5b of the separator 5 functions as a restricting portion 30 that contacts the end of the electrode so as to restrict the movement of the electrode in the direction perpendicular to the stacking direction of the stacked body 2.

  The separator 5 is in contact with the adjacent separator at the wall 5b. The separator 5 is welded to an adjacent separator at the outermost peripheral portion 9 that is the outermost portion in the direction perpendicular to the stacking direction. The electrode and the separator 5 are laminated in such a manner that the separator 5 accommodates the electrode, thereby constituting the laminate 2.

-Effect-
As described above, according to this embodiment, it is possible to suppress the displacement and bending of the electrode that is the positive electrode 4 or the negative electrode 6 at low cost, and it is possible to improve the vibration resistance and avoid the deterioration of the battery performance. This is because the separator 5 includes a regulating portion 30 that contacts the end of the electrode so as to regulate the movement of the electrode (that is, the positive electrode 4 or the negative electrode 6) in the direction perpendicular to the stacking direction. For this reason, the electrode can be easily positioned with respect to the separator 5. Furthermore, the edge part (edge part) of an electrode will be protected by the separator 5, and deterioration of an electrode or the separator 5 can be suppressed. Furthermore, since it is not necessary to provide a welding allowance in the separator, the electrode can be enlarged and the battery capacity is improved.

  The restricting portion 30 includes a flat plate portion 5a of the separator 5 on which an electrode (that is, the positive electrode 4 or the negative electrode 6) is placed, and a wall portion 5b extending from the flat plate portion 5a in the stacking direction. For this reason, it is possible to easily position the electrode with respect to the separator 5 at a lower cost, and the displacement and bending of the electrode can be strongly suppressed.

  The separator 5 includes a concave portion 51 that accommodates an electrode (that is, the positive electrode 4 or the negative electrode 6), and the restricting portion 30 is a wall portion 5 b that constitutes the concave portion 51. By fitting and fixing the electrode in the recess 51, the electrode can be easily positioned with respect to the separator 5 at a lower cost, and the displacement and bending of the electrode can be strongly suppressed, and the edge portion of the electrode can be suitably protected.

  The separator 5 is welded to the adjacent separator at the outermost periphery. For this reason, vibration resistance can be further improved.

[Second Embodiment]
4 and 5 show a separator 5 according to the second embodiment. An open channel 5 c including an opening through which the electrolytic solution 7 can pass is formed on the peripheral edge of the separator 5. When the electrode (that is, the positive electrode 4 or the negative electrode 6) is placed on the separator 5, the open flow path 5c faces the end of the electrode. Other configurations are the same as those in the first embodiment, and a description thereof will be omitted.

  The separator 5 having the open flow path 5c of FIG. 4 can be formed by partially cutting the wall portion 5b of the separator 5 of the first embodiment (FIG. 3A). Further, the separator 5 having the open flow path 5c of FIG. 5 can be formed only from a flat plate-shaped separator member by pressing. Note that the separator 5 in FIG. 4 may be formed by partially cutting the four edge portions of the separator 5 in FIG. 5. 4 and 5, the wall 5b of the separator 5 is provided at the four corners of the flat plate portion 5a due to the presence of the opening.

  The porosity of the wall portion 5b of the separator 5 may be smaller than that of the separator center portion 12. In order to do so, the wall portion 5b is formed by pressing a separator member having a lower porosity than the central portion at the peripheral portion.

  According to the second embodiment, the separator 5 includes an open flow path 5c through which the electrolyte solution 7 passes at the peripheral edge. As a result, when the electrolyte solution 7 is injected, the electrolyte solution 7 can be reliably supplied to the electrode, so that the penetration can be improved, and a reduction in the charge / discharge capacity of the battery (electric device) can be avoided. Become.

  When the regulation part 30 is made by press molding the central part of the plate-shaped separator member having a constant porosity, the porosity around the electrode becomes relatively large, and the electrolyte 7 is around the electrode. There arises a problem of uneven distribution in the separator portion. However, when the porosity of the wall portion 5b of the separator 5 is made smaller than the central portion of the separator, the electrolyte solution 7 is not unevenly distributed, so that the electrolyte solution 7 can be reliably supplied to the electrode, and a decrease in charge / discharge capacity can be avoided. It becomes possible.

[Third embodiment]
FIG. 6 shows a separator 5 according to the third embodiment. In the separator 5, the peripheral edge portion (end portion) is bent at a position facing the end portions of the four sides of the electrode (that is, the positive electrode 4 or the negative electrode 6), and the first wall portion 5 d and the second wall portion 5 e are formed. Yes. The first wall 5d protrudes on one side in the stacking direction, and the second wall 5e protrudes on the side opposite to the first wall 5d. The second wall portion 5e is positioned outside the first wall portion 5d in the stacked body 2. Other configurations are the same as those in the first embodiment, and a description thereof will be omitted.

  The first wall portion 5d and the second wall portion 5e function as the restricting portion 30. The first wall portion 5 d of the separator 5 is in contact with the end portion of the positive electrode 4 (shorter electrode) and restricts the movement of the positive electrode 4 in the direction perpendicular to the stacking direction of the stacked body 2. The second wall 5 e of the separator 5 abuts on the end of the negative electrode 6 (longer electrode) and restricts the movement of the negative electrode 6 in the direction perpendicular to the stacking direction of the stacked body 2.

  Since the first wall portion 5d and the second wall portion 5e are provided at different positions in the direction along the flat plate portion 5a of the separator 5, the third embodiment differs from the other embodiments in that the positive electrode 4 and the negative electrode It is preferable to apply only when the length of 6 is different. For example, in a lithium ion secondary battery, in order to prevent precipitation of lithium ions, the negative electrode 6 is longer than the positive electrode 4, and the area of the negative electrode 6 is larger than the area of the positive electrode 4.

  According to the third embodiment, the restricting portion 30 includes a peripheral edge portion of the separator 5 that is bent at a position facing the end portion of the electrode. When the regulating part 30 is made by press molding the central part of the plate-shaped separator member having a constant porosity, the porosity around the electrode becomes relatively large, and the electrolyte 7 is around the electrode. There arises a problem that the separator portion is unevenly distributed and accumulates. However, in the third embodiment, since the regulating portion 30 is formed by bending the plate-shaped separator member, the porosity of the separator 5 as a whole is constant, and the electrolyte 7 is not unevenly distributed and is reliably electrolyzed to the electrode. Liquid 7 can be supplied. Thereby, the penetration of the electrolytic solution 7 into the electrode can be improved, and the decrease in the charge / discharge capacity can be avoided.

[Fourth embodiment]
FIG. 7 shows a separator 5 according to the fourth embodiment. The separator 5 includes a plate-shaped flat plate portion 5a and a wall portion 5f made of a separator member laminated on the flat plate portion 5a around the electrode (that is, the positive electrode 4 or the negative electrode 6). The wall 5f serves as a restricting portion 30 that contacts the end of the electrode so as to restrict the movement of the electrode in the direction perpendicular to the stacking direction of the stacked body 2. The separator member to be the flat plate portion 5a and the separator member to be the wall portion 5f are connected by welding at the outermost peripheral portion. Other configurations are the same as those in the first embodiment, and a description thereof will be omitted.

  In FIG. 7, the wall 5f is made of a single separator member, but the wall 5f may be made up of a plurality of laminated separator members. In FIG. 7, the length and area of the positive electrode 4 and the negative electrode 6 are different but may be the same.

  According to the fourth embodiment, the restricting portion 30 is a separator member stacked around the electrode. When the regulating part 30 is made by press molding the central part of the plate-shaped separator member having a constant porosity, the porosity around the electrode becomes relatively large, and the electrolyte 7 is around the electrode. There arises a problem that the separator portion is unevenly distributed and accumulates. However, in 4th embodiment, since the control part 30 is the member for separators laminated | stacked around the electrode, the porosity becomes constant in the separator 5 whole, and the electrolyte solution 7 can be reliably supplied to an electrode. Thereby, the penetration of the electrolytic solution 7 into the electrode can be improved, and the decrease in the charge / discharge capacity can be avoided.

[Fifth embodiment]
FIG. 8 shows a separator 5 according to the fifth embodiment. The peripheral portion of the electrode (that is, the positive electrode 4 or the negative electrode 6) is covered with the wall portions of the plurality of separators 5. The wall 5g of a certain separator 5 ′ (first type separator) overlaps the wall 5h of the adjacent separator 5 ″ (second type separator) in the direction perpendicular to the stacking direction around the electrodes. However, the lengths and areas of the positive electrode 4 and the negative electrode 6 are different, but may be the same, and the other configurations are the same as those of the first embodiment, and the description thereof is omitted.

  The first type of separator 5 ′ includes one wall portion 5 g that contacts the end portion of the electrode and functions as the restricting portion 30. On the other hand, the second type separator 5 ″ includes two wall portions 5h and 5i having different heights. The inner wall portion 5i contacts the end portion of the electrode and functions as the regulating portion 30. The outer wall portion. 5h covers the wall 5g of the first type separator 5 'from the outside.

  The height (thickness) of the inner wall 5i in the stacking direction is smaller than the height (thickness) of the outer wall 5h in the stacking direction. The inner wall portion 5i and the outer wall portion 5h are provided in a stepwise manner. The wall portion 5g of the first type separator 5 ′ is in contact with the inner wall portion 5i of the second type separator 5 ″ in the stacking direction. The wall portion 5g of the first type separator 5 ′ is the second type separator. 5 ′ outside wall 5h is in contact with and overlapped in the direction perpendicular to the stacking direction.

  According to the fifth embodiment, a wall of a separator overlaps with a wall of an adjacent separator in a direction perpendicular to the stacking direction around the electrodes. Therefore, when an electrode (especially negative electrode 6) expand | swells by progress of a charging / discharging cycle, it can prevent that the edge part of an electrode remove | deviates from the separator which supports an electrode.

[Sixth embodiment]
FIG. 9 shows a separator 5 according to the sixth embodiment. In the outermost peripheral portion of the separator 5, the positions are shifted in the stacking direction with respect to the facing surfaces of the stacked body 2, and welding is performed alternately in a zigzag manner. As shown in FIGS. 10A and 10B, the separator 5 is welded to the adjacent separator 5-1 on the upper side in the welded portion 9a at one end, and is adjacent to the lower side in the welded portion 9b on the other end. -2 to be welded. Note that the terms “upper side” and “lower side” express the direction for convenience, and may be replaced by, for example, “right side” and “left side”, respectively. In FIG. 9, the length and area of the positive electrode 4 and the negative electrode 6 are different but may be the same. Other configurations are the same as those of the second embodiment, and a description thereof will be omitted.

  According to the sixth embodiment, the separator 5 is welded at one end to the adjacent separator on the upper side in the stacking direction and is welded at the other end to the adjacent separator on the lower side in the stacking direction. Accordingly, the gap between the opposing wall portions of the adjacent separators is closed by welding on one end side of the electrode (that is, the positive electrode 4 or the negative electrode 6), but is open on the other end side of the electrode. Therefore, the electrolyte solution 7 easily enters the electrode from the gap on the other end side. Moreover, when an electrode (especially negative electrode 6) expand | swells by charging / discharging cycle progress, the separator 5 can follow expansion | swelling of an electrode and it can suppress the shift | offset | difference and bending of an electrode.

  Without being limited to the embodiments described above, various modifications and changes are possible within the scope of the technical idea, and it is obvious that these are also included in the technical scope of the present invention.

  For example, the restriction part 30 may be a wall part provided on four sides (not on the four corners) of the flat plate part 5a as shown in FIG. Moreover, as another electric device to which the present invention can be applied, a primary battery or a secondary battery other than a lithium ion battery may be used. Furthermore, the present invention can be applied to a capacitor other than a battery as long as it is an electric device configured by laminating a positive electrode, a negative electrode, and a separator.

1 Nonaqueous electrolyte secondary battery (electrical device)
2 Laminate 3 Aluminum Laminated Film 4 Positive Electrode 5 Separator 5 'First Type Separator 5 "Second Type Separator 5a Flat Plate Part 5b, 5f, 5g Wall Part 5c Open Channel 5d First Wall Part 5e Second Wall Part 5h Outer wall portion 5i Inner wall portion 6 Negative electrode 7 Electrolytic solution 30 Restriction portion 51 Recess

Claims (10)

An electrical device formed by laminating a positive electrode, a separator, and a negative electrode in this order,
The electrical device, wherein the separator includes a restricting portion that contacts an end portion of the positive electrode or the negative electrode so as to restrict movement of the positive electrode or the negative electrode in a direction perpendicular to the stacking direction. The separator includes a recess that accommodates the positive electrode or the negative electrode,
The electric device according to claim 1, wherein the restricting portion is a wall portion constituting the concave portion.   The electric device according to claim 2, wherein the separator includes an open channel through which an electrolyte solution passes at a peripheral edge portion thereof.   The electric device according to claim 1, wherein the restricting portion includes a peripheral portion of the separator bent at a position facing an end portion of the positive electrode or the negative electrode.   The electric device according to claim 1, wherein the restricting portion is a separator member that is stacked around the positive electrode or the negative electrode. The regulation part is
A flat plate portion of the separator on which the positive electrode or the negative electrode is placed;
The electric device according to claim 1, further comprising a wall portion extending in the stacking direction from the flat plate portion.   The electric device according to claim 6, wherein the wall portion of the separator overlaps the wall portion of an adjacent separator in a direction perpendicular to the stacking direction around the positive electrode or the negative electrode.   The electrical device according to claim 1, wherein the separator is welded to an adjacent separator at an outermost peripheral portion.   The electrical device according to claim 1, wherein the separator is welded to an adjacent separator on the upper side in the stacking direction at one end and welded to an adjacent separator on the lower side in the stacking direction at the other end.   The electrical device according to claim 1, wherein a porosity of an end portion of the separator located around the positive electrode or the negative electrode is smaller than a central portion of the separator.

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