JP2017063005A - Method for manufacturing assembled battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of manufacturing an assembled battery in which capacity reduction is unlikely to occur. A battery assembly manufacturing method disclosed herein includes a preparing step of preparing a plurality of unit cells each including an electrode body, an electrolyte, and a battery case, and a first convex portion and a first concave portion. A first restraining step of alternately arranging the first cooling insulating plate having the controlled first cooling path and the unit cells in a predetermined direction and restraining them, and performing an aging treatment after the restrained unit cells are initially charged. The aging step, the second cooling insulating plate having the second cooling path formed by the second convex portion and the second concave portion, and the unit cell are alternately arranged in a predetermined direction and restrained. And a restraining step. At the position where the second convex portion of the second cooling insulating plate contacts the battery case of the single cell in the second restraining step, the first convex portion of the first cooling insulating plate is the single convex portion in the first restraining step. The position where the battery contacts the battery case is different without overlapping. [Selection diagram] Figure 1

Description

  The present invention relates to a method for manufacturing an assembled battery in which a plurality of chargeable / dischargeable cells (secondary batteries) are arranged in a predetermined direction and restrained in a state where a load is applied in the arrangement direction.

  Lithium-ion secondary batteries, nickel-metal hydride batteries, other secondary batteries or capacitors and other storage elements are used as unit cells. Importance is increasing as a power source or a power source for personal computers and portable terminals. In particular, an assembled battery formed by connecting a plurality of lithium ion secondary batteries that are lightweight and have a high energy density as a single battery is preferably used as a high-output power source for mounting on a vehicle.

  As one of the configurations of a general assembled battery, a single cell and a cooling insulating plate provided with a cooling path by a convex portion and a concave portion are alternately arranged in a predetermined direction, and a load is applied in the arrangement direction. The structure restrained by the state is mentioned (for example, refer patent documents 1-3).

JP 2008-108651 A JP 2009-048965 A JP 2009-259455 A

  In the assembled battery, the unit cells are constrained in a state where a load is applied in the arrangement direction, whereby pressure is also applied to the electrode body housed in the battery case of the unit cells. Here, since the cooling insulating plate is formed with the convex portion and the concave portion, there is a difference in the applied pressure between the portion facing the convex portion and the portion facing the concave portion of the electrode body. According to the study by the present inventors, the distance between the positive electrode and the negative electrode of the electrode body (the distance between the positive electrode and the negative electrode of the electrode body) due to the pressure difference between the portion facing the convex portion and the portion facing the concave portion in the electrode body. It was found that a distribution occurred in the distance between the electrodes). In such a state in which the inter-electrode distance is distributed, metallic lithium is likely to be deposited at the boundary portion between the portion facing the convex portion and the portion facing the concave portion of the electrode body. As a result, the battery It was newly found that the capacity tends to decrease. That is, the present inventors have newly found that there is room for improvement in battery capacity reduction in an assembled battery.

  The present invention has been created in view of such circumstances, and an object of the present invention is to provide a method capable of manufacturing an assembled battery in which a decrease in capacity is unlikely to occur.

A method for manufacturing an assembled battery disclosed herein includes an electrode body in which a positive electrode sheet and a negative electrode sheet are laminated via a separator, an electrolyte, and a battery case that houses the electrode body and the electrolyte. A preparatory step for preparing a unit cell, a first cooling insulating plate having a first cooling path formed by a first projection and a first recess, and the unit cell are alternately arranged in a predetermined direction. And a first constraining step of constraining the load in the arrangement direction, an aging step of performing an aging process after initially charging the constrained unit cell, and a second convex portion and a second concave portion. A second restraining step of alternately arranging the second cooling insulating plates having the formed second cooling paths and the unit cells in a predetermined direction and restraining the load in the arrangement direction. Including. In the manufacturing method, the position at which the second convex portion of the second cooling insulating plate is in contact with the battery case of the unit cell in the second restraining step is the first restraining step. The first protrusion of the cooling insulating plate is different from the position in contact with the battery case of the unit cell without overlapping.
According to such a configuration, the distribution of the distance between the electrodes in the electrode body generated by the aging process is different from the distribution of the distance between the electrodes in the electrode body generated by the construction of the assembled battery. Distance distribution can be canceled. As a result, in the obtained assembled battery, the distribution of the interelectrode distance in the electrode body can be narrowed. Thereby, it becomes difficult to deposit metallic lithium. Therefore, it is possible to manufacture an assembled battery in which the capacity is hardly reduced.

  In this specification, the “unit cell” is a term indicating individual storage elements that can be connected in series to form an assembled battery, and includes batteries and capacitors having various compositions unless otherwise specified. . The “secondary battery” generally refers to a battery that can be repeatedly charged, and includes so-called storage batteries such as lithium ion secondary batteries and nickel metal hydride batteries.

It is a flowchart which shows the outline of the manufacturing method of the assembled battery which concerns on this embodiment. It is the schematic of the lithium ion secondary battery which is a single battery used for the manufacturing method of the assembled battery which concerns on this embodiment. It is a schematic diagram of the surface in which the cooling path of the 1st cooling insulation plate used in the 1st restraint process of the manufacturing method of the assembled battery which concerns on this embodiment was formed. It is AA sectional drawing of FIG. It is a perspective view which shows typically the arrangement | sequence and restraint state of a 1st cooling insulation plate and a cell in the 1st restraint process of the manufacturing method of the assembled battery which concerns on this embodiment. It is a schematic cross section of a part of the 1st cooling insulation plate and unit cell which were arranged in the 1st restraint process. It is a schematic diagram of the surface in which the cooling path of the 2nd cooling insulation plate used at the 2nd restraint process of the manufacturing method of the assembled battery which concerns on this embodiment was formed. It is BB sectional drawing of FIG. It is a perspective view which shows typically the arrangement | sequence and restraint state of a 2nd cooling insulation plate and a cell in the 2nd restraint process of the manufacturing method of the assembled battery which concerns on this embodiment. It is a schematic cross section of a part of 2nd cooling insulation plate and unit cell arranged in the 2nd restraint process. It is a line graph which shows the distance between electrodes of the electrode body accommodated in the cell in the assembled battery according to a prior art. FIG. 12 is a diagram in which a line graph (thick line) indicating a distance between electrodes after aging processing is superimposed on the line graph (thin line) in FIG. 11. It is a line graph which shows the distance between the electrodes of the electrode body accommodated in the single battery in the assembled battery obtained by the manufacturing method which concerns on this embodiment. It is a graph which shows the fall amount of the battery capacity after the pulse cycle test of the assembled battery concerning Test Example 1 and Test Example 2.

  Embodiments according to the present invention will be described below with reference to the drawings. Note that matters other than the matters specifically mentioned in the present specification and necessary for the implementation of the present invention (for example, a general configuration and manufacturing process of an assembled battery that does not characterize the present invention) It can be grasped as a design matter of those skilled in the art based on the prior art. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field. Moreover, in the following drawings, the same code | symbol is attached | subjected and demonstrated to the member and site | part which show | plays the same effect | action. In addition, the dimensional relationships (length, width, thickness, etc.) in each drawing do not reflect actual dimensional relationships.

  The outline of the manufacturing method of the assembled battery which concerns on FIG. 1 at this embodiment is shown. A method of manufacturing an assembled battery according to the present embodiment includes a plurality of unit cells each including an electrode body in which a positive electrode sheet and a negative electrode sheet are stacked via a separator, an electrolyte, and a battery case that houses the electrode body and the electrolyte. The preparatory step S101 for preparing the first cooling insulating plate having the first cooling path formed by the first convex portion and the first concave portion, and the cells are alternately arranged in a predetermined direction, Formed by a first constraining step S102 for constraining a load in the arrangement direction, an aging step S103 for performing an aging process after initial charging of the constrained unit cells, and a second convex part and a second concave part A second restraining step S104 for alternately arranging the second cooling insulating plates having the second cooling paths and the cells in a predetermined direction and restraining the load in the arrangement direction; Include . In the manufacturing method, the position at which the second convex portion of the second cooling insulation plate contacts the battery case of the unit cell in the second restraint step S104 is the first cooling insulation plate in the first restraint step S102. The position of the first convex portion of the battery cell is different from the position where it contacts the battery case of the unit cell without overlapping.

  Examples of the single battery include a lithium ion secondary battery, a nickel metal hydride battery, a nickel cadmium battery, and an electric double layer capacitor. Hereinafter, the method for manufacturing the assembled battery according to the present embodiment will be described by taking as an example the case of using the flat rectangular lithium ion secondary battery 100 shown in FIG.

  First, the electrode body 10 in which the positive electrode sheet 12 and the negative electrode sheet 14 are laminated via the separator 16, an electrolyte (not shown), and the battery case 50 that houses the electrode body 10 and the electrolyte are provided. A preparation step S101 for preparing the single cell 100 is performed. Preparatory process S101 can be performed by producing the single battery (lithium ion secondary battery) 100 according to a well-known method.

  Specifically, for example, a long positive electrode sheet 12, a long negative electrode sheet 14, and two long separators 16 are prepared.

The positive electrode sheet 12 can be produced according to a known method. For example, the positive electrode sheet 12 is prepared by preparing a composition in which a positive electrode active material, a conductive material, a binder, and the like are mixed in an appropriate solvent, and applying the composition onto one or both surfaces of the positive electrode current collector, followed by drying. It can produce by doing. After drying, the positive electrode sheet 12 may be appropriately pressed. Examples of the positive electrode current collector include an aluminum foil. Examples of the positive electrode active material include lithium transition metal oxides (eg, LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , LiNiO ₂ , LiCoO ₂ , LiFeO ₂ , LiMn ₂ O ₄ , LiNi _0.5 Mn _{1 0.5} O ₄ ) and lithium transition metal phosphate compounds (eg, LiFePO ₄ ). As the conductive material, carbon black such as acetylene black (AB) and other (eg, graphite) carbon materials can be suitably used. As the binder, polyvinylidene fluoride (PVDF) or the like can be used.

  The negative electrode sheet 14 can be produced according to a known method. For example, the negative electrode sheet 14 is prepared by mixing a negative electrode active material and a binder in an appropriate solvent to prepare a composition, applying the composition onto one or both surfaces of the negative electrode current collector, and then drying the composition. Can be produced. After drying, the negative electrode sheet 14 may be appropriately pressed. Examples of the negative electrode current collector include copper foil. As the negative electrode active material, for example, a carbon material such as graphite, hard carbon, or soft carbon can be used. As the binder, styrene butadiene rubber (SBR) or the like can be used. As the thickener, for example, carboxymethyl cellulose (CMC) can be used.

  Examples of the separator 16 include a porous sheet (film) formed from a resin such as polyethylene (PE), polypropylene (PP), polyester, cellulose, and polyamide. Such a porous sheet may have a single-layer structure or a laminated structure of two or more layers (for example, a three-layer structure in which PP layers are laminated on both sides of a PE layer). A heat resistant layer (HRL) may be provided on the surface of the separator 16.

  The positive electrode sheet 12 and the negative electrode sheet 14 are superposed via two separators 16 to produce a laminate. At this time, the positive electrode sheet 12 is overlaid so that the positive electrode sheet 12 protrudes from one end portion in the width direction of the separator 16 and the negative electrode sheet 14 protrudes from the other end portion in the width direction of the separator 16. The electrode body 10 can be obtained by winding the produced laminated body in the longitudinal direction and crushing it from the side surface direction. Alternatively, the electrode body 10 may be manufactured by winding the laminate itself so that the winding cross section has a flat shape. Although the case where the electrode body 10 is configured as a wound electrode body is described here, the electrode body 10 may be configured as a laminated electrode body.

  Next, the electrode body 10 is accommodated in the battery case 50 according to a known method. Specifically, a main body of a flat rectangular battery case 50 having an opening and a lid of the battery case 50 having a non-aqueous electrolyte inlet are prepared. The lid has a dimension for closing the opening of the main body of the battery case 50. As a material of the battery case 50, for example, a light metal material having good thermal conductivity such as aluminum, stainless steel, or nickel-plated steel is preferably used. The positive electrode terminal 60 and the positive electrode current collector plate 60a, the negative electrode terminal 62 and the negative electrode current collector plate 62a are attached to the lid of the battery case 50. The positive electrode current collector plate 60 a and the negative electrode current collector plate 62 a are welded to the positive electrode sheet 12 and the negative electrode sheet 14 exposed at the ends of the electrode body 10, respectively. And the electrode body 10 is accommodated in the inside from the opening part of the main body of the battery case 50, and the main body and cover body of the battery case 50 are welded.

Subsequently, an electrolyte (in this case, a non-aqueous electrolyte) is injected from the injection port. As the nonaqueous electrolytic solution, typically, a nonaqueous solvent containing a supporting salt can be used. Examples of the non-aqueous solvent include carbonates. Examples of the supporting salt include lithium salts such as LiPF ₆ , LiBF ₄ , and LiClO ₄ . After injecting the non-aqueous electrolyte, the inlet is sealed to obtain a single battery (lithium ion secondary battery) 100 shown in FIG.

  A single battery (lithium ion secondary battery) 100 is prepared by the number of single batteries used as an assembled battery. The number of single cells (lithium ion secondary batteries) 100 to be prepared is two or more, and typically 3 to 35 (for example, 10 to 25), but is not limited thereto.

  Next, the unit cell (lithium ion secondary battery) 100 and the first cooling insulating plate having the first cooling path formed by the first convex portion and the first concave portion are alternately arranged in a predetermined direction. A first restraining step S102 for arranging and restraining in a state where a load is applied in the arranging direction is performed.

  3 and 4 show the first cooling insulating plate 30 used in the first restraining step S102. Here, six linear first convex portions 32 are provided, and a first concave portion 34 is formed between adjacent convex portions 32. A space on the first concave portion 34 between the adjacent convex portions 32 constitutes a first cooling path. The first cooling insulation plate 30 is preferably made of resin (eg, made of polypropylene) in order to ensure insulation.

  The single battery (lithium ion secondary battery) 100 and the first cooling insulating plate 30 are arranged as shown in FIGS. 5 and 6, for example. Specifically, the plurality of single cells 100 are arranged in a direction in which the wide surfaces of the battery case 50 face each other. At this time, the plurality of single cells 100 are arranged in a reversed manner one by one so that the positive terminals 60 and the negative terminals 62 are alternately arranged. The first cooling insulating plate 30 is disposed between the first and last portions of the row of the unit cells 100 and the adjacent unit cells 100. Between the adjacent unit cells 100, one positive electrode terminal 60 and the other negative electrode terminal 62 are electrically connected by a connector 64.

  The unit cell 100 and the first cooling insulating plate 30 arranged in this way are restrained in a state where a load is applied in the arrangement direction. For example, a restraining member that collectively restrains the plurality of single cells 100 and the first cooling insulation plate 30 is provided around the single cells 100 and the first cooling insulation plate 30. That is, the pair of restraining plates 70A and 70B are arranged on the outer side of the first cooling insulating plate 30 located on the outermost side in the arrangement direction (first and last in the row). Further, the fastening beam member 72 is attached so as to bridge the pair of restraining plates 70A and 70B. Then, by tightening and fixing the ends of the beam member 72 to the restraining plates 70A and 70B with the screws 74, the unit cells 100 can be restrained so that a predetermined load (restraining load) is applied in the arrangement direction.

What is necessary is just to select the magnitude | size of the said restraint load suitably according to the number, size, etc. of the cell 100. FIG. For example, a load is applied and restrained so that the surface pressure applied to the wide surface of the battery case 50 of the unit cell 100 is 10 ⁴ Pa to 10 ⁶ Pa.

  Next, an aging process S103 for performing an aging process after initially charging the constrained unit cell is performed. The aging step S103 can be performed according to a known method.

  For example, each constrained unit cell 100 is initially charged to, for example, SOC 50% or more, preferably SOC 60% or more, more preferably SOC 70% or more, and further preferably SOC 90% to 100%, and an aging process is performed. The temperature of the aging treatment is preferably 60 ° C. or higher. When the temperature of the aging treatment is 60 ° C. or higher, the stress relaxation of the resin separator 16 included in the electrode body 10 is promoted, and the inter-electrode distance distribution in the electrode body after the aging treatment described later is likely to occur. The aging treatment time is preferably 5 hours or more, more preferably 10 hours to 240 hours, and further preferably 15 hours to 168 hours.

  After performing the aging step S103, the restriction between the unit cell 100 and the first cooling insulating plate 30 is released in preparation for the next second restriction step S104.

  Next, the second cooling insulating plate having the second cooling path formed by the second convex portion and the second concave portion, and the cells 100 are alternately arranged in a predetermined direction, and the arrangement direction is A second restraining step S104 for restraining in a state where a load is applied is performed.

  7 and 8 show the second cooling insulating plate 40 used in the second restraining step S104. Here, seven linear second convex portions 42 are provided, and a second concave portion 44 is formed between adjacent convex portions 42. A space on the second concave portion 44 between the adjacent convex portions 42 constitutes a second cooling path. The second cooling insulation plate 40 is preferably made of resin (eg, made of polypropylene) in order to ensure insulation.

  The arrangement and restraint of the unit cells 100 and the second cooling insulation plate 40 can be performed in the same manner as in the first restraint step S102. The same restraining member can be used in the first restraining step S102 and the second restraining step S104.

  Specifically, for example, the unit cell 100 and the second cooling insulating plate 40 are arranged as shown in FIGS. 9 and 10. Specifically, the plurality of single cells 100 are arranged in a direction in which the wide surfaces of the battery case 50 face each other. At this time, the plurality of single cells 100 are arranged in a reversed manner one by one so that the positive terminals 60 and the negative terminals 62 are alternately arranged. The second cooling insulating plate 40 is disposed between the first and last portions of the row of the unit cells 100 and the adjacent unit cells 100. Between the adjacent unit cells 100, one positive electrode terminal 60 and the other negative electrode terminal 62 are electrically connected by a connector 64.

  The unit cell 100 and the second cooling insulation plate 40 arranged in this way are restrained in a state where a load is applied in the arrangement direction. For example, a restraining member that collectively restrains the plurality of single cells 100 and the second cooling insulation plate 40 is provided around the single cells 100 and the second cooling insulation plate 40. That is, the pair of restraining plates 70A and 70B are arranged on the outer side of the second cooling insulating plate 40 located on the outermost side in the arrangement direction (first and last in the row). Further, the fastening beam member 72 is attached so as to bridge the pair of restraining plates 70A and 70B. Then, by tightening and fixing the ends of the beam member 72 to the restraining plates 70A and 70B with the screws 74, the unit cells 100 can be restrained so that a predetermined load (restraining load) is applied in the arrangement direction.

  In order for the load to be applied to the entire electrode body 10 of the unit cell 100 as much as possible, the upper side of the electrode case 10 (the side where the positive electrode terminal 60 and the negative electrode terminal 62 of the unit cell 100 are located) is upward. The distance between the portion facing the end of the cooling insulating plate 40 and the portion where the uppermost convex portion 42 of the cooling insulating plate 40 contacts the battery case is the distance between the adjacent convex portions 42 of the cooling insulating plate 40. It is preferably less than half. Similarly, the distance between the portion of the battery case 50 (the wide surface thereof) facing the lower end of the electrode body 10 and the portion where the lowermost convex portion 42 of the cooling insulating plate 40 contacts the battery case 50. Is preferably half or less of the distance between the adjacent convex portions 42 of the cooling insulating plate 40.

  Here, as can be seen from the comparison between FIG. 4 and FIG. 8 and the comparison between FIG. 6 and FIG. 10, the second convex portion 42 of the second cooling insulating plate 40 is replaced by the unit cell 100 in the second restraint step S104. The position of the first cooling insulating plate 30 in contact with the battery case 50 is different from the position in contact with the battery case 50 of the unit cell 100 in the first restraining step S102 without overlapping. Yes. Specifically, the position where the second convex portion 42 of the second cooling insulation plate 40 contacts the battery case 50 of the unit cell 100 and the second convex portion 42 adjacent thereto are the battery case 50 of the unit cell 100. The position where the first convex portion 32 of the first cooling insulating plate 30 contacts the battery case 50 of the unit cell 100 is positioned between the position where the first cooling insulating plate 30 contacts the battery case 50 (particularly just the middle position).

  The assembled battery 200 obtained as described above is normally used. However, in the assembled battery 200, metal lithium is hardly deposited during normal use, and as a result, the battery capacity is hardly reduced.

  In this way, the cooling insulating plate provided for the aging process and the cooling insulating plate provided for normal use are changed, and the positions where the convex portions of the respective cooling insulating plates are in contact with the battery case 50 of the unit cell 100 are made different. The reason why the battery capacity can be prevented from decreasing is considered as follows. FIG. 11 is a line graph showing the inter-electrode distance of the electrode body accommodated in the unit cell in the assembled battery according to the prior art. FIG. 12 is a diagram in which a line graph (thick line) indicating the distance between electrodes after the aging process is superimposed on the line graph (thin line) of FIG. FIG. 13 is a line graph showing the inter-electrode distance of the electrode body 10 accommodated in the unit cell 100 in the assembled battery 200 obtained by the manufacturing method according to the present embodiment.

  As in the prior art, using only the cooling insulation plate having the cooling path formed in the convex part and the concave part as shown in FIGS. 7 and 8, the cells are arranged and constrained, and after initial charging and aging treatment When the assembled battery is obtained, the electrode body accommodated in the unit cell has a high surface pressure in the portion facing the convex portion, but the surface pressure is hardly applied in the portion facing the concave portion. Therefore, there is a difference in applied pressure between the portion facing the convex portion and the portion facing the concave portion. Here, according to the study by the present inventors, when the distance between the positive electrode and the negative electrode (distance between the electrodes) was measured for the portion of the electrode body in contact with the cooling insulation plate, as shown in FIG. The distance between the electrodes is narrow (the valley portion of the line graph) at the portion facing the portion, and the distance between the electrodes is wide at the portion facing the recess (the peak portion of the line graph). It was found that a distribution occurred between the distances. In such a state in which the distance between the electrodes is distributed, metallic lithium is likely to be deposited at the boundary portion between the portion facing the convex portion and the portion facing the concave portion of the electrode body. It was found that is easy to decrease.

  On the other hand, as in the present embodiment, the first cooling insulating plate having the first cooling path formed by the first convex portion and the first concave portion as shown in FIGS. 3 and 4 is used. The battery is arranged and constrained, subjected to initial charging and aging treatment, and a single cooling cell is formed using a second cooling insulating plate having a cooling path formed in the convex part and the concave part as shown in FIGS. Consider the case of re-arranging and constraining. In the aging process, based on the first convex portion and the first concave portion of the first cooling insulating plate, a distribution of the inter-electrode distance as shown in the line graph drawn by a thick line in FIG. 12 is generated. On the other hand, after the assembled battery is configured, the inter-electrode distance as shown in the line graph drawn by the thin line in FIG. 12 based on the second concave portion and the second convex portion of the second cooling insulating plate. Distribution occurs.

  Here, the position where the second convex portion 42 of the second cooling insulation plate 40 contacts the battery case 50 of the unit cell 100 is the position where the first projection 32 of the first cooling insulation plate 30 is the unit cell 100. Since it differs from the position in contact with the battery case 50 without overlapping, as shown in FIG. 12, the valley of the line graph drawn with a thick line indicating the distance between the electrodes when the first cooling insulating plate 30 is used. The positions of the peaks and the peaks are different from the positions of the valleys and peaks in the line graph drawn with thin lines indicating the distance between the electrodes when the second cooling insulation plate 40 is used. For this reason, the distribution of the distance between the electrodes generated after the aging treatment using the first cooling insulating plate 30 is canceled, and the distribution of the distance between the electrodes after the assembled battery configuration is narrowed as shown in FIG. For this reason, it is considered that metallic lithium is less likely to precipitate, and as a result, the battery capacity is unlikely to decrease.

What is necessary is just to select the magnitude | size of the said restraint load suitably according to the number, size, etc. of the cell 100. FIG. For example, a load is applied and restrained so that the surface pressure applied to the wide surface of the battery case 50 of the unit cell 100 is 10 ⁴ Pa to 10 ⁶ Pa.

  The assembled battery obtained by the manufacturing method according to the present embodiment can be suitably used as a high output power source for mounting on a vehicle such as an electric vehicle (EV), a hybrid vehicle (HV), and a plug-in hybrid vehicle (PHV).

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to a following example.

<Test Example 1>
An aluminum foil is used as a positive electrode current collector, and a positive electrode active material layer (LiNi ₂₎ for a lithium ion secondary battery mainly composed of LiNi _1/3 Co _1/3 Mn _1/3 O ₂ in a predetermined region on the surface thereof by a conventional method. _1/3 Co _1/3 Mn _1/3 O ₂ 88% by mass, acetylene black 10% by mass, polyvinylidene fluoride 2% by mass) to form a positive electrode sheet.
Moreover, a copper foil is used as a negative electrode current collector, and a negative electrode active material layer for lithium ion batteries mainly composed of graphite in a predetermined region on its surface (98% by mass of graphite, 1% by mass of styrene butadiene rubber, carboxymethylcellulose) 1% by mass) to form a negative electrode sheet.
These positive and negative electrode sheets were laminated together with a polyethylene separator sheet (two sheets), wound, and then crushed to produce a flat wound electrode body.
The lead electrode of each positive and negative electrode was welded to the produced wound electrode body, and it accommodated in the aluminum box-type battery case of the shape corresponding to a wound electrode body. An appropriate amount of non-aqueous electrolyte (electrolyte obtained by dissolving LiPF ₆ having a concentration of 1M as a lithium salt in a mixed solvent of ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate having a mass ratio of 1: 1: 1) is injected into the battery case. And sealed.
In this way, a lithium ion secondary battery as a single battery was obtained.

As shown in FIG. 5, using the cooling insulating plate having the shape shown in FIGS. 3 and 4, the cells and the cooling insulating plate were arranged and restrained by the restraining member so that a restraining pressure was applied in the arranging direction.
Subsequently, this was initially charged until SOC reached 90%, and then subjected to aging treatment at 65 ° C. for 160 hours.

  Next, using the cooling insulating plate having the shape shown in FIGS. 7 and 8, the cells and the cooling insulating plate are arranged as shown in FIG. 9, and restrained by the restraining member so that the restraining pressure is applied in the arranging direction. Then, an assembled battery according to Test Example 1 was produced.

<Test Example 2>
A single cell was produced in the same manner as in Test Example 1.
Next, using the cooling insulating plate having the shape shown in FIGS. 7 and 8, the cells and the cooling insulating plate are arranged as shown in FIG. 9, and restrained by the restraining member so that the restraining pressure is applied in the arranging direction. .
Next, this was initially charged until the SOC reached 90%, and then subjected to an aging treatment at 65 ° C. for 160 hours to produce an assembled battery according to Test Example 2.

[Pulse cycle test]
After measuring the initial capacity of the assembled batteries according to Test Example 1 and Test Example 2, the battery was adjusted to an SOC of 80% in a 25 ° C. environment. Then, for this battery, under the environment of −10 ° C., pulse charging with a constant current of 50 C for 10 seconds → pause for 1 minute → pulse discharge with a constant current of 50 C for 10 seconds → pause for 1 minute with one cycle. The discharge was repeated 3000 cycles. Thereafter, the capacity (capacity after the pulse cycle test) was measured, and the amount of capacity decrease before and after the pulse cycle test was calculated.
The results are shown in FIG.

  Test Example 1 is an example of an assembled battery manufactured according to the manufacturing method according to the present embodiment, and Test Example 2 is an example of an assembled battery manufactured by a conventional method. FIG. 14 shows that the assembled battery of Test Example 1 has a smaller capacity drop after the pulse cycle test under the condition where metallic lithium is likely to precipitate, compared to the assembled battery of Test Example 2. Therefore, it can be seen that according to the manufacturing method according to the present embodiment, an assembled battery in which the capacity is hardly reduced can be obtained.

  As mentioned above, although the specific example of this invention was demonstrated in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

DESCRIPTION OF SYMBOLS 10 Electrode body 12 Positive electrode sheet 14 Negative electrode sheet 16 Separator 30 1st cooling insulating plate 32 1st convex part 34 1st recessed part 40 2nd cooling insulating plate 42 2nd convex part 44 2nd recessed part 50 Battery case 60 positive electrode terminal 62 negative electrode terminal 100 cell 200 assembled battery

Claims (1)

A preparation step of preparing a plurality of unit cells, comprising an electrode body in which a positive electrode sheet and a negative electrode sheet are laminated via a separator, an electrolyte, and a battery case containing the electrode body and the electrolyte;
The first cooling insulating plate having the first cooling path formed by the first convex portion and the first concave portion and the unit cells are alternately arranged in a predetermined direction, and a load is applied in the arrangement direction. A first restraining step of restraining in a restrained state;
An aging step of performing an aging treatment after initially charging the constrained unit cell;
The second cooling insulating plate having the second cooling path formed by the second convex portion and the second concave portion and the unit cells are alternately arranged in a predetermined direction, and a load is applied in the arrangement direction. A battery assembly manufacturing method including a second restraining step of restraining in a restrained state,
The position at which the second convex portion of the second cooling insulation plate contacts the battery case of the unit cell in the second restraining step is the first position of the first cooling insulation plate in the first restraining step. Is different from the position where the convex part of the battery contacts the battery case without overlapping,
A method for producing an assembled battery.

Images