Method for manufacturing nonaqueous electrolyte secondary battery

Abstract

A method for manufacturing a nonaqueous electrolyte secondary battery includes a step for obtaining a battery assembly, a charging step, and a sealing step. In the battery assembly, an electrode body including a positive electrode and a negative electrode, and a non-aqueous electrolyte solution are housed in a battery case having a through-hole. In the charging step, the battery assembly is charged. In the sealing step, after the charging step, the through-hole is sealed by a sealing member. In the charging step, charging is performed under charging conditions in which the temperature of the gas in the battery case increases. The sealing step is performed while maintaining a temperature rise in the battery case. After the sealing step, the temperature in the battery case is reduced, and the contraction of the battery case and / or the reduction of the internal pressure are / is generated by the contraction of the gas in the battery case.

Description

Technical Field

[0001] This invention relates to a method for manufacturing non-aqueous electrolyte secondary batteries. Background Technology

[0002] Japanese Patent Application Publication No. 2018-163858 discloses a method for manufacturing a square secondary battery. In this method, after an electrolyte injection step (injecting a non-aqueous electrolyte), a charging step and a gas venting step are performed. In the charging step, the battery is charged. In the gas venting step, a portion (15% or more) of the gas inside the casing is vented from the injection hole to the outside of the battery casing.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-163858 Summary of the Invention

[0006] The inventors aim to suppress the expansion of non-aqueous electrolyte secondary batteries.

[0007] The method for manufacturing a non-aqueous electrolyte secondary battery disclosed herein includes a process of obtaining a battery assembly, a charging process, and a sealing process. The battery assembly houses electrode bodies including a positive electrode and a negative electrode, as well as a non-aqueous electrolyte, within a battery casing having a through-hole. In the charging process, the battery assembly is charged. In the sealing process, after the charging process, the through-hole is sealed by a sealing member. In the charging process, charging is performed under charging conditions where the temperature of the gas inside the battery casing rises. The sealing process is performed while maintaining the temperature rise inside the battery casing. After the sealing process, the temperature inside the battery casing decreases, resulting in the contraction of the battery casing and / or a reduction in internal pressure due to the contraction of the gas inside the battery casing. According to this manufacturing method, the expansion of the manufactured non-aqueous electrolyte secondary battery can be suppressed. Attached Figure Description

[0008] Figure 1 This is a flowchart illustrating the manufacturing method of a non-aqueous electrolyte secondary battery.

[0009] Figure 2 This is a three-dimensional view of a battery assembly (non-aqueous electrolyte secondary battery) 100.

[0010] Figure 3 It is along Figure 2 A schematic cross-sectional view of line III-III in the diagram.

[0011] Figure 4 This is a schematic diagram of electrode body 40.

[0012] Figure 5This is a three-dimensional view of electrode body 40.

[0013] Figure 6 This is a perspective view of the electrode body 40 installed on the cover 54.

[0014] Figure 7 This is a schematic diagram showing the state of gas G inside the battery casing 50.

[0015] Figure 8 This is a schematic diagram showing the state of gas G inside the battery casing 50.

[0016] Figure 9 This is a flowchart illustrating a method for manufacturing a non-aqueous electrolyte secondary battery according to other embodiments.

[0017] Figure 10 This is a cross-sectional view of the battery assembly 100 in the pressure reduction process S25. Detailed Implementation

[0018] Hereinafter, an embodiment of the technology disclosed herein will be described with reference to the accompanying drawings. The embodiments described herein are not intended to limit the invention. The drawings are schematic and do not necessarily reflect the actual object. Furthermore, components and parts that perform the same function are appropriately labeled with the same reference numerals, and repeated descriptions are omitted where appropriate. In the following description, reference numerals L, R, F, Rr, U, and D in the drawings represent left, right, front, back, top, and bottom, respectively, and reference numerals X, Y, and Z in the drawings represent the short side direction, long side direction, and height direction of the non-aqueous electrolyte secondary battery (battery assembly), respectively. However, these directions are only for ease of explanation and do not limit the arrangement of the non-aqueous electrolyte secondary battery, etc. In this specification, the expression "A to B" indicating a range includes "above A and below B," and also includes "greater than A" and "less than B."

[0019] The following explanation will focus on the manufacturing method of the non-aqueous electrolyte secondary battery disclosed herein, using the case of a lithium-ion secondary battery as an example.

[0020] <Manufacturing Method of Non-Aqueous Electrolyte Secondary Batteries>

[0021] Figure 1 This is a flowchart illustrating a manufacturing method for a non-aqueous electrolyte secondary battery. For example... Figure 1 As shown, the method for manufacturing a non-aqueous electrolyte secondary battery disclosed herein includes a step S10 for obtaining a battery assembly, a charging step S20, and a sealing step S30.

[0022] <Process S10 for obtaining the battery assembly>

[0023] In step S10 of obtaining the battery assembly, a battery assembly 100 is obtained in which an electrode body 40 including a positive electrode 10 and a negative electrode 20 and a non-aqueous electrolyte are housed in the battery casing 50.

[0024] Figure 2 This is a three-dimensional view of a battery assembly (non-aqueous electrolyte secondary battery) 100. Figure 3 It is along Figure 2 A schematic cross-sectional view of line III-III in the diagram. Figure 4 This is a schematic diagram of electrode body 40. Figure 5 This is a three-dimensional view of electrode body 40. Figure 6 This is a perspective view of the electrode body 40 mounted on the cover 54. Furthermore, the non-aqueous electrolyte secondary battery has the same structure as the battery assembly, except that it is equipped with the sealing member 56.

[0025] <Battery Assembly 100>

[0026] like Figure 3 As shown, the battery assembly 100 includes a battery casing 50 that houses the electrode body 40 and a non-aqueous electrolyte (not shown). In this specification, the battery assembly 100 is formed by assembling the constituent elements of a non-aqueous electrolyte secondary battery 100 (hereinafter simply referred to as "battery") and injecting a non-aqueous electrolyte. Hereinafter, the same reference numerals will be used to describe the non-aqueous electrolyte secondary battery and the battery assembly. Furthermore, in this specification, the battery assembly 100 is the structure prior to initial charging and before sealing the through-hole 55 after the injection of the non-aqueous electrolyte.

[0027] <Battery casing 50>

[0028] Battery casing 50 (reference) Figure 2 , 3 It has a through hole 55. The battery casing 50 can be made of conventionally known materials without particular limitation. For example, the battery casing 50 can be made of metal. Examples of materials for the battery casing 50 include aluminum, aluminum alloy, iron, and iron alloy. Although not particularly limited, the battery casing 50 is preferably made of aluminum or aluminum alloy. In this embodiment, the battery casing 50 is square (cubic parallelepiped). The battery casing 50 has a casing body 52 and a cover 54.

[0029] The housing body 52 has: a bottom wall 52a that is generally rectangular in plan view; a pair of first side walls 52b extending upward in the height direction Z from the long side of the bottom wall 52a; and a pair of second side walls 52c extending upward in the height direction Z from the short side of the bottom wall 52a (see reference). Figure 2 An opening 52h is formed in the upper part of the shell body 52.

[0030] The cover 54 is a plate-shaped member that is generally rectangular in plan view. The cover 54 is a member that blocks the opening 52h of the housing body 52. ​​A through hole 55 and a gas vent valve 57 are provided on the cover 54. The through hole 55 is preferably an injection hole for injecting a non-aqueous electrolyte (not shown) into the interior of the battery housing 50. After the non-aqueous electrolyte injection is completed, the through hole 55 is sealed by a sealing member 56. The injection of the non-aqueous electrolyte will be described later. In this embodiment, the through hole 55 is provided on the cover 54, but this is not a limitation. The through hole 55 may also be provided on the housing body 52. ​​The gas vent valve 57 is a thin-walled portion designed to break (open) and vent the gas when a large amount of gas is generated inside the battery housing 50.

[0031] The cover 54 has terminal insertion holes 58 and 59 for mounting the positive terminal 60 and the negative terminal 65, respectively. The terminal insertion holes 58 and 59 are formed at the ends of the cover 54 in the Y direction along its long side.

[0032] The positive terminal 60 and the negative terminal 65 are respectively mounted on the ends of the cover 54 along the long side Y direction of the battery 100. The positive terminal 60 is connected to the plate-shaped positive external conductive member 62 on the outside of the battery casing 50. The negative terminal 65 is connected to the plate-shaped negative external conductive member 67 on the outside of the battery casing 50. The positive external conductive member 62 and the negative external conductive member 67 are connected to other energy storage devices and external equipment via external connecting members (busbars, etc.).

[0033] A positive first current collector 71 and a negative first current collector 76 are mounted on the inner side of the cover 54. The positive first current collector 71 and the negative first current collector 76 are plate-shaped conductive members extending along the inner side of the cover 54. The lower end 60c of the positive terminal 60 is connected to the positive first current collector 71. The lower end 65c of the negative terminal 65 is connected to the negative first current collector 76.

[0034] Various insulating members are provided on the cover 54 to prevent conductivity between the battery casing 50 (casing body 52, cover 54) and the electrode terminals (positive terminal 60, negative terminal 65). Gaskets 90 are installed in the terminal insertion holes 58 and 59 of the cover 54 to prevent conductivity between the electrode terminals and the cover 54. An external insulating member 92 is disposed between the positive electrode external conductive member 62 (or the negative electrode external conductive member 67) and the outer surface of the cover 54. An internal insulating member 94 is disposed between the positive electrode first current collector 71 (or the negative electrode first current collector 76) and the inner surface of the cover 54. The internal insulating member 94 has a plate-shaped base 94a mounted on the inner surface of the cover 54. The internal insulating member 94 has a protrusion 94b protruding from the base 94a toward the electrode body 40. The protrusion 94b restricts the vertical movement of the electrode body 40, preventing direct contact between the electrode body 40 and the cover 54. The material of the above-mentioned insulating members is not particularly limited as long as it has the specified insulation properties. As an insulating component, synthetic resin materials such as polyolefin resins and fluorinated resins can be used.

[0035] With the electrode body 40 installed via the positive current collector 70 and the negative current collector 75, the cover 54 is installed on the upper part of the housing body 52 to seal the opening 52h.

[0036] <Electrode 40>

[0037] like Figure 4 As shown, the electrode body 40 is a flat electrode body formed by winding a strip-shaped positive electrode 10 and a strip-shaped negative electrode 20 through a strip-shaped separator 30. In this embodiment, the electrode body 40 is a so-called wound electrode body. Not limited to this method, the electrode body 40 may also be a stacked electrode body formed by alternately stacking multiple positive and negative electrodes through separators.

[0038] <Positive Electrode 10>

[0039] The positive electrode 10 is a long, strip-shaped component. The positive electrode 10 includes a positive electrode core 12 as a foil-shaped metal component and a positive electrode active material layer 14 formed on the surface of the positive electrode core 12. From the viewpoint of battery performance, the positive electrode active material layer 14 is preferably formed on both sides of the positive electrode core 12. An outer side facing the Y direction is provided at one side edge of the positive electrode 10. Figure 4 The positive electrode tab 12t protrudes from the left side of the positive electrode 10. Multiple positive electrode tabs 12t are provided at predetermined intervals along the length of the positive electrode 10. These positive electrode tabs 12t represent the areas where the positive electrode core 12 is exposed before the formation of the positive electrode active material layer 14 and the protective layer 16. The positive electrode core 12 is preferably made of a metallic material with a predetermined conductivity. For example, the positive electrode core 12 is preferably made of aluminum, aluminum alloy, etc.

[0040] The positive electrode active material layer 14 is a layer containing the positive electrode active material. The positive electrode active material is a material capable of reversibly adsorbing and releasing charge carriers in relation to the negative electrode active material (described later). There are no particular limitations on the positive electrode active material. For example, a lithium transition metal composite oxide is preferably used as the positive electrode active material.

[0041] The positive electrode active material layer 14 may also contain additives other than the positive electrode active material. The positive electrode active material layer 14 may contain a binder. A resin binder is preferably used as the binder. For example, polyvinylidene fluoride (PVDF) is preferably used as the resin binder. The positive electrode active material layer 14 preferably contains a conductive material. A carbon material such as acetylene black (AB) is preferably used as the conductive material.

[0042] Alternatively, a protective layer 16 may be provided on one side edge of the positive electrode 10 as needed. The protective layer 16 is configured to have a lower conductivity than the positive electrode active material layer 14. The protective layer 16 is disposed on the positive electrode core 12 facing the negative electrode active material layer 24 across the separator 30. Although the structure of the protective layer 16 is not particularly limited, it may be, for example, a layer coated with resin, a layer containing inorganic particles, or a binder.

[0043] <Negative Electrode 20>

[0044] The negative electrode 20 is a long, strip-shaped component. The negative electrode 20 includes a negative electrode core 22 as a foil-shaped metal component and a negative electrode active material layer 24 formed on the surface of the negative electrode core 22. From the viewpoint of battery performance, the negative electrode active material layer 24 is preferably formed on both sides of the negative electrode core 22. An outer side facing the Y direction is provided on one side edge of the negative electrode 20. Figure 4 The negative electrode tab 22t protrudes from the right side of the negative electrode 20. The negative electrode tab 22t protrudes to the opposite side of the aforementioned positive electrode tab 12t. Multiple negative electrode tabs 22t are provided at predetermined intervals along the length of the negative electrode 20. This negative electrode tab 22t is the area where the negative electrode core 22 is exposed before the formation of the negative electrode active material layer 24. As the negative electrode core 22, a metallic material with a predetermined conductivity is preferably used. The negative electrode core 22 is preferably made of, for example, copper, a copper alloy, etc.

[0045] The negative electrode active material layer 24 is a layer containing negative electrode active material. The negative electrode active material is a material capable of reversibly adsorbing and releasing charge carriers in relation to the positive electrode active material. There are no particular limitations on the negative electrode active material. For example, carbon materials, silicon-based materials, and mixed oxides thereof are preferred as negative electrode active materials. For example, graphite, hard carbon, soft carbon, and amorphous carbon can be used. Examples of silicon-based materials include silicon and silicon oxide (silicon dioxide).

[0046] The negative electrode active material layer 24 may also contain additives other than the negative electrode active material. The negative electrode active material layer 24 may contain a binder as an additive. A resin binder is preferably used as the binder. Examples of resin binders that may be used include styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), and polyacrylic acid (PAA). The negative electrode active material layer 24 preferably contains a conductive material. Carbon materials such as acetylene black (AB) and carbon nanotubes are preferably used as the conductive material.

[0047] <Septum 30>

[0048] The diaphragm 30 is a long, strip-shaped component that prevents the positive electrode 10 from contacting the negative electrode 20 and allows charge carriers to pass through. The width of the diaphragm 30 can be set to cover the positive electrode active material layer 14 of the positive electrode 10 and the negative electrode active material layer 24 of the negative electrode 20.

[0049] The diaphragm 30 is preferably a porous membrane made of resin having multiple fine pores that allow charge carriers to pass through. Examples of diaphragms 30 include porous sheets (films) made of polyolefins such as polyethylene (PE) and polypropylene (PP), or resins such as polyamide. The porous sheet can be a single-layer structure or a laminated structure of two or more layers (for example, a three-layer structure formed by laminating PP layers on both sides of a PE layer).

[0050] A heat-resistant layer may also be formed on the resin sheet constituting the diaphragm 30. This heat-resistant layer is one with excellent heat resistance. Preferably, the heat-resistant layer comprises ceramic particles and a binder. For example, alumina can be used as one of the ceramic particles.

[0051] The diaphragm 30 may also include an adhesive layer. The adhesive layer is a layer with excellent adhesion to the electrode plates (positive electrode 10, negative electrode 20). Known materials can be used as the adhesive layer. Resin-based materials can also be used. The adhesive layer may, for example, contain an adhesive such as polyvinylidene fluoride. The adhesive layer may also contain ceramic particles.

[0052] The positive electrode tab group 42 and the negative electrode tab group 44 protrude from the electrode body 40 along the winding axis WL. The positive electrode tab group 42 and the negative electrode tab group 44 protrude from different sides in opposite directions. Figure 5 As shown, a second positive current collector 72 and a second negative current collector 77 are connected to the positive electrode tab group 42 and the negative electrode tab group 44, respectively. Figure 6As shown, the positive electrode tab assembly 42 is bent and connected to the cover 54 via the first positive current collector 71 and the second positive current collector 72. Similarly, the negative electrode tab assembly 44 is bent and connected to the cover 54 via the first negative current collector 76 and the second negative current collector 77. Furthermore, the first positive current collector 71 and the second positive current collector 72 constitute the positive current collector 70, and the first negative current collector 76 and the second negative current collector 77 constitute the negative current collector 75. In this embodiment, a plurality of (3) electrode bodies 40 are housed in the housing body 52 in a state of being mounted on the cover 54 (see reference). Figure 3 The number of electrode bodies 40 housed in the battery casing 50 is not particularly limited.

[0053] like Figure 2 As shown, after the electrode body 40 is stored, the periphery of the cover 54 is installed on the upper part of the housing body 52, and the opening 52h of the housing body 52 (refer to...) Figure 3 The opening 52h is sealed. The cover 54 can be mounted on the upper part of the housing body 52, for example, by laser welding. After the opening 52h is sealed, a non-aqueous electrolyte is injected through the through-hole 55 of the battery housing 50.

[0054] <Non-aqueous electrolyte>

[0055] As a non-aqueous electrolyte, it can be used without particular restrictions in electrolytes conventionally known for use in secondary batteries. The non-aqueous electrolyte can be an electrolyte formed by dissolving a supporting salt in a non-aqueous solvent. As the non-aqueous solvent, carbonate solvents such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate can be used. As the supporting salt, fluorinated lithium salts such as LiPF6 can be used. Various additives such as gas generators, film-forming agents, dispersants, and thickeners can also be included as needed.

[0056] The injection of non-aqueous electrolyte can be carried out under pre-set conditions. Although not illustrated, the injection of non-aqueous electrolyte can be carried out under reduced pressure. For example, the non-aqueous electrolyte can be injected into the battery housing 50 within a vacuum chamber. A vacuum pump for reducing pressure within the chamber can also be connected to the chamber.

[0057] First, the battery casing 50 is housed in the chamber. Next, the chamber is adjusted to a predetermined depressurization state. Then, an injection nozzle (not shown) is inserted into the through hole 55 of the battery casing 50 (see reference). Figure 3 In a depressurized state, a non-aqueous electrolyte is injected. When the non-aqueous electrolyte is injected into the battery casing 50, it begins to impregnate the electrode body 40. By injecting the non-aqueous electrolyte under reduced pressure, it is easier for the non-aqueous electrolyte to impregnate the electrode body 40. As a result, the time required for the non-aqueous electrolyte to completely impregnate the electrode body 40 can be shortened. Furthermore, the environment during injection is not particularly limited. It can also be configured to allow the introduction of inactive gases such as nitrogen or air into the chamber.

[0058] After injecting the non-aqueous electrolyte into the battery assembly 100, the initial charging is then carried out.

[0059] <Charging process S20>

[0060] In charging process S20 (refer to) Figure 1 In this process, the battery assembly 100 is charged. The charging step S20 is preferably an initial charge (exhaust charge) for pre-generating gas from the electrode (negative electrode) surface. The charging step S20 can be performed under pre-set charging conditions.

[0061] The charging conditions are performed under conditions where the temperature of the gas inside the battery casing 50 rises. In this embodiment, the initial charging is performed at a room temperature of around 25°C (e.g., 20°C to 30°C). The initial charging is performed in a nitrogen atmosphere. During charging, the electrode body 40 and the like can generate heat inside the battery casing 50. As a result, the temperature of the gas inside the battery casing 50 rises. In this embodiment, the charging conditions are set such that the temperature of the gas inside the battery casing 50 reaches 35°C or higher. The charging conditions can also be set such that the temperature of the gas inside the battery casing 50 reaches 40°C or higher. However, from the viewpoint of battery performance, an upper limit for the temperature of the gas inside the battery casing 50 can be set. For example, the upper limit for the temperature of the gas inside the battery casing 50 can be set to 60°C or 55°C. By setting such charging conditions, in the sealing process S30 described later (see...), Figure 1 In this case, the through hole 55 can be easily sealed when the temperature inside the battery casing 50 is high.

[0062] The temperature inside the battery casing 50 during charging is not limited to the temperature described above. The temperature inside the battery casing 50 during charging can also be set according to the temperature of the intended environment. For example, the temperature inside the battery casing 50 during charging can be set to be at least 10°C higher than the intended environment temperature. In this embodiment, the temperature inside the battery casing 50 during charging is set to 35°C, which is at least 10°C higher than the ambient temperature of the intended battery 100 (25°C).

[0063] Furthermore, there are no particular limitations on the method for obtaining the temperature of the gas inside the battery casing 50. The temperature of the gas inside the battery casing 50 can also be obtained based on the temperature of the battery casing 50. For example, the relationship between the temperature of the gas inside the battery casing 50 and the temperature of the battery casing 50 can be determined in advance as follows: First, prepare a test battery assembly with the target structure. Charge the test battery assembly under initial charging conditions. Obtain the temperature of the gas inside the battery casing and the temperature of the battery casing during charging. The temperature inside the battery casing 50 can also be estimated based on the relationship between the temperature of the gas inside the battery casing and the temperature of the battery casing obtained through experiments. Alternatively, the temperature of the gas inside the battery casing 50 can also be directly measured using a temperature sensor (thermocouple, etc.). For example, a tiny opening can be formed in the battery casing 50, and a thermocouple can be inserted into the opening without contacting the electrode body 40. Alternatively, the opening can be blocked, and the temperature inside the battery casing 50 can be obtained using a thermocouple.

[0064] The battery assembly 100 can be charged at a constant current of 60A or more (so-called CC charging). By charging the battery assembly 100 with a constant current, voltage adjustment is no longer required, and the time required for initial charging can be shortened. Furthermore, it is easier to calculate the amount of charge during the initial charging and to adjust the amount of charge during subsequent charging. From the viewpoint of rapidly increasing the temperature of the battery assembly 100, a higher charging current is preferable. While not particularly limited, the charging current is preferably 60A or more, more preferably 80A or more, and can also be 100A or more. While not particularly limited, the charging current can be set to 300A or less.

[0065] The battery assembly 100 can be charged until the State of Charge (SOC) reaches a preset capacity or the inter-terminal voltage reaches a preset value. The SOC and inter-terminal voltage values ​​can be appropriately set depending on the type of battery 100, etc. The charging time can be 600 seconds or more. While not particularly limited, a charging time of 300 seconds or more is preferred, and 900 seconds or more is also acceptable. From a production efficiency point of view, the charging time should preferably not be too long. While not particularly limited, the charging time can be 60 minutes or less, for example, 30 minutes or less.

[0066] Initial charging can be performed in a single charge or in multiple charges (though there is no particular limitation, it can be performed in approximately 2 to 5 charges). When performing initial charging in multiple charges, the average charging current during the charging time can be set to 60A or higher. Furthermore, initial charging does not necessarily need to be performed using the constant current method described above. Initial charging can also be performed using a so-called CC-CV charging method, where a constant current is first applied, followed by a constant voltage application after a preset voltage is reached. Charging conditions can be appropriately set according to the type and size of the battery 100.

[0067] From the viewpoint of easily venting gas from the battery casing 50, it is preferable to open the through hole 55 during the charging process S20.

[0068] <Sealing process S30>

[0069] In sealing process S30 (refer to...) Figure 1 In the process, the through hole 55 is sealed by the sealing member 56. The sealing process S30 is performed while maintaining a temperature rise within the battery casing 50. The sealing process S30 can be performed at atmospheric pressure (standard atmospheric pressure). The sealing process S30 can be performed at room temperature or at a temperature higher than room temperature. The method for sealing the through hole 55 by the sealing member 56 is not particularly limited. For example, a blind hole rivet can be used as the sealing member 56.

[0070] In the sealing process S30, the through hole 55 is sealed while preventing the temperature of the gas inside the battery casing 50 from decreasing from the highest temperature of the gas inside the battery casing 50 in the charging process S20. The through hole 55 is sealed while the temperature inside the battery casing 50 is higher than room temperature. The through hole 55 is preferably sealed immediately after charging is completed to minimize the temperature drop inside the battery casing 50. The through hole 55 can be sealed before it drops below a predetermined temperature from the highest temperature of the gas inside the battery casing 50 in the charging process S20. The through hole 55 is preferably sealed by the sealing member 56 before the temperature drops by more than 2°C from the highest temperature of the gas inside the battery casing 50 in the charging process S20, and more preferably before it drops by more than 1°C. The sealing process S30 is preferably performed immediately after the charging process S20. As a result, the temperature difference inside the battery casing 50 can easily increase between when the through hole 55 is sealed and when the battery 100 is in use.

[0071] After sealing the through hole 55, a non-aqueous electrolyte secondary battery 100 is manufactured by aging and other processes using known methods.

[0072] Furthermore, non-aqueous electrolyte secondary batteries may gradually expand due to repeated charging and discharging over long-term use. If the non-aqueous electrolyte secondary battery expands, the space for its placement may be compressed. Additionally, in cases where high capacity is desired, multiple non-aqueous electrolyte secondary batteries may be arranged along one direction (e.g., the shorter side) and used in a constrained manner. In this case, if multiple non-aqueous electrolyte secondary batteries expand, the space for their placement may be further compressed.

[0073] In the above manufacturing method, in the non-aqueous electrolyte secondary battery 100, the through hole 55 is sealed while the temperature inside the battery casing 50 is higher than room temperature. Therefore, after the sealing process S30, the temperature inside the battery casing 50 decreases, and the gas inside the battery casing 50 contracts. This results in the contraction of the battery casing 50 and / or a reduction in internal pressure. The contraction of the battery casing 50 and the reduction in internal pressure will be explained below.

[0074] After the through hole 55 is sealed when the temperature inside the battery casing 50 is higher than normal, the battery 100 is placed in a normal temperature environment and the temperature drops. Figure 7 and Figure 8 This is a schematic diagram showing the state of gas G inside the battery casing 50. Figure 7 and Figure 8 In this version, components other than the battery casing 50 and the electrode body 40 are omitted. Figure 7 and Figure 8 The diagram schematically illustrates the internal pressure within the battery casing 50 before and after a temperature decrease. The decrease in internal pressure is shown as a reduction in the density of the mesh dots. Figure 7 This is a schematic diagram showing the situation where there is a gap A between the electrode body 40 and the first sidewall 52b when the through hole 55 is sealed. Figure 8 This is a schematic diagram showing the situation where there is no gap between the electrode body 40 and the first sidewall 52b when the through hole 55 is sealed. Furthermore, Figure 7 and Figure 8 This is merely an illustrative representation of the deformation of the battery casing 50 and the change in internal pressure before and after the temperature decreases; it does not necessarily mean that only one of these phenomena occurs.

[0075] As the temperature of battery 100 decreases, the gas G inside battery casing 50 will contract. For example... Figure 7 As shown, when there is a gap A between the electrode body 40 and the first sidewall 52b, the battery casing 50 can deform in such a way that the gap A narrows (in other words, the distance between the pair of first sidewalls 52b narrows) as the gas G contracts. This makes it easier to reduce the thickness of the battery 100. Furthermore, when the electrode body 40 comes into contact with the first sidewall 52b due to the deformation of the battery casing 50, the internal pressure of the battery casing 50 can decrease as the temperature further decreases.

[0076] like Figure 8As shown, when there is no gap between the electrode body 40 and the first sidewall 52b (or, when the gap disappears due to the contraction of the battery casing 50), the battery casing 50 is difficult to deform even when the gas G contracts. Therefore, the volume of the gas G is difficult to deform. Instead, the internal pressure of the gas G can be reduced. Due to the pressure difference between the inside and outside of the battery casing 50, the expansion of the battery casing 50 caused by the increase in internal pressure is less likely to occur.

[0077] The higher the temperature inside the battery casing 50 when the through hole 55 is sealed, the greater the temperature difference before and after sealing. When multiple electrode bodies 40 are housed in the battery casing 50, the temperature inside the battery casing 50 is maintained at a high level, thus achieving the aforementioned effect. Furthermore, the larger the electrode body 40 is relative to the internal volume of the battery casing 50, the better the aforementioned effect is achieved.

[0078] Furthermore, the less gas present within the battery casing 50, the more effective the suppression of expansion of the battery casing 50. The smaller the internal volume of the battery casing 50 after filling with non-aqueous electrolyte, relative to its empty volume, the greater the potential for deformation and internal pressure reduction in the battery casing 50. For example, the internal volume of the battery casing 50 after filling with non-aqueous electrolyte is preferably 50 cm³. 3 The following refers to the volume of the space within the battery casing 50 after deducting the volume of the empty battery casing 50 from the volume of the battery casing 50 itself, including the electrode body 40, non-aqueous electrolyte, and other structures disposed within the battery casing 50. Furthermore, the volume of the space within the battery casing 50 is preferably 10% or less of the volume of the empty battery casing 50. In this embodiment, the dimension of the battery casing 50 in the short side direction X is approximately 30 mm, the dimension in the long side direction Y is approximately 308 mm, and the dimension in the height direction Z is 90 mm. The volume of the space within the battery casing 50 is 42.1 cm³. 3 The volume of the space inside the battery casing 50 is 5.1% of the volume of the battery casing 50 in its empty state. When a gap A is provided between the electrode body 40 and the first sidewall 52b, the size of the gap A is preferably 15 mm or less on one side (for example, 30 mm or less on both sides combined).

[0079] In the above-described method for manufacturing a non-aqueous electrolyte secondary battery, the battery casing shrinks and / or the internal pressure decreases due to the temperature difference before and after charging and sealing. According to this method, the shrinkage of the battery casing and / or the reduction of internal pressure can be achieved non-contactly. Furthermore, no additional equipment is needed to deform the battery casing or reduce the internal pressure. For example, there is no need for processing that directly constrains the battery casing. Therefore, the device structure is simplified, and the cost of the non-aqueous electrolyte secondary battery can be reduced.

[0080] Furthermore, in the above embodiment, the sealing process S30 is performed after the charging process S20. In addition to the charging process S20 and the sealing process S30, other processes may be added.

[0081] Figure 9 This is a flowchart illustrating a method for manufacturing a non-aqueous electrolyte secondary battery according to other embodiments. Figure 10 This is a cross-sectional view of the battery assembly 100 in the pressure reduction process S25. (Example) Figure 9 As shown, the manufacturing method of a non-aqueous electrolyte secondary battery may also include a pressure reduction step S25. Furthermore, the steps S10 for obtaining the battery assembly, the charging step S20, and the sealing step S30 are the same as in the embodiment described above, and therefore descriptions are omitted.

[0082] In this embodiment, a pressure reduction step S25 is performed between the charging step S20 and the sealing step S30 to reduce the pressure inside the battery casing 50. In the pressure reduction step S25, as... Figure 10 As shown, the nozzle 111 of the pressure reducing device 110 is inserted into the through hole 55. A vacuum pump can be used, for example, as the pressure reducing device 110. Gas is drawn from the battery casing 50 through the nozzle 111. This reduces the amount of gas inside the battery casing 50. As a result, the internal pressure of the battery casing 50 is more easily reduced after the sealing process S30, and the expansion of the battery casing 50 is more easily suppressed. In this embodiment, the outer diameter of the nozzle 111 is approximately the same as the inner diameter of the through hole 55. Pressure is reduced inside the battery casing 50 while the outer peripheral surface of the nozzle 111's tip is in close contact with the inner peripheral surface of the through hole 55. By reducing pressure inside the battery casing 50 by keeping the nozzle 111 in close contact with the through hole 55, gas is less likely to flow into the battery casing 50. As a result, the pressure reducing efficiency can be improved. Furthermore, by not deeply inserting the tip of the nozzle 111 into the battery casing 50, the electrode body 40 and the like housed inside the battery casing 50 are less likely to be damaged. However, the method of reducing pressure inside the battery casing 50 is not limited to this method.

[0083] In this embodiment, pressure is reduced within the battery casing 50 by inserting a nozzle 111 into the through-hole 55. In this method, it is not necessary to move the battery assembly 100 to a dedicated pressure-reducing device. The pressure-reducing step S25 can be performed immediately after the charging step S20. Therefore, it is easy to perform the pressure-reducing step S25 while maintaining a high temperature within the battery casing 50. Maintaining a high temperature within the battery casing 50 is also easier when sealing the through-hole 55 (sealing step S30). As a result, it is easier to induce contraction of the battery casing 50 and / or a reduction in internal pressure.

[0084] Furthermore, the charging process S20 and the depressurization process S25 can be performed simultaneously. In other words, the depressurization process S25 can also be incorporated into the charging process S20. There is no particular limitation on the timing of initiating depressurization within the battery casing 50. By simultaneously performing the charging process S20 and the depressurization process S25, the depressurization time can be extended. As a result, the gas inside the battery casing 50 is further reduced. Consequently, it is easier to generate contraction of the battery casing 50 and / or a reduction in internal pressure.

[0085] The decompression process S25 can start before, after, or simultaneously with the start of charging of the battery assembly 100.

[0086] The depressurization within the battery casing 50 preferably ends simultaneously with the completion of charging of the battery assembly 100. From the viewpoint of maintaining a high temperature within the battery casing 50, the depressurization within the battery casing 50 preferably ends before the completion of charging of the battery assembly 100. However, from the viewpoint of reducing the gas content within the battery casing 50, the time gap between the end of depressurization within the battery casing 50 and the end of charging of the battery assembly 100 should preferably not be too large. For example, the time difference between the end of depressurization within the battery casing 50 and the end of charging of the battery assembly 100 is preferably within 60 seconds, more preferably within 30 seconds. It is even more preferable that the end of depressurization within the battery casing 50 and the end of charging of the battery assembly 100 are simultaneous.

[0087] While there are no particular limitations on the pressure reduction conditions, the output of the pressure reduction device 110 can be set to bring the pressure inside the battery casing 50 to approximately 0.0001 to 0.1 atmospheres. Furthermore, from the viewpoint of sufficiently reducing the pressure inside the battery casing 50, the start-up time of the pressure reduction device 110 can be set to approximately 300 seconds or more.

[0088] The above provides various descriptions of the technology disclosed herein. Unless otherwise specified, the embodiments listed herein are not intended to limit the invention. Furthermore, the technology disclosed herein is capable of various modifications, and the constituent elements and processes mentioned herein can be appropriately omitted or combined without causing particular problems.

[0089] In the above embodiments, the charging step S20 is also used for initial charging, but is not limited to this method. The charging step S20 may also be incorporated into additional charging after initial charging to pre-generate gas from the electrode surface. In the above embodiments, the through-hole 55 is an injection hole for injecting non-aqueous electrolyte, but is not limited to this method. The through-hole 55 may also be a hole provided in the battery casing outside the injection hole. In this case, depressurization within the battery casing 50 can be performed while the injection hole is blocked.

[0090] In addition, this specification includes the disclosures described below.

[0091] Item 1: A method for manufacturing a non-aqueous electrolyte secondary battery, comprising:

[0092] A process for obtaining a battery assembly in which electrode bodies including a positive electrode and a negative electrode and a non-aqueous electrolyte are housed in a battery casing having through holes;

[0093] A charging process for charging the battery assembly; and

[0094] Following the charging process, a sealing process is performed to seal the through hole using a sealing member.

[0095] In the charging process, charging is performed under charging conditions where the temperature of the gas inside the battery casing rises.

[0096] The sealing process is performed while maintaining the temperature rise inside the battery casing.

[0097] After the sealing process, the temperature inside the battery casing decreases, resulting in the contraction of the battery casing and / or a reduction in internal pressure due to the contraction of the gas inside the battery casing.

[0098] Item 2:

[0099] In the manufacturing method of the non-aqueous electrolyte secondary battery described in item 1, the pressure inside the battery casing is reduced between the charging step and the sealing step.

[0100] Item 3:

[0101] In the method for manufacturing a non-aqueous electrolyte secondary battery as described in item 1 or 2, the battery casing is depressurized during the charging process.

[0102] Item 4:

[0103] In any one of the methods for manufacturing a non-aqueous electrolyte secondary battery according to items 1 to 3, the charging step is performed in such a way that the temperature of the gas inside the battery casing reaches 35°C or higher.

[0104] Item 5:

[0105] In the method of manufacturing a non-aqueous electrolyte secondary battery according to any one of items 1 to 4, in the sealing step, the through hole of the battery casing is sealed by the sealing member before the temperature of the gas inside the battery casing drops by more than 2°C from the highest temperature of the gas inside the battery casing in the charging step.

[0106] Item 6:

[0107] In the method of manufacturing a non-aqueous electrolyte secondary battery according to any one of items 1 to 5, a plurality of said electrode bodies are housed in the battery casing.

Claims

1. A method for manufacturing a non-aqueous electrolyte secondary battery, characterized in that, include: A process for obtaining a battery assembly in which electrode bodies including a positive electrode and a negative electrode and a non-aqueous electrolyte are housed in a battery casing having through holes; A charging process for charging the battery assembly; and Following the charging process, a sealing process is performed to seal the through hole using a sealing member. In the charging process, charging is performed under charging conditions where the temperature of the gas inside the battery casing rises. The sealing process is performed while maintaining the temperature rise inside the battery casing. After the sealing process, the temperature inside the battery casing decreases, resulting in the contraction of the battery casing and / or a reduction in internal pressure due to the contraction of the gas inside the battery casing.

2. The method for manufacturing a non-aqueous electrolyte secondary battery according to claim 1, wherein, Between the charging process and the sealing process, the pressure inside the battery casing is reduced.

3. The method for manufacturing a non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein, During the charging process, the pressure inside the battery casing is reduced.

4. The method for manufacturing a non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein, In the charging process, the battery is charged in such a way that the temperature of the gas inside the battery casing reaches 35°C or higher.

5. The method for manufacturing a non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein, In the sealing process, the through hole of the battery housing is sealed by the sealing member before the temperature of the gas inside the battery housing drops by more than 2°C from the highest temperature of the gas inside the battery housing during the charging process.

6. The method for manufacturing a non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein, The battery casing houses a plurality of the electrode bodies.

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