Method for manufacturing non-aqueous electrolyte secondary batteries

Abstract

To suppress the expansion of non-aqueous electrolyte secondary batteries. [Solution] The method for manufacturing a non-aqueous electrolyte secondary battery includes a step S10 for obtaining a battery assembly, a charging step S20, and a sealing step S30. The battery assembly is a battery case having through holes, containing electrode bodies including a positive electrode and a negative electrode, and a non-aqueous electrolyte. In the charging step S20, the battery assembly is charged. In the sealing step S30, after the charging step S20, the through holes are sealed with a sealing member. In the charging step S20, charging is performed under charging conditions that cause the temperature of the gas inside the battery case to rise. The sealing step S30 is performed while maintaining the elevated temperature inside the battery case. After the sealing step S30, the temperature inside the battery case decreases, and the gas inside the battery case contracts, causing the battery case to shrink and / or the internal pressure to decrease.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a non-aqueous electrolyte secondary battery.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2018-163858 discloses a method for manufacturing a rectangular secondary battery. In the manufacturing method disclosed in this publication, after the liquid injection step of injecting a non-aqueous electrolyte solution, a charging step and a gas discharge step are performed. In the charging step, the battery is charged. In the gas discharge step, a part (15% or more) of the gas in the case is discharged from the liquid injection hole to the outside of the battery case.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The inventor of the present invention desires to suppress the expansion of the non-aqueous electrolyte secondary battery.

Means for Solving the Problems

[0005] The method for manufacturing a non-aqueous electrolyte secondary battery disclosed herein includes a step of obtaining a battery assembly, a charging step, and a sealing step. The battery assembly comprises an electrode body including a positive electrode and a negative electrode, and a non-aqueous electrolyte, housed in a battery case having through holes. In the charging step, the battery assembly is charged. In the sealing step, after the charging step, the through holes are sealed with a sealing member. In the charging step, charging is performed under charging conditions that cause the temperature of the gas inside the battery case to rise. The sealing step is performed while maintaining the elevated temperature inside the battery case. After the sealing step, the temperature inside the battery case decreases, causing the contraction of the gas inside the battery case to result in contraction of the battery case and / or a decrease in internal pressure. According to this manufacturing method, expansion of the non-aqueous electrolyte secondary battery after manufacturing is suppressed. [Brief explanation of the drawing]

[0006] [Figure 1] Figure 1 is a flowchart showing a method for manufacturing a non-aqueous electrolyte secondary battery. [Figure 2] Figure 2 is a perspective view of a battery assembly (non-aqueous electrolyte secondary battery) 100. [Figure 3] Figure 3 is a schematic cross-sectional view along the line III-III in Figure 2. [Figure 4] Figure 4 is a schematic diagram of the electrode body 40. [Figure 5] Figure 5 is a perspective view of the electrode body 40. [Figure 6] Figure 6 is a perspective view of the electrode body 40 attached to the lid 54. [Figure 7] Figure 7 is a schematic diagram showing the state of gas G inside the battery case 50. [Figure 8] Figure 8 is a schematic diagram showing the state of gas G inside the battery case 50. [Figure 9] Figure 9 is a flowchart showing a method for manufacturing a non-aqueous electrolyte secondary battery according to another embodiment. [Figure 10] Figure 10 is a cross-sectional view of the battery assembly 100 during the depressurization process S25. [Modes for carrying out the invention]

[0007] Hereinafter, an embodiment of the technology disclosed herein will be described with reference to the drawings. The embodiment described herein is, of course, not intended to particularly limit the present invention. Each drawing is schematic and does not necessarily reflect the actual object. In addition, the same reference numerals are used for members and parts that perform the same function, and redundant explanations are omitted as appropriate. In the following description, the reference numerals L, R, F, Rr, U, and D in the drawings represent left, right, front, back, up, and down, respectively, and the 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 are merely directions for the convenience of explanation and do not limit in any way the installation configuration of the non-aqueous electrolyte secondary battery, etc. In this specification, the notation "A~B" indicating a range shall include not only the meaning of A or greater and B or less, but also the meaning of "greater than A" and "less than B".

[0008] The method for manufacturing a non-aqueous electrolyte secondary battery disclosed herein will be explained below, using the case where the non-aqueous electrolyte secondary battery is a lithium-ion secondary battery as an example.

[0009] <Method for manufacturing non-aqueous electrolyte secondary batteries> Figure 1 is a flowchart illustrating a method for manufacturing a non-aqueous electrolyte secondary battery. As shown in Figure 1, 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.

[0010] <Step S10 to obtain the battery assembly> In step S10, which is the process of obtaining a 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 a battery case 50.

[0011] FIG. 2 is a perspective view of a battery assembly (non-aqueous electrolyte secondary battery) 100. FIG. 3 is a schematic cross-sectional view taken along line III-III in FIG. 2. FIG. 4 is a schematic view of an electrode body 40. FIG. 5 is a perspective view of the electrode body 40. FIG. 6 is a perspective view of the electrode body 40 attached to the lid 54. Note that the non-aqueous electrolyte secondary battery has the same configuration as the battery assembly except that a sealing member 56 is attached.

[0012] 〈Battery Assembly 100〉 As shown in FIG. 3, the battery assembly 100 includes a battery case 50 that houses an electrode body 40 and a non-aqueous electrolyte (not shown). In this specification, the battery assembly 100 is a structure in which the components of a non-aqueous electrolyte secondary battery 100 (hereinafter also simply referred to as "battery") are assembled and a non-aqueous electrolyte solution is injected. Hereinafter, the non-aqueous electrolyte secondary battery and the battery assembly will be described with the same reference numerals. Note that in this specification, the battery assembly 100 is in a configuration before initial charging is performed and before the through hole 55 is sealed after the injection of the non-aqueous electrolyte solution.

[0013] 〈Battery Case 50〉 The battery case 50 (see FIGS. 2 and 3) has a through hole 55. As the battery case 50, conventionally known materials can be used without particular limitation. The battery case 50 is preferably made of, for example, metal. Examples of the material of the battery case 50 include aluminum, aluminum alloy, iron, iron alloy, etc. Although not particularly limited, the battery case 50 is preferably made of aluminum or aluminum alloy. In this embodiment, the battery case 50 is rectangular (cuboid). The battery case 50 has a case body 52 and a lid 54.

[0014] The case body 52 has a bottom wall 52a with a substantially rectangular plane, 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 FIG. 2). An opening 52h is formed in the upper part of the case body 52.

[0015] The lid 54 is a plate-like member that is substantially rectangular in plan view. The lid 54 is a member that closes the opening 52h of the case body 52. The lid 54 is provided with a through hole 55 and a gas discharge valve 57. The through hole 55 is preferably a liquid injection hole provided for injecting a non-aqueous electrolyte (not shown) into the battery case 50. When the injection of the non-aqueous electrolyte 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 in the lid 54, but is not limited to such a form. The through hole 55 may be provided in the case body 52. The gas discharge valve 57 is a thin-walled portion designed to break (open) when a large amount of gas is generated in the battery case 50 and discharge the gas.

[0016] Terminal insertion holes 58 and 59 to which the positive electrode terminal 60 and the negative electrode terminal 65 are respectively attached are formed in the lid 54. The terminal insertion holes 58 and 59 are respectively formed at the ends in the long side direction Y of the lid 54.

[0017] The positive electrode terminal 60 and the negative electrode terminal 65 are respectively attached to the ends of the lid 54 in the long side direction Y of the battery 100. The positive electrode terminal 60 is connected to a plate-like positive electrode external conductive member 62 outside the battery case 50. The negative electrode terminal 65 is connected to a plate-like negative electrode external conductive member 67 outside the battery case 50. The positive electrode external conductive member 62 and the negative electrode external conductive member 67 are connected to other power storage devices and external devices via an external connection member (such as a bus bar).

[0018] A positive electrode first current collecting portion 71 and a negative electrode first current collecting portion 76 are attached to the inner surface of the lid 54. The positive electrode first current collecting portion 71 and the negative electrode first current collecting portion 76 are respectively plate-like conductive members extending along the inner surface of the lid 54. The lower end portion 60c of the positive electrode terminal 60 is connected to the positive electrode first current collecting portion 71. The lower end portion 65c of the negative electrode terminal 65 is connected to the negative electrode first current collecting portion 76.

[0019] The lid 54 is provided with various insulating members to prevent electrical conductivity between the battery case 50 (case body 52, lid 54) and the electrode terminals (positive electrode terminal 60, negative electrode terminal 65). Gaskets 90 are fitted to the terminal insertion holes 58 and 59 of the lid 54 to prevent electrical conductivity between the electrode terminals and the lid 54. An external insulating member 92 is positioned between the positive electrode external conductive member 62 (or negative electrode external conductive member 67) and the outer surface of the lid 54. An internal insulating member 94 is positioned between the positive electrode first current collector 71 (or negative electrode first current collector 76) and the inner surface of the lid 54. The internal insulating member 94 includes a plate-shaped base portion 94a attached to the inner surface of the lid 54. The internal insulating member 94 includes a protruding portion 94b that extends from the base portion 94a toward the electrode body 40. The protruding portion 94b restricts the vertical movement of the electrode body 40 and prevents direct contact between the electrode body 40 and the lid 54. The material of the insulating member described above is not particularly limited as long as it has the required insulating properties. As the insulating member, synthetic resin materials such as polyolefin resins and fluororesins can be used.

[0020] The cover 54 is attached to the top of the case body 52 with the electrode body 40 attached via the positive electrode current collector 70 and the negative electrode current collector 75, and seals the opening 52h.

[0021] <Electrode body 40> As shown in Figure 4, the electrode body 40 is a flat electrode body in which a strip-shaped positive electrode 10 and a strip-shaped negative electrode 20 are wound around a strip-shaped separator 30. In this embodiment, the electrode body 40 is a so-called wound electrode body. However, it is not limited to this form, and the electrode body 40 may also be a laminated electrode body in which a plurality of positive electrodes and negative electrodes are alternately stacked with separators in between.

[0022] <Positive electrode 10> The positive electrode 10 is a long, strip-shaped member. The positive electrode 10 comprises a positive electrode core 12, which is a foil-shaped metal member, and a positive electrode active material layer 14 formed on the surface of the positive electrode core 12. From the viewpoint of battery performance, it is preferable that the positive electrode active material layer 14 is formed on both sides of the positive electrode core 12. A positive electrode tab 12t is provided on one side edge of the positive electrode 10, protruding outward in the Y direction (left side in Figure 4). Multiple positive electrode tabs 12t are provided at predetermined intervals along the longitudinal direction of the positive electrode 10. These positive electrode tabs 12t are regions where the positive electrode active material layer 14 and protective layer 16 are not formed, and the positive electrode core 12 is exposed. A metal material having a predetermined conductivity is preferably used as the positive electrode core 12. The positive electrode core 12 is preferably made of, for example, aluminum or an aluminum alloy.

[0023] The positive electrode active material layer 14 is a layer containing a positive electrode active material. The positive electrode active material is a material that can reversibly absorb and release charge carriers in relation to the negative electrode active material, which will be described later. The positive electrode active material is not particularly limited. For example, a lithium transition metal composite oxide is preferably used as the positive electrode active material.

[0024] The positive electrode active material layer 14 may 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.

[0025] A protective layer 16 may be provided on one side edge of the positive electrode 10, if necessary. The protective layer 16 is configured to have lower electrical conductivity than the positive electrode active material layer 14. The protective layer 16 is provided on the positive electrode core 12 at a position facing the negative electrode active material layer 24 via a separator 30. The configuration of the protective layer 16 is not particularly limited, but for example, it may be a layer coated with resin, or a layer containing inorganic particles or a binder.

[0026] <Negative electrode 20> The negative electrode 20 is a long, strip-shaped member. The negative electrode 20 comprises a negative electrode core 22, which is a foil-shaped metal member, and a negative electrode active material layer 24 formed on the surface of the negative electrode core 22. From the viewpoint of battery performance, it is preferable that the negative electrode active material layer 24 is formed on both sides of the negative electrode core 22. A negative electrode tab 22t is provided on one side edge of the negative electrode 20, projecting outward in the Y direction (to the right in Figure 4). The negative electrode tab 22t projects in the opposite direction to the positive electrode tab 12t described above. Multiple negative electrode tabs 22t are provided at predetermined intervals along the longitudinal direction of the negative electrode 20. These negative electrode tabs 22t are regions where the negative electrode active material layer 24 is not formed and the negative electrode core 22 is exposed. A metal material having a predetermined conductivity is preferably used as the negative electrode core 22. The negative electrode core 22 is preferably made of, for example, copper or a copper alloy.

[0027] The negative electrode active material layer 24 is a layer containing a negative electrode active material. The negative electrode active material is a material that can reversibly absorb and release charge carriers in relation to the positive electrode active material. The negative electrode active material is not particularly limited. For example, carbon materials, silicon-based materials, and mixed oxides thereof are preferably used as negative electrode active materials. As carbon materials, for example, graphite, hard carbon, soft carbon, amorphous carbon, etc. can be used. As silicon-based materials, silicon, silicon oxide (silica), etc. are examples.

[0028] The negative electrode active material layer 24 may 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 include styrene-butadiene rubber (SBR), carboxymethylcellulose (CMC), polyacrylic acid (PAA), etc. The negative electrode active material layer 24 preferably contains a conductive material. As the conductive material, carbon materials such as acetylene black (AB) and carbon nanotubes can be preferably used.

[0029] <Separator 30> The separator 30 is a long, strip-shaped member that prevents contact between the positive electrode 10 and the negative electrode 20, while also allowing the charge carrier to pass through. The width of the separator 30 can be set to a dimension that can 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.

[0030] The separator 30 is preferably a porous membrane made of resin, having multiple fine pores through which the charge carrier can pass. Examples of the separator 30 include porous sheets (films) made of resins such as polyethylene (PE), polyolefins such as polypropylene (PP), and polyamides. Such porous sheets 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).

[0031] A heat-resistant layer may be formed on the resin sheet constituting the separator 30. The heat-resistant layer is a layer with excellent heat resistance. Preferably, the heat-resistant layer contains ceramic particles and a binder. As the ceramic particles, for example, alumina can be used.

[0032] The separator 30 may 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. A resin material may be used as the adhesive layer. The adhesive layer may include a binder such as polyvinylidene fluoride. The adhesive layer may also include ceramic particles.

[0033] A group of positive electrode tabs 42 and a group of negative electrode tabs 44 protrude from the electrode body 40 along the winding axis WL direction. The group of positive electrode tabs 42 and the group of negative electrode tabs 44 each protrude from different sides in opposite directions. As shown in Figure 5, a second positive electrode current collector 72 and a second negative electrode current collector 77 are connected to the group of positive electrode tabs 42 and the group of negative electrode tabs 44, respectively. As shown in Figure 6, the group of positive electrode tabs 42 is bent and connected to the cover 54 via a first positive electrode current collector 71 and a second positive electrode current collector 72. Similarly, the group of negative electrode tabs 44 is bent and connected to the cover 54 via a first negative electrode current collector 76 and a second negative electrode current collector 77. The first positive electrode current collector 71 and the second positive electrode current collector 72 constitute the positive electrode current collector 70, and the first negative electrode current collector 76 and the second negative electrode current collector 77 constitute the negative electrode current collector 75. In this embodiment, multiple (3) electrode bodies 40 are housed in the case body 52 (see Figure 3) with the lid 54 attached. The number of electrode bodies 40 housed in the battery case 50 is not particularly limited.

[0034] As shown in Figure 2, after the electrode body 40 is placed inside, the periphery of the lid 54 is attached to the top of the case body 52, and the opening 52h of the case body 52 (see Figure 3) is sealed. The lid 54 can be attached to the top of the case body 52, for example, by laser welding. After the opening 52h is sealed, a non-aqueous electrolyte is poured through the through hole 55 of the battery case 50.

[0035] <Non-aqueous electrolyte> As the non-aqueous electrolyte, any conventionally known electrolyte used in secondary batteries can be used without particular limitation. The non-aqueous electrolyte may be a non-aqueous solvent in which a supporting salt is dissolved. As the non-aqueous solvent, carbonate-based solvents such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate can be used. As the supporting salt, fluorine-containing lithium salts such as LiPF6 can be used. The non-aqueous electrolyte may contain various additives as needed, such as gas generators, film-forming agents, dispersants, and thickeners.

[0036] The injection of the non-aqueous electrolyte can be carried out under a predetermined atmosphere. Although not shown in the diagram, the injection of the non-aqueous electrolyte can also be carried out under reduced pressure. For example, the non-aqueous electrolyte can be injected into the battery case 50 inside a vacuum chamber. A vacuum pump for reducing the pressure inside the chamber may be connected to the chamber.

[0037] First, the battery case 50 is placed in the chamber. Next, the chamber is adjusted to a predetermined reduced pressure state. Then, with an injection nozzle (not shown) inserted into the through hole 55 (see Figure 3) of the battery case 50, the non-aqueous electrolyte is injected. Once the non-aqueous electrolyte is injected into the battery case 50, it begins to impregnate the electrode body 40. Injecting the non-aqueous electrolyte under reduced pressure conditions makes it easier for the non-aqueous electrolyte to impregnate the electrode body 40. As a result, the time required for the impregnation of the electrode body 40 with the non-aqueous electrolyte may be shortened. The atmosphere during injection is not particularly limited. The chamber may be configured to allow the introduction of an inert gas such as nitrogen or air.

[0038] After the non-aqueous electrolyte is poured into the battery assembly 100, initial charging is then performed.

[0039] <Charging process S20> In the charging process S20 (see Figure 1), the battery assembly 100 is charged. Preferably, the charging process is an initial charge (degassing charge) to generate gas from the electrode (negative electrode) surface beforehand. The charging process can be carried out under predetermined charging conditions.

[0040] The charging conditions are set such that the temperature of the gas inside the battery case 50 rises. In this embodiment, initial charging is performed at room temperature of about 25°C (for example, 20°C to 30°C). Initial charging is performed in a nitrogen gas atmosphere. During charging, the electrode body 40 and other components inside the battery case 50 may generate heat. This causes the temperature of the gas inside the battery case 50 to rise. In this embodiment, the charging conditions are set so that the temperature of the gas inside the battery case 50 is 35°C or higher. The charging conditions may also be set so that the temperature of the gas inside the battery case 50 is 40°C or higher. However, from the viewpoint of battery performance, an upper limit may be set for the temperature of the gas inside the battery case 50. The upper limit for the temperature of the gas inside the battery case 50 may be set to 60°C or 55°C, for example. Setting such charging conditions makes it easier to seal the through-hole 55 in the sealing process S30 (see Figure 1) described later, while the temperature inside the battery case 50 is high.

[0041] The temperature inside the battery case 50 during charging is not limited to the temperatures described above. The temperature inside the battery case 50 during charging may be determined according to the temperature of the environment in which the battery is expected to be used. For example, the temperature inside the battery case 50 during charging may be set to be 10°C or more higher than the temperature of the environment in which the battery is expected to be used. In this embodiment, the temperature inside the battery case 50 during charging is set to 35°C, which is 10°C or more higher than the ambient temperature of 25°C in which the battery 100 is expected to be used.

[0042] The method for obtaining the temperature of the gas inside the battery case 50 is not particularly limited. The temperature of the gas inside the battery case 50 may be obtained from the temperature of the battery case 50. For example, the relationship between the temperature of the gas inside the battery case 50 and the temperature of the battery case 50 may be determined in advance, as follows: First, a test battery assembly with the desired configuration is prepared. The test battery assembly is charged under the charging conditions for initial charging. The temperature of the gas inside the battery case and the temperature of the battery case are obtained during charging. Based on the relationship between the temperature of the gas inside the battery case and the temperature of the battery case obtained by the test, the temperature inside the battery case 50 may be estimated. Alternatively, the temperature of the gas inside the battery case 50 may be measured directly by a temperature sensor (such as a thermocouple). For example, a small opening may be formed in the battery case 50, and a thermocouple may be inserted through the opening so as not to contact the electrode body 40. The opening may then be closed, and the temperature inside the battery case 50 may be obtained by the thermocouple.

[0043] The battery assembly 100 may be charged with a constant current of 60A or more (so-called CC charging). By charging the battery assembly 100 with a constant current, voltage adjustment becomes unnecessary, and the time required for initial charging can be shortened. In addition, it is easier to calculate the amount of charge charged during initial charging and to adjust the amount of charge during subsequent charging. From the viewpoint of raising the temperature of the battery assembly 100 in a short time, a higher charging current is preferable. Although not particularly limited, the charging current is preferably 60A or more, more preferably 80A or more, and may be 100A or more. Although not particularly limited, the charging current may be set to 300A or less.

[0044] Charging of the battery assembly 100 may be continued until the State of Charge (SOC) reaches a predetermined capacity or the terminal voltage reaches a predetermined voltage value. The SOC and terminal voltage values ​​may be appropriately determined depending on the type of battery 100, etc. The charging time may be 600 seconds or more. Although not particularly limited, the charging time is preferably 300 seconds or more, and may be 900 seconds or more. From the viewpoint of production efficiency, it is preferable that the charging time is not too long. Although not particularly limited, the charging time is 60 minutes or less, and may be, for example, 30 minutes or less.

[0045] Initial charging may be performed in a single charge or in multiple stages (not particularly limited, but approximately 2 to 5 stages). If initial charging is performed in multiple stages, the average charging current during the charging time may be set to 60A or higher. Furthermore, initial charging does not necessarily have to be performed with the constant current described above. Initial charging may be performed using so-called CC-CV charging, where charging is performed initially with a constant current, and then with a constant voltage once a predetermined voltage is reached. Charging conditions should be set appropriately according to the type and dimensions of the battery 100.

[0046] From the viewpoint of facilitating the release of gas from within the battery case 50, it is preferable that the through-hole 55 be left open during the charging process.

[0047] <Sealing process S30> In sealing step S30 (see Figure 1), the through hole 55 is sealed with a sealing member 56. Sealing step S30 is performed while maintaining a elevated temperature inside the battery case 50. Sealing step S30 may be performed under atmospheric pressure (standard atmospheric pressure). Sealing step S30 may be performed at room temperature or at a temperature higher than room temperature. The method of sealing the through hole 55 with the sealing member 56 is not particularly limited. For example, a blind rivet or the like may be used as the sealing member 56.

[0048] In the sealing process S30, the through-hole 55 is sealed while the temperature of the gas inside the battery case 50 is kept from dropping below the highest temperature of the gas inside the battery case 50 in the charging process S20. The through-hole 55 is sealed while the temperature inside the battery case 50 is higher than room temperature. It is preferable that the through-hole 55 be sealed immediately after charging is complete so as not to lower the temperature inside the battery case 50 as much as possible. The through-hole 55 may be sealed before the temperature drops below a predetermined level from the highest temperature of the gas inside the battery case 50 in the charging process S20. It is preferable that the through-hole 55 be sealed by the sealing member 56 before the temperature drops by 2°C or more from the highest temperature of the gas inside the battery case 50 in the charging process S20, and more preferably before it drops by 1°C or more. It is preferable that the sealing process S30 is performed immediately after the charging process S20. This makes it easier for the temperature difference inside the battery case 50 to become large between the time the through-hole 55 is sealed and when the battery 100 is in use.

[0049] After sealing the through-hole 55, aging and other processes are performed using known methods to manufacture the non-aqueous electrolyte secondary battery 100.

[0050] Incidentally, non-aqueous electrolyte secondary batteries can gradually expand due to repeated charging and discharging during long-term use. When non-aqueous electrolyte secondary batteries expand, the space in which they are placed can be compressed. Furthermore, in cases where the aim is to increase capacity, multiple non-aqueous electrolyte secondary batteries may be arranged in one direction (for example, along the shorter side) and used in a constrained manner. In this case as well, if multiple non-aqueous electrolyte secondary batteries expand, the space in which they are placed can be further compressed.

[0051] In the manufacturing method described above, the through-hole 55 of the non-aqueous electrolyte secondary battery 100 is sealed when the temperature inside the battery case 50 is higher than room temperature. Therefore, after the sealing process S30, the temperature inside the battery case 50 decreases, and the gas inside the battery case 50 contracts. This causes shrinkage of the battery case 50 and / or a decrease in internal pressure. The shrinkage of the battery case 50 and the decrease in internal pressure will be explained below.

[0052] After the through-hole 55 is sealed while the temperature inside the battery case 50 is higher than room temperature, the battery 100 is placed in a room temperature environment and its temperature decreases. Figures 7 and 8 are schematic diagrams showing the state of gas G inside the battery case 50. In Figures 7 and 8, components other than the battery case 50 and electrode body 40 are omitted. Figures 7 and 8 schematically show the internal pressure inside the battery case 50 before and after the temperature decrease. Here, the form when the internal pressure is low is shown by a lower hatching density. Figure 7 is a schematic diagram when there is a gap A between the electrode body 40 and the first side wall 52b when the through-hole 55 is sealed. Figure 8 is a schematic diagram when there is no gap between the electrode body 40 and the first side wall 52b when the through-hole 55 is sealed. Note that Figures 7 and 8 merely schematically explain the cases in which the battery case 50 deforms and the internal pressure changes before and after the temperature decrease, and it is not necessarily the case that only one of these events occurs.

[0053] As the temperature of the battery 100 decreases, the gas G inside the battery case 50 attempts to contract. As shown in Figure 7, if there is a gap A between the electrode body 40 and the first side wall 52b, the battery case 50 may deform as the gas G contracts, causing the gap A to narrow (in other words, the distance between the pair of first side walls 52b to narrow). This makes it easier to reduce the thickness of the battery 100. Furthermore, if the electrode body 40 and the first side wall 52b come into contact due to the deformation of the battery case 50, the internal pressure of the battery case 50 may decrease as the temperature drops further.

[0054] As shown in Figure 8, if there is no gap between the electrode body 40 and the first side wall 52b (or if the gap between the electrode body 40 and the first side wall 52b disappears due to the contraction of the battery case 50), the battery case 50 is less likely to deform even if the gas G contracts. Therefore, the volume of gas G is less likely to deform. Instead, the internal pressure of gas G may decrease. Due to the pressure difference between the inside and outside of the battery case 50, expansion of the battery case 50 due to an increase in internal pressure becomes less likely.

[0055] The higher the temperature inside the battery case 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 case 50, the temperature inside the battery case 50 is kept high, and the above-mentioned effect can be achieved. Furthermore, the larger the electrode body 40 is relative to the spatial volume inside the battery case 50, the greater the above-mentioned effect can be.

[0056] Furthermore, the effect of suppressing the expansion of the battery case 50 is more effective the less gas is inside the battery case 50. The smaller the internal volume of the battery case 50 after the non-aqueous electrolyte is injected, relative to the volume of the empty battery case 50, the greater the deformation and internal pressure drop of the battery case 50 described above may be. For example, the internal volume of the battery case 50 after the non-aqueous electrolyte is injected is 50 cm³. 3 The following is preferable. The internal volume of the battery case 50 refers to the volume obtained by subtracting the components provided inside the battery case 50, such as the electrode body 40 and non-aqueous electrolyte, from the volume of the empty battery case 50. Furthermore, it is preferable that the internal volume of the battery case 50 is 10% or less of the volume of the empty battery case 50. In this embodiment, the dimensions of the battery case 50 are approximately 30 mm in the short side direction X, approximately 308 mm in the long side direction Y, and 90 mm in the height direction Z. The internal volume of the battery case 50 is 42.1 cm³. 3 The volume of space inside the battery case 50 relative to the volume of the empty battery case 50 is 5.1%. When a gap A is provided between the electrode body 40 and the first side wall 52b, the dimensions of the gap A are preferably 15 mm or less on one side (for example, 30 mm or less in total on both sides).

[0057] In the manufacturing method for non-aqueous electrolyte secondary batteries described above, the temperature difference before and after charging and sealing causes shrinkage of the battery case and / or a decrease in internal pressure. With this manufacturing method, it is possible to cause shrinkage of the battery case and / or a decrease in internal pressure without contact. Furthermore, no additional equipment is required to deform the battery case or reduce the internal pressure. For example, processing to directly restrain the battery case is not required. As a result, the equipment configuration is simplified, and the cost of non-aqueous electrolyte secondary batteries can be reduced.

[0058] In the embodiment described above, the sealing process S30 is performed after the charging process S20. Other processes may be added in addition to the charging process S20 and the sealing process S30.

[0059] Figure 9 is a flowchart showing a method for manufacturing a non-aqueous electrolyte secondary battery according to another embodiment. Figure 10 is a cross-sectional view of the battery assembly 100 in the depressurization step S25. As shown in Figure 9, the method for manufacturing a non-aqueous electrolyte secondary battery may include the depressurization step S25. Note that the steps for obtaining the battery assembly S10, charging S20, and sealing S30 are the same as in the embodiments described above, so their explanation is omitted.

[0060] In this embodiment, a depressurization step S25 is performed between the charging step S20 and the sealing step S30 to reduce the pressure inside the battery case 50. In the depressurization step S25, as shown in Figure 10, the nozzle 111 of the depressurization device 110 is inserted into the through hole 55. For example, a vacuum pump can be used as the depressurization device 110. The gas inside the battery case 50 is sucked out through the nozzle 111. This reduces the amount of gas inside the battery case 50. As a result, the internal pressure of the battery case 50 decreases more easily after the sealing step S30, and the expansion of the battery case 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. The inside of the battery case 50 is depressurized with the outer circumferential surface of the tip of the nozzle 111 in close contact with the inner circumferential surface of the through hole 55. By depressurizing the inside of the battery case 50 with the nozzle 111 in close contact with the through hole 55, it becomes more difficult for gas to flow into the battery case 50. As a result, the depressurization efficiency can be improved. Furthermore, because the tip of the nozzle 111 is not deeply inserted into the battery case 50, the electrode body 40 and other components housed inside the battery case 50 are less likely to be damaged. Note that the method of reducing pressure inside the battery case 50 is not limited to this configuration.

[0061] In this embodiment, the inside of the battery case 50 is depressurized by a nozzle 111 inserted through the through hole 55. In this configuration, there is no need to move the battery assembly 100 to equipment dedicated to depressurization. The depressurization process S25 can be performed immediately after the charging process S20. Therefore, it is easier to perform the depressurization process S25 while the temperature inside the battery case 50 remains high. The temperature inside the battery case 50 is also more likely to remain high when the through hole 55 is sealed (sealing process S30). As a result, it is easier to cause shrinkage of the battery case 50 and / or a decrease in internal pressure.

[0062] The charging process S20 and the depressurization process S25 may be performed simultaneously. In other words, the depressurization process S25 may be incorporated into the charging process S20. The timing for starting the depressurization inside the battery case 50 is not particularly limited. By performing the charging process S20 and the depressurization process S25 simultaneously, the depressurization time can be extended. This reduces the amount of gas inside the battery case 50 more. As a result, contraction of the battery case 50 and / or a decrease in internal pressure become more likely.

[0063] The depressurization process S25 may be started before the start of charging of the battery assembly 100, after the start of charging of the battery assembly 100, or simultaneously with the start of charging of the battery assembly 100.

[0064] It is preferable that the depressurization inside the battery case 50 is terminated in conjunction with the completion of charging of the battery assembly 100. From the viewpoint of maintaining a high temperature inside the battery case 50, it is preferable that the depressurization inside the battery case 50 is terminated before the completion of charging of the battery assembly 100. However, from the viewpoint of reducing gas inside the battery case 50, it is preferable that there is not too much time between the termination of depressurization inside the battery case 50 and the completion of charging of the battery assembly 100. For example, the time difference between the termination of depressurization inside the battery case 50 and the completion of charging of the battery assembly 100 is preferably within 60 seconds, and more preferably within 30 seconds. It is even more preferable that the termination of depressurization inside the battery case 50 and the completion of charging of the battery assembly 100 occur simultaneously.

[0065] The depressurization conditions are not particularly limited, but the output of the depressurization device 110 may be set so that the pressure inside the battery case 50 is approximately 0.0001 to 0.1 atmospheres. In addition, from the viewpoint of sufficiently reducing the pressure inside the battery case 50, the time for the depressurization device 110 to activate may be set to approximately 300 seconds or more.

[0066] The technologies disclosed herein have been described in detail above. Unless otherwise specified, the embodiments and other details mentioned herein do not limit the present invention. Furthermore, the technologies disclosed herein can be modified in various ways, and each component and each process mentioned herein may be omitted or combined as appropriate, unless no particular problems arise.

[0067] In the embodiments described above, the charging process S20 is performed in conjunction with the initial charging, but the system is not limited to this configuration. The charging process S20 may be incorporated into additional charging after the initial charging, which is performed to generate gas from the electrode surface in advance. In the embodiments described above, the through-hole 55 is an injection hole for injecting a non-aqueous electrolyte, but the system is not limited to this configuration. The through-hole 55 may be a hole provided in the battery case separately from the injection hole. In this case, the pressure inside the battery case 50 can be reduced with the injection hole closed.

[0068] Furthermore, this specification includes the disclosures set forth in the following sections.

[0069] Section 1: A step to obtain a battery assembly comprising an electrode body including a positive electrode and a negative electrode, and a non-aqueous electrolyte, housed in a battery case having through holes, A charging step for charging the aforementioned battery assembly, After the charging step, a sealing step is performed in which the through hole is sealed with a sealing member. Includes, In the charging process, charging is performed under charging conditions that cause the temperature of the gas inside the battery case to rise. The sealing process is performed while maintaining the elevated temperature inside the battery case. After the sealing process, the temperature inside the battery case decreases, causing the gas inside the battery case to contract, resulting in contraction of the battery case and / or a decrease in internal pressure. A method for manufacturing a non-aqueous electrolyte secondary battery.

[0070] Section 2: A method for manufacturing a non-aqueous electrolyte secondary battery according to item 1, wherein the inside of the battery case is depressurized between the charging step and the sealing step.

[0071] Section 3: A method for manufacturing a non-aqueous electrolyte secondary battery according to item 1 or 2, wherein the inside of the battery case is depressurized during the charging step.

[0072] Section 4: A method for manufacturing a non-aqueous electrolyte secondary battery according to any one of claims 1 to 3, wherein the charging step is performed such that the temperature of the gas inside the battery case becomes 35°C or higher.

[0073] Section 5: A method for manufacturing a non-aqueous electrolyte secondary battery according to any one of claims 1 to 4, wherein in the sealing step, the through-hole of the battery case is sealed with the sealing member before the temperature of the gas inside the battery case drops by 2°C or more from the highest temperature of the gas inside the battery case during the charging step.

[0074] Item 6: A method for manufacturing a non-aqueous electrolyte secondary battery according to any one of claims 1 to 5, wherein the battery case houses a plurality of the electrode bodies. [Explanation of Symbols]

[0075] 10 positive electrode 12 Positive electrode core 12t positive electrode tab 14 Cathode active material layer 16 Protective layer 20 negative electrode 22 Negative electrode core 22t negative electrode tab 24 Negative electrode active material layer 30 Separators 40 Electrode body 42 Positive electrode tab group 44 Negative electrode tab group 50 Battery Case 52 Case body 52a bottom wall 52b First side wall 52c 2nd side wall 52h opening 54 Lid 55 Through hole 56 Sealing member 57 Gas discharge valve 58, 59 Terminal insertion holes 60 Positive terminal 60c bottom end 62 Positive electrode external conductive material 65 Negative terminal 65c lower end 67 Negative electrode external conductive member 70 Positive electrode current collector 71 Positive electrode first current collector 72 Positive electrode second current collector 75 Negative electrode current collector 76 Negative electrode first current collector 77 Negative electrode second current collector 90 Gasket 92 External insulating material 94 Internal insulating material 94a Base section 94b Protrusion 100 Battery assembly (non-aqueous electrolyte secondary battery) 110 Pressure Reducing Device 111 Nozzles A gap G Gas WL winding shaft

Claims

1. A step to obtain a battery assembly comprising an electrode body including a positive electrode and a negative electrode, and a non-aqueous electrolyte, housed in a battery case having through holes, A charging step for charging the aforementioned battery assembly, After the charging step, a sealing step is performed in which the through hole is sealed with a sealing member. Includes, In the charging process, charging is performed under charging conditions that cause the temperature of the gas inside the battery case to rise. The sealing process is performed while maintaining the elevated temperature inside the battery case. After the sealing process, the temperature inside the battery case decreases, causing the gas inside the battery case to contract, resulting in contraction of the battery case and / or a decrease in internal pressure. A method for manufacturing a non-aqueous electrolyte secondary battery.

2. A method for manufacturing a non-aqueous electrolyte secondary battery according to claim 1, wherein the inside of the battery case is depressurized between the charging step and the sealing step.

3. A method for manufacturing a non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein the inside of the battery case is depressurized during the charging step.

4. The method for manufacturing a non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein the charging step is performed such that the temperature of the gas inside the battery case 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 step, the through-hole of the battery case is sealed with the sealing member before the temperature of the gas inside the battery case drops by 2°C or more from the highest temperature of the gas inside the battery case during the charging step.

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

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