JP7238372B2 - Method for manufacturing secondary battery - Google Patents

Method for manufacturing secondary battery Download PDF

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JP7238372B2
JP7238372B2 JP2018229804A JP2018229804A JP7238372B2 JP 7238372 B2 JP7238372 B2 JP 7238372B2 JP 2018229804 A JP2018229804 A JP 2018229804A JP 2018229804 A JP2018229804 A JP 2018229804A JP 7238372 B2 JP7238372 B2 JP 7238372B2
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battery
separator
positive electrode
temporary
temporary battery
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JP2020092049A (en
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裕貴 西川
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Toyota Boshoku Corp
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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Description

本発明は、例えばリチウムイオン電池などの二次電池の製造方法に関する。 The present invention relates to a method of manufacturing a secondary battery such as a lithium ion battery.

従来、この種の二次電池の製造方法として、例えば特許文献１に示すものが知られている。こうした二次電池の製造方法は、正極と負極とが合成樹脂製のセパレータを介して交互に複数積層されてなる電極積層体及び電解液をラミネートフィルムによって形成された外装体で封止して仮電池を形成する工程と、仮電池を加圧した状態で充電する工程と、充電した仮電池を高温環境下でエージングする工程とを備えている。 Conventionally, as a method for manufacturing this type of secondary battery, for example, the method disclosed in Patent Document 1 is known. In the manufacturing method of such a secondary battery, an electrode laminate in which a plurality of positive and negative electrodes are alternately laminated via a synthetic resin separator and an electrolytic solution are temporarily sealed with an outer package formed of a laminated film. It comprises a step of forming a battery, a step of charging the temporary battery under pressure, and a step of aging the charged temporary battery in a high temperature environment.

この場合、仮電池を形成する工程では、電池性能を確保するべく電極の表面に被膜（SEI（Solid Electrolyte Interphase））を形成するために、電極とセパレータとをできるだけ密着させることが好ましい。このため、仮電池の充電は、加圧により電極とセパレータとを密着させた状態で行われる。 In this case, in the step of forming the temporary battery, it is preferable to bring the electrode and the separator into close contact as much as possible in order to form a film (SEI (Solid Electrolyte Interphase)) on the surface of the electrode to ensure battery performance. Therefore, charging of the temporary battery is performed in a state in which the electrode and the separator are brought into close contact with each other by pressurization.

特開２０１４－７１９７５号公報JP 2014-71975 A

ところで、上述のような二次電池の製造方法では、高温環境下で仮電池のエージングを行って被膜の形成を促進するべくエージング中においても仮電池の加圧を継続して行っている。このため、セパレータが特に熱によってクリープ変形してしまうので、セパレータの空隙率が低下する。この結果、リチウムイオンなどの陽イオンがセパレータを透過し難くなる、すなわち電気抵抗が増加するので、二次電池の出力が低下するという問題がある。 By the way, in the manufacturing method of the secondary battery as described above, the temporary battery is aged in a high-temperature environment, and the temporary battery is continuously pressurized even during the aging in order to promote the formation of the film. As a result, the separator is subject to creep deformation due to heat, and the porosity of the separator is reduced. As a result, it becomes difficult for cations such as lithium ions to permeate the separator, that is, the electrical resistance increases, so there is a problem that the output of the secondary battery decreases.

本発明は、このような従来技術に存在する問題点に着目してなされた。その目的は、二次電池の出力が低下することを抑制できる二次電池の製造方法を提供することにある。 The present invention has been made by paying attention to such problems existing in the prior art. It is an object of the present invention to provide a secondary battery manufacturing method capable of suppressing a decrease in output of the secondary battery.

以下、上記課題を解決するための手段及びその作用効果について記載する。
上記課題を解決する二次電池の製造方法は、正極板と負極板とが合成樹脂製のセパレータを介して交互に複数積層されてなる電極積層体及び電解液を、可撓性を有した外装体によって封止して仮電池を形成する仮電池形成工程と、前記仮電池形成工程で形成した前記仮電池を加圧した状態で充電する充電工程と、前記充電工程で充電した前記仮電池を高温環境下でエージングする高温エージング工程と、を備えた二次電池の製造方法であって、前記高温エージング工程のうちの少なくとも一部では、前記仮電池を前記充電工程での加圧力よりも低い加圧力で加圧するか又は前記仮電池を加圧しないことを要旨とする。 Means for solving the above problems and their effects will be described below.
A method of manufacturing a secondary battery for solving the above-mentioned problems is to provide an electrode laminate in which a plurality of positive electrode plates and negative electrode plates are alternately laminated with synthetic resin separators interposed therebetween, and an electrolytic solution, which are provided in a flexible exterior. A temporary battery forming step of forming a temporary battery by sealing with a body, a charging step of charging the temporary battery formed in the temporary battery forming step in a pressurized state, and the temporary battery charged in the charging step and a high temperature aging step of aging in a high temperature environment, wherein in at least part of the high temperature aging step, the temporary battery is subjected to a pressure lower than that in the charging step. The gist is that the temporary battery is pressurized with a pressurizing force or is not pressurized.

この構成によれば、高温エージング工程におけるセパレータのクリープ変形が抑制されるので、セパレータの空隙率の低下を抑制できる。したがって、二次電池の出力が低下することを抑制できる。 According to this configuration, the creep deformation of the separator in the high-temperature aging process is suppressed, so the decrease in the porosity of the separator can be suppressed. Therefore, it is possible to suppress the decrease in output of the secondary battery.

本発明によれば、二次電池の出力が低下することを抑制できる。 ADVANTAGE OF THE INVENTION According to this invention, it can suppress that the output of a secondary battery falls.

一実施形態における二次電池の斜視図。1 is a perspective view of a secondary battery in one embodiment; FIG. 二次電池の製造工程を示すフローチャート。4 is a flow chart showing a manufacturing process of a secondary battery; 電極積層体の分解斜視図。FIG. 2 is an exploded perspective view of an electrode laminate; 電極積層体の斜視図。The perspective view of an electrode laminated body. 仮電池の平面模式図。The plane schematic diagram of a temporary battery. 仮電池を加圧するときの状態を示す断面模式図。FIG. 4 is a schematic cross-sectional view showing a state in which the temporary battery is pressurized. 仮電池の予備室を切除するときの状態を示す平面模式図。FIG. 4 is a schematic plan view showing a state in which a preliminary chamber of a temporary battery is removed; 実施例１及び比較例１～３の仕様を示す表。A table showing specifications of Example 1 and Comparative Examples 1 to 3. 実施例１及び比較例１～３の二次電池において、（ａ）は厚みを比較するグラフ、（ｂ）は初期容量を比較するグラフ、（ｃ）は初期出力を比較するグラフ。4A is a graph for comparing thicknesses, (b) is a graph for comparing initial capacities, and (c) is a graph for comparing initial outputs of the secondary batteries of Example 1 and Comparative Examples 1 to 3. FIG.

以下、二次電池の一実施形態を図面に従って説明する。
図１に示すように、例えばリチウムイオン電池などによって構成される二次電池１１は、矩形状をなす可撓性を有した外装体１２と、外装体１２内に封止された電極積層体１３及び電解液と、外装体１２から露出する正極端子１４及び負極端子１５とを備えている。そして、二次電池１１は、図２に示した第１～第９工程を行うことによって製造される。 An embodiment of a secondary battery will be described below with reference to the drawings.
As shown in FIG. 1 , a secondary battery 11 made of, for example, a lithium ion battery includes a rectangular flexible exterior body 12 and an electrode laminate 13 sealed within the exterior body 12 . and an electrolytic solution, and a positive electrode terminal 14 and a negative electrode terminal 15 exposed from the exterior body 12 . The secondary battery 11 is manufactured by performing the first to ninth steps shown in FIG.

次に、二次電池１１の製造方法について説明する。
二次電池１１を製造する場合には、まず、図３及び図４に示すように、矩形状の正極板１６と、正極板１６よりも一回り大きい矩形状の負極板１７とを、山折りと谷折りを交互に繰り返すつづら折りされた帯状のセパレータ１８を介して、交互に複数積層させることによって電極積層体１３を形成する（第１工程）。 Next, a method for manufacturing the secondary battery 11 will be described.
When manufacturing the secondary battery 11, first, as shown in FIGS. A plurality of electrode laminates 13 are formed by alternately stacking a plurality of strip-shaped separators 18 that are zigzag-shaped and valley-folded alternately (first step).

この場合、セパレータ１８の一方側の対向する面同士の間に正極板１６をそれぞれ挟み、他方側の対向する面同士の間に負極板１７をそれぞれ挟む。セパレータ１８は、絶縁性を有する合成樹脂製の不織布によって構成されている。セパレータ１８における隣り合う２つの折り目間の矩形板状の部分は、負極板１７よりも一回り大きくなっている。本実施形態のセパレータ１８は、空隙率が８０％に設定されている。 In this case, the positive electrode plate 16 is sandwiched between the opposing surfaces on one side of the separator 18, and the negative electrode plate 17 is sandwiched between the opposing surfaces on the other side. The separator 18 is composed of an insulating synthetic resin nonwoven fabric. A rectangular plate-like portion between two adjacent folds of the separator 18 is slightly larger than the negative electrode plate 17 . The separator 18 of this embodiment has a porosity of 80%.

正極板１６は、例えば厚さが１０～２０μｍのアルミニウム箔などの導電性材料によって構成される正極集電体１９と、正極集電体１９の両面または片面に塗布された正極活物質とを有している。正極活物質は、例えばリチウムイオンなどの陽イオンを吸蔵及び放出可能な材料によって構成される。 The positive electrode plate 16 has a positive electrode current collector 19 made of a conductive material such as an aluminum foil having a thickness of 10 to 20 μm, and a positive electrode active material applied to both or one side of the positive electrode current collector 19. are doing. The positive electrode active material is composed of a material capable of intercalating and deintercalating cations such as lithium ions.

正極集電体１９は、略矩形板状をなしており、その長手方向の一端部から突出する矩形板状の正極タブ部２０を有している。すなわち、正極タブ部２０は、正極集電体１９と一体形成されており、セパレータ１８から露出するように突出している。各正極タブ部２０は、正極端子１４（図１参照）に電気的に接続する。正極タブ部２０には、正極活物質を塗布しない。 The positive electrode current collector 19 has a substantially rectangular plate shape, and has a rectangular plate-like positive electrode tab portion 20 protruding from one end portion in the longitudinal direction thereof. That is, the positive electrode tab portion 20 is integrally formed with the positive electrode current collector 19 and protrudes so as to be exposed from the separator 18 . Each positive tab portion 20 is electrically connected to a positive terminal 14 (see FIG. 1). No positive electrode active material is applied to the positive electrode tab portion 20 .

負極板１７は、例えば厚さが１０～２０μｍの銅箔などの導電性材料によって構成される負極集電体２１と、負極集電体２１の両面または片面に塗布された負極活物質とを有している。負極活物質は、例えばリチウムイオンなどの陽イオンを吸蔵及び放出可能な材料によって構成される。負極集電体２１は、略矩形板状をなしており、その長手方向の一端部から突出する矩形板状の負極タブ部２２を有している。 The negative electrode plate 17 has a negative electrode current collector 21 made of a conductive material such as copper foil having a thickness of 10 to 20 μm, and a negative electrode active material applied to both sides or one side of the negative electrode current collector 21 . are doing. The negative electrode active material is composed of a material capable of intercalating and deintercalating cations such as lithium ions. The negative electrode current collector 21 has a substantially rectangular plate shape, and has a rectangular plate-like negative electrode tab portion 22 protruding from one end portion in the longitudinal direction thereof.

すなわち、負極タブ部２２は、負極集電体２１と一体形成されており、セパレータ１８から露出するように突出している。この場合、負極タブ部２２は、正極タブ部２０側とは反対側の方向に突出している。各負極タブ部２２は、負極端子１５（図１参照）に電気的に接続する。負極タブ部２２には、負極活物質を塗布しない。 That is, the negative electrode tab portion 22 is integrally formed with the negative electrode current collector 21 and protrudes so as to be exposed from the separator 18 . In this case, the negative electrode tab portion 22 protrudes in the direction opposite to the positive electrode tab portion 20 side. Each negative tab portion 22 is electrically connected to the negative terminal 15 (see FIG. 1). No negative electrode active material is applied to the negative electrode tab portion 22 .

続いて、図５に示すように、例えばアルミニウムを用いた一対の矩形状をなす可撓性のラミネートフィルムの周縁部同士を溶着することによって形成された外装体１２内に電極積層体１３を挿入する（第２工程）。このとき、正極端子１４及び負極端子１５を外装体１２から露出させるとともに、外装体１２を構成する一対のラミネートフィルムの周縁部同士の一部に溶着しない非溶着部（図示略）を形成する。なお、図５における網掛け部分は、一対のラミネートフィルム同士の溶着部分を示している。 Subsequently, as shown in FIG. 5, the electrode laminate 13 is inserted into the exterior body 12 formed by welding the peripheral edges of a pair of rectangular flexible laminate films made of aluminum, for example. (2nd step). At this time, the positive electrode terminal 14 and the negative electrode terminal 15 are exposed from the outer package 12, and a non-welded portion (not shown) is formed at a part of the peripheral edge portions of the pair of laminate films constituting the outer package 12. In addition, the shaded portion in FIG. 5 indicates the welded portion between the pair of laminate films.

続いて、この非溶着部（図示略）から外装体１２内に、例えば非水系溶媒に電解質を溶解した電解液を注入する（第３工程）。続いて、非溶着部（図示略）を溶着して外装体１２を仮封止することにより、仮電池２３を形成する（第４工程）。すなわち、電極積層体１３及び電解液を外装体１２内に仮封止した仮電池２３を形成する。仮封止された外装体１２は、電極積層体１３を十二分に余裕を持って収容する大きさになっている。本実施形態では、上述した第１～第４工程によって仮電池形成工程が構成される。 Subsequently, an electrolytic solution obtained by dissolving an electrolyte in a non-aqueous solvent, for example, is injected into the exterior body 12 from the non-welded portion (not shown) (third step). Subsequently, the temporary battery 23 is formed by temporarily sealing the exterior body 12 by welding a non-welded portion (not shown) (fourth step). That is, the temporary battery 23 is formed by temporarily sealing the electrode laminate 13 and the electrolytic solution in the exterior body 12 . The temporarily sealed exterior body 12 is sized to accommodate the electrode laminate 13 with a sufficient margin. In the present embodiment, the temporary battery forming process is composed of the first to fourth processes described above.

続いて、図６に示すように、仮電池２３を一対の加圧板２４によって挟むことによって加圧した状態で充電する（第５工程（充電工程））。この場合、一対の加圧板２４同士は、仮電池２３に一定の加圧力が付与されるように、ボルト２５とナット２６とによって一定の距離を維持した状態で締結されている。このため、セパレータ１８と正極板１６とが均一に接触し、且つセパレータ１８と負極板１７とが均一に接触する。そして、この第５工程により、負極板１７の表面に被膜（SEI（Solid Electrolyte Interphase））が形成される。 Subsequently, as shown in FIG. 6, the temporary battery 23 is charged while being pressurized by being sandwiched between a pair of pressure plates 24 (fifth step (charging step)). In this case, the pair of pressurizing plates 24 are fastened together with a constant distance maintained by bolts 25 and nuts 26 so that a constant pressurizing force is applied to the temporary battery 23 . Therefore, the separator 18 and the positive plate 16 are in uniform contact, and the separator 18 and the negative plate 17 are in uniform contact. A film (SEI (Solid Electrolyte Interphase)) is formed on the surface of the negative electrode plate 17 by the fifth step.

続いて、一対の加圧板２４による仮電池２３の加圧を解除した後、仮電池２３を非加圧状態で高温環境下（例えば５０～７０℃程度）において所定時間（例えば数時間～数十時間）だけエージング（放置）する（第６工程（高温エージング工程））。この第６工程では、開始から終了までの全過程にわたって仮電池２３には加圧力が付与されないので、セパレータ１８にも加圧力が付与されない。 Subsequently, after the pressure applied to the temporary battery 23 by the pair of pressure plates 24 is released, the temporary battery 23 is placed in a high temperature environment (for example, about 50 to 70° C.) for a predetermined time (for example, several hours to several tens of hours) in a non-pressurized state. time) (sixth step (high temperature aging step)). In the sixth step, pressure is not applied to the temporary battery 23 throughout the entire process from start to finish, so pressure is not applied to the separator 18 either.

したがって、高温でクリープ変形が生じやすい不織布によって構成されたセパレータ１８であっても、そのクリープ変形が抑制される。そして、この第６工程により、負極板１７の表面での被膜の形成が促進される。なお、この第６工程では、負極板１７の表面に被膜が形成されるときの化学反応によりガスが発生する。 Therefore, even if the separator 18 is made of a non-woven fabric that tends to undergo creep deformation at high temperatures, the creep deformation is suppressed. Formation of the film on the surface of the negative electrode plate 17 is promoted by this sixth step. In the sixth step, gas is generated due to a chemical reaction when the film is formed on the surface of the negative electrode plate 17 .

続いて、仮電池２３を常温環境下で放電させる（第７工程）。この第７工程では、仮電池２３を加圧していてもよいし、仮電池２３の加圧を解除していてもよい。続いて、図７に示すように、仮電池２３の外装体１２を構成する一対のラミネートフィルム同士を本封止部２７において溶着することにより、外装体１２を本封止する（第８工程）。これにより、外装体１２内は、本封止部２７によって、電極積層体１３を収容した収容室２８と、第６工程で発生したガスなどが溜まった予備室２９とに隔絶される。なお、図７における網掛け部分は、一対のラミネートフィルム同士の溶着部分を示している。 Subsequently, the temporary battery 23 is discharged under normal temperature (seventh step). In this seventh step, the provisional battery 23 may be pressurized, or the provisional battery 23 may be depressurized. Subsequently, as shown in FIG. 7, a pair of laminate films forming the exterior body 12 of the temporary battery 23 are welded together at the final sealing portion 27 to permanently seal the exterior body 12 (eighth step). . As a result, the interior of the exterior body 12 is isolated by the main sealing portion 27 into a storage chamber 28 that stores the electrode laminate 13 and a preliminary chamber 29 that stores gas generated in the sixth step. The shaded portion in FIG. 7 indicates the welded portion between the pair of laminate films.

続いて、図７に示すように、第８工程で仮電池２３の外装体１２に形成された予備室２９が切除されるように、切断線Ｓにおいて外装体１２を切断する（第９工程）。これにより、図１に示す二次電池１１が得られる。 Subsequently, as shown in FIG. 7, the exterior body 12 is cut along the cutting line S so that the preliminary chamber 29 formed in the exterior body 12 of the temporary battery 23 in the eighth step is cut (ninth step). . Thereby, the secondary battery 11 shown in FIG. 1 is obtained.

次に、実施例及び比較例について説明する。
（実施例１）
上記実施形態の方法で製造した二次電池１１を実施例１とした。 Next, examples and comparative examples will be described.
(Example 1)
The secondary battery 11 manufactured by the method of the above embodiment was taken as Example 1.

（比較例１）
上記実施形態の方法において、仮電池２３を加圧した状態で第６工程（高温エージング工程）を行って製造した二次電池を比較例１とした。 (Comparative example 1)
Comparative Example 1 was a secondary battery manufactured by performing the sixth step (high-temperature aging step) while the temporary battery 23 was pressurized in the method of the above-described embodiment.

（比較例２）
上記実施形態の方法において、セパレータ１８を微多孔膜（合成樹脂製の膜に細孔を多数形成したもの）に変更し、仮電池を加圧した状態で第６工程行って製造した二次電池を比較例２とした。なお、微多孔膜の空隙率は４０％とした。 (Comparative example 2)
In the method of the above embodiment, a secondary battery manufactured by changing the separator 18 to a microporous film (synthetic resin film with many pores) and performing the sixth step while the temporary battery is pressurized. was used as Comparative Example 2. The porosity of the microporous membrane was set to 40%.

（比較例３）
上記実施形態の方法において、仮電池２３を加圧しない状態で第５工程（充電工程）を行って製造した二次電池を比較例３とした。 (Comparative Example 3)
Comparative Example 3 was a secondary battery manufactured by performing the fifth step (charging step) in the method of the above-described embodiment without pressurizing the temporary battery 23 .

上記した実施例１及び比較例１～３の仕様を図８の表に示す。
＜厚みの測定＞
実施例１及び比較例１～３の厚みを測定し、結果を図９（ａ）のグラフに示した。図９（ａ）から、比較例１は、第６工程（高温エージング工程）によってセパレータ１８がクリープ変形し、実施例１に比べて厚みが大幅に薄くなっていることが分かる。このことから、比較例１は、実施例１に比べてセパレータ１８の空隙率が大幅に低下していることが予想される。 The specifications of Example 1 and Comparative Examples 1 to 3 described above are shown in the table of FIG.
<Measurement of thickness>
The thicknesses of Example 1 and Comparative Examples 1 to 3 were measured, and the results are shown in the graph of FIG. 9(a). As can be seen from FIG. 9A, in Comparative Example 1, the separator 18 was subjected to creep deformation in the sixth step (high-temperature aging step), and the thickness was significantly reduced compared to Example 1. FIG. From this, it is expected that the porosity of the separator 18 is significantly lower in Comparative Example 1 than in Example 1.

＜初期容量＞
実施例１及び比較例１～３の初期容量を測定し、結果を図９（ｂ）のグラフに示した。図９（ｂ）のグラフから、比較例３は、実施例１に比べて初期容量が大きく低下していることが分かる。このことから、比較例３は、仮電池２３を加圧しない状態で第５工程（充電工程）を行っているため、セパレータ１８と、正極板１６及び負極板１７との接触状態が実施例１に比べて不均一になっていることが予想される。 <Initial capacity>
The initial capacities of Example 1 and Comparative Examples 1 to 3 were measured, and the results are shown in the graph of FIG. 9(b). From the graph of FIG. 9B, it can be seen that the initial capacity of Comparative Example 3 is significantly lower than that of Example 1. Therefore, in Comparative Example 3, the fifth step (charging step) is performed without pressurizing the temporary battery 23, so the contact state between the separator 18 and the positive electrode plate 16 and the negative electrode plate 17 is the same as in Example 1. expected to be uneven compared to

＜初期出力＞
実施例１及び比較例１～３の初期出力を測定し、結果を図９（ｃ）のグラフに示した。図９（ｃ）のグラフから、比較例３は、実施例１に比べて初期出力が大きく低下していることが分かる。一方、図９（ａ）のグラフ及び図９（ｃ）のグラフから、微多孔膜によって構成されたセパレータを用いた比較例２では、第６工程（高温エージング工程）で加圧しても、実施例１に比べて厚みの低下や著しい初期出力の低下が確認できない。これは、不織布によって構成されたセパレータ１８を用いた実施例１では、第６工程（高温エージング工程）を行う際に加圧しないことによって、初期出力の低下が抑制されることを示唆している。 <Initial output>
The initial outputs of Example 1 and Comparative Examples 1 to 3 were measured, and the results are shown in the graph of FIG. 9(c). From the graph of FIG. 9C, it can be seen that the initial output of Comparative Example 3 is significantly lower than that of Example 1. On the other hand, from the graphs of FIGS. 9(a) and 9(c), in Comparative Example 2 using a separator made of a microporous membrane, even if pressure was applied in the sixth step (high temperature aging step), Compared to Example 1, neither a decrease in thickness nor a significant decrease in initial output can be confirmed. This suggests that in Example 1, in which the separator 18 made of nonwoven fabric is used, the drop in initial output is suppressed by not applying pressure during the sixth step (high-temperature aging step). .

以上詳述した実施形態によれば、次のような効果が発揮される。
（１）二次電池１１の製造方法において、第６工程（高温エージング工程）では、開始から終了までの全過程にわたって仮電池２３を加圧しない。この構成によれば、第６工程（高温エージング工程）における不織布によって構成されたセパレータ１８のクリープ変形が効果的に抑制されるので、セパレータ１８の空隙率の低下を抑制できる。したがって、二次電池１１の出力が低下することを抑制できる。 According to the embodiment detailed above, the following effects are exhibited.
(1) In the method of manufacturing the secondary battery 11, in the sixth step (high temperature aging step), the temporary battery 23 is not pressurized throughout the entire process from start to finish. According to this configuration, the creep deformation of the separator 18 made of the non-woven fabric in the sixth step (high-temperature aging step) is effectively suppressed, so the decrease in the porosity of the separator 18 can be suppressed. Therefore, it is possible to suppress the output of the secondary battery 11 from decreasing.

（２）二次電池１１の製造方法において、セパレータ１８は、不織布によって構成されている。この構成によれば、セパレータ１８を合成樹脂フィルムによって構成する場合に比べて空隙率を格段に高めることができる。 (2) In the method of manufacturing the secondary battery 11, the separator 18 is made of nonwoven fabric. With this configuration, the porosity can be significantly increased compared to the case where the separator 18 is configured with a synthetic resin film.

（変更例）
なお、上記実施形態は次のように変更してもよい。
・第６工程（高温エージング工程）では、必ずしも開始から終了までの全過程にわたって仮電池２３を加圧しないようにする必要はない。例えば、第６工程の全過程のうちの半分の時間だけ仮電池２３を加圧しないようにしてもよいし、第６工程の全過程のうちの３分の１の時間だけ仮電池２３を加圧しないようにしてもよい。 (Change example)
Note that the above embodiment may be modified as follows.
- In the sixth step (high-temperature aging step), it is not necessary to prevent the temporary battery 23 from being pressurized throughout the entire process from start to finish. For example, the temporary battery 23 may not be pressurized for half of the entire process of the sixth step, or the temporary battery 23 may be applied only for one-third of the entire process of the sixth step. You may choose not to apply pressure.

・第６工程（高温エージング工程）では、開始から終了までの全過程にわたって仮電池２３を第５工程（充電工程）での加圧力よりも低い加圧力で加圧するようにしてもよい。
・第６工程（高温エージング工程）では、第６工程の全過程のうちの一部の時間だけ第５工程（充電工程）での加圧力よりも低い加圧力で仮電池２３を加圧するようにし、第６工程の全過程のうちの残りの時間は仮電池２３を加圧しないようにしてもよい。 - In the sixth step (high-temperature aging step), the temporary battery 23 may be pressurized with a pressure lower than that in the fifth step (charging step) throughout the entire process from start to finish.
- In the sixth step (high-temperature aging step), the temporary battery 23 is pressurized with a pressure lower than that in the fifth step (charging step) for a part of the entire process of the sixth step. , the temporary battery 23 may not be pressurized during the remaining time of the entire process of the sixth step.

・セパレータ１８は、必ずしも不織布によって構成する必要はなく、例えば細孔が多数形成された合成樹脂フィルムによって構成してもよい。
・第５工程（充電工程）では、例えばバネなどの弾性部材によって仮電池２３に一定の加圧力が付与されるようにしてもよい。 - The separator 18 does not necessarily have to be made of non-woven fabric, and may be made of, for example, a synthetic resin film in which a large number of pores are formed.
- In the fifth step (charging step), a constant pressure force may be applied to the temporary battery 23 by an elastic member such as a spring.

１１…二次電池、１２…外装体、１３…電極積層体、１６…正極板、１７…負極板、１８…セパレータ、２３…仮電池。 DESCRIPTION OF SYMBOLS 11... Secondary battery, 12... Armor body, 13... Electrode laminated body, 16... Positive electrode plate, 17... Negative electrode plate, 18... Separator, 23... Temporary battery.

Claims (2)

正極板と負極板とが不織布の山折りと谷折りを交互繰り返すつづら折りされた帯状のセパレータを介して交互に複数積層されてなる電極積層体及び電解液を、可撓性を有した外装体によって封止して仮電池を形成する仮電池形成工程と、
前記仮電池形成工程で形成した前記仮電池を加圧した状態で充電する充電工程と、
前記充電工程で充電した前記仮電池を高温環境下でエージングする高温エージング工程と、
を備えた二次電池の製造方法であって、
前記正極板は、導電性材料によって構成される正極集電体と、前記正極集電体の両面または片面に塗布された正極活物質と、を有し、前記正極集電体は、前記正極集電体と一体形成され、前記セパレータから露出するように突出している正極タブ部を有しており、
前記負極板は、導電性材料によって構成される負極集電体と、前記負極集電体の両面または片面に塗布された負極活物質とを有し、前記負極集電体は、前記負極集電体と一体形成され、前記セパレータから露出するように突出している負極タブ部を有しており、
前記充電工程では、前記仮電池を一対の加圧板によって挟むことによって加圧し、前記セパレータと前記正極板を接触させ、且つ前記セパレータと前記負極板とを接触させ、
前記高温エージング工程のうち少なくとも一部では、前記仮電池を前記充電工程での加圧力よりも低い加圧力で加圧するか又は前記仮電池を加圧しないことを特徴とする二次電池の製造方法。 Electrode laminates and electrolytic solutions, in which a plurality of positive electrode plates and negative electrode plates are alternately laminated via a belt-shaped separator made of a non-woven fabric that is alternately zigzag-folded and valley-folded, are covered by a flexible exterior body. A temporary battery forming step of sealing to form a temporary battery;
A charging step of charging the temporary battery formed in the temporary battery forming step in a pressurized state;
A high temperature aging step of aging the temporary battery charged in the charging step in a high temperature environment;
A method for manufacturing a secondary battery comprising
The positive electrode plate includes a positive electrode current collector made of a conductive material and a positive electrode active material coated on one or both sides of the positive electrode current collector. It has a positive electrode tab part integrally formed with an electric body and protruding so as to be exposed from the separator,
The negative electrode plate has a negative current collector made of a conductive material and a negative active material coated on one or both sides of the negative current collector. having a negative electrode tab part that is integrally formed with the body and protrudes so as to be exposed from the separator,
In the charging step, the temporary battery is sandwiched between a pair of pressure plates to pressurize the separator and the positive electrode plate, and the separator and the negative electrode plate are brought into contact,
A method for manufacturing a secondary battery, wherein in at least part of the high-temperature aging step, the temporary battery is pressurized with a pressure lower than that in the charging step, or the temporary battery is not pressurized. . 前記高温エージング工程では、開始から終了までの全過程にわたって前記仮電池を加圧しないことを特徴とする請求項１に記載の二次電池の製造方法。 2. The method of manufacturing a secondary battery according to claim 1, wherein in the high-temperature aging step, the temporary battery is not pressurized throughout the entire process from start to finish.
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