JP2005166487A - Electrolyte injection quantity calculation method, manufacturing method of laminate cell, and lamiante cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolyte injection quantity calculation method capable of calculating an electrolyte injection quantity without excess or deficiency, a manufacturing method for a laminate cell capable of improving battery characteristics, and the laminate cell. <P>SOLUTION: The manufacturing method of the laminate type laminate cell 100 comprising an electrode plate group 101, a laminate film 121 for enclosing and sealing the electrode plate group 101, and a molten salt electrolyte 131 injected into the laminate film 121 comprises an enclosing process for enclosing the electrode plate group 101 with the laminate film 121 while forming an opening 121K; an evacuation process for evacuating the laminate cell 100; an electrolyte injection process for injecting the molten salt electrolyte 131 into the laminate cell 100 through the opening 121K; and a sealing process for sealing the opening 121K in a vacuum state after the electrolyte injection process. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrolyte injection amount calculation method for calculating an injection amount of an electrolyte to be injected into a laminate cell, a laminate cell manufacturing method, and a laminate cell, and more particularly, a laminate cell having a laminated type and into which a molten salt electrolyte is injected. The present invention relates to an electrolyte injection calculation method, a laminate cell manufacturing method, and a laminate cell.

  Conventionally, a laminate cell in which an electrode plate group forms a laminated type is known. For example, there is a laminate cell 900 as schematically shown in FIG. The laminate cell 900 includes an electrode plate group 901 including a positive electrode sheet 903, a negative electrode sheet 907, and a separator sheet 911, a laminate film 921 that wraps and seals the electrode plate group 901, and a molten salt electrolyte 931 injected into the laminate film 921. Prepare. In the electrode plate group 901, a positive electrode sheet 903 and a negative electrode sheet 907 are laminated, and a separator sheet 911 is interposed therebetween. The positive electrode sheet 903 includes a sheet-like positive electrode current collector foil 904 and a porous positive electrode active material layer 905 formed in a layer form on one surface (the lower surface in FIG. 5). Make. The negative electrode sheet 907 includes a sheet-like negative electrode current collector foil 908 and a porous negative electrode active material layer 909 formed in a layer on one surface (the upper surface in FIG. 5). Eggplant. The separator sheet 911 is made of a porous insulator and has a sheet shape.

  Such a laminate cell 900 is generally manufactured as follows. That is, a positive electrode sheet 903, a negative electrode sheet 907, and a separator sheet 911 are prepared, and these are laminated to constitute the electrode plate group 901. Next, the electrode plate group 901 is surrounded by a laminate film 921 with an opening. Thereafter, a predetermined amount of molten salt electrolyte 931 is injected into the laminate film 921 from the opening. After that, if the opening is sealed, a laminate cell 900 can be formed. This is the first manufacturing method according to the prior art.

Moreover, as a manufacturing method of the conventional laminate cell, the manufacturing method of the thin battery disclosed by patent document 1 is mentioned, for example. The following manufacturing method is disclosed in the column of the prior art in Patent Document 1 (see FIGS. 3 and 4 and the description in the column of the prior art). That is, first, the battery element is filled and impregnated with a predetermined amount of electrolyte. Specifically, the electrolyte is filled and impregnated by immersing the battery element in the electrolyte tank containing the electrolyte. At that time, since the amount of electrolyte filling / impregnating the battery element is determined by the immersion time of the battery element, a predetermined amount of electrolyte is filled / impregnated by selection / control of the immersion time. Next, the battery element is positioned, accommodated and mounted in the exterior film body having one end opened. Thereafter, the exterior film body opening is heat-sealed and hermetically sealed. This is the second manufacturing method according to the prior art.
JP 2001-15099 A

However, in the laminate cell 900 manufactured by the first manufacturing method according to the related art, the force for uniformly pressing the electrodes in the stacking direction does not act, so the distance between the electrodes becomes non-uniform. For this reason, only a part of the electrode contributes to charging / discharging. Therefore, the internal resistance increases, and the battery has poor output characteristics and cycle characteristics.
Further, since the laminate cell 900 has structural variations in itself, the molten salt electrolyte 931 to be injected may be too small or too much with respect to the pore volume in the electrode plate group 901. When the molten salt electrolyte 931 is too small with respect to the pore volume in the electrode plate group 901, a state as schematically shown in FIG. 6 is obtained. In this state, only a part of the electrode contributes to charging / discharging, so that the internal resistance increases and the battery has poor output characteristics and cycle characteristics. On the other hand, when the molten salt electrolyte 931 is excessive with respect to the pore volume in the electrode plate group 901, a state as schematically shown in FIG. In this state, since the electrolyte pool 931A is formed by the excessive molten salt electrolyte 931, the distance between the electrodes becomes non-uniform at that portion, and in this case as well, only a part of the electrode contributes to charging / discharging. For this reason, the internal resistance increases, and the battery has poor output characteristics and cycle characteristics.

Further, even when the laminated laminate cell 900 is manufactured based on the second manufacturing method according to the prior art, the force for uniformly pressing the electrodes in the stacking direction does not act, so the distance between the electrodes is not uniform. Become. For this reason, only a part of the electrode contributes to charging / discharging. Therefore, the internal resistance increases, and the battery has poor output characteristics and cycle characteristics.
Moreover, in this manufacturing method, the battery element is impregnated and filled in the battery element by immersing the battery element in the electrolyte for a predetermined time. However, in this case as well, there are variations in the configuration of the battery elements, so that even if a predetermined amount of electrolyte is impregnated and filled, the electrolyte may be too little or too much. Then, as described above, the battery characteristics are inferior.

  The present invention has been made in view of the current situation, and is an electrolyte injection amount calculation method capable of calculating an electrolyte injection amount that is not excessive or insufficient in order to improve battery characteristics, and manufacture of a laminate cell that can improve battery characteristics. It is an object to provide a laminate cell having a good method and battery characteristics.

  The solution is that one or more positive electrode sheets having a positive electrode active material layer formed on a positive electrode current collector foil and one or more negative electrode sheets having a negative electrode current collector foil formed with a negative electrode active material layer are alternately laminated. An electrode plate group in which a separator sheet is interposed between the positive electrode active material layer and the negative electrode active material layer, a laminate film that wraps and seals the electrode plate group, and is injected into the laminate film. An electrolyte injection amount calculation method for calculating an injection amount of the molten salt electrolyte to be injected into a laminated laminate cell comprising the molten salt electrolyte, the electrode plate group being surrounded by the laminate film, A test cell creating step for creating a test laminate cell sealed without vacuum injecting an electrolyte, a cell volume measuring step for measuring the volume of the test laminate cell, and The solid volume of each member was determined from the weight and true density of each member used in the production of the laminate cell for strike, and the pore volume in the electrode plate group calculated from the difference from the volume of the laminate cell for test was calculated as described above. An electrolyte injection amount calculation method comprising: an electrolyte injection amount calculation step for setting a molten salt electrolyte injection amount.

  According to the present invention, prior to manufacture of a laminate cell, a test laminate cell sealed without vacuum injection of a molten salt electrolyte is prepared (test cell creation step), and the volume is measured (cell volume measurement step). Then, the solid volume of each member was determined from the weight and true density of each member used for the production of the test laminate cell, and the pore volume in the electrode plate group calculated from the difference from the volume of the test laminate cell, The injection amount of the molten salt electrolyte is used (electrolyte injection amount calculation step).

  When the electrolyte injection amount is calculated by such a method, an electrolyte injection amount that is not excessive or insufficient with respect to the pore volume in the electrode plate group of the test laminate cell can be obtained. Therefore, for example, when manufacturing a laminate cell having no structural variation with the test laminate cell, such as a laminate cell of the same lot as this test laminate cell, if the laminate cell is manufactured based on this calculated injection amount, A sufficient amount of molten salt electrolyte can be injected with respect to the pore volume in the plate group. Therefore, it is possible to manufacture a laminate cell in which the entire electrode contributes to charge and discharge compared to a conventional laminate cell. That is, a laminate cell having a small internal resistance and excellent battery characteristics such as output characteristics and cycle characteristics can be manufactured.

  Here, in the cell volume measurement step, it is preferable to immerse the test laminate cell in a liquid (for example, in water) and calculate the volume of the test laminate cell based on the increase in the amount of the liquid. This is because the volume of the test laminate cell can be easily and accurately measured by using such a method.

  The positive electrode current collector foil is not particularly limited as long as it is a sheet, and examples of the material include aluminum foil, stainless steel foil, nickel foil, titanium foil, and alloys thereof as appropriate. Available. The negative electrode current collector foil is not particularly limited as long as it is a sheet, and examples of the material include aluminum foil, copper foil, stainless steel foil, nickel foil, titanium foil, and alloys thereof. Etc. can be used as appropriate.

The material and thickness of the positive electrode active material layer are not particularly limited as long as the positive electrode active material layer is formed in layers on the positive electrode current collector foil. Further, the material and thickness of the negative electrode active material layer are not particularly limited as long as the negative electrode active material layer is formed in layers on the negative electrode current collector foil. The positive electrode active material layer and the negative electrode active material layer are appropriately mixed with the positive electrode active material or the negative electrode active material, for example, a conductive agent, a binder, a dispersant, a filler, an ionic conductive agent, a pressure enhancer, and various additives. An active material paste (slurry) may be prepared, and this may be formed by coating and drying the positive electrode current collector foil or the negative electrode current collector foil.
Examples of the positive electrode active material include lithium cobalt composite oxide, lithium nickel composite oxide, lithium cobalt nickel composite oxide, lithium cobalt vanadium composite oxide, lithium cobalt iron composite oxide, lithium manganese composite oxide, and lithium manganese cobalt. Examples include composite oxides, lithium manganese nickel composite oxides, lithium manganese vanadium composite oxides, and lithium manganese iron composite oxides.
Examples of the negative electrode active material include graphite, coke, fired organic polymer, fired mesoface pitch, metal oxide, metal chalcogenide, lithium-containing transition metal oxide, and chalcogenide.
Examples of the conductive agent include graphite, acetylene black, carbon black, ketjen black, and the like.
Examples of the binder include polyacrylic acid, carboxymethyl cellulose, polytetrafluoroethylene, and polyvinylidene fluoride.

  The separator sheet is not particularly limited as long as it has a sheet shape and can separate and insulate the positive electrode sheet and the negative electrode sheet. For example, a microporous film such as polypropylene or polyethylene can be used as appropriate.

  Another solution is that one or more positive electrode sheets having a positive electrode active material layer formed on a positive electrode current collector foil and one or more negative electrode sheets having a negative electrode active material layer formed on a negative electrode current collector foil. An electrode plate group in which separator sheets are interposed between the positive electrode active material layer and the negative electrode active material layer, a laminate film that encloses and seals the electrode plate group, and a laminate film A molten salt electrolyte injected into a laminate-type laminate cell, wherein the electrode plate group is provided with an opening and surrounded by the laminate film, and the laminate after the surrounding step A vacuuming step for evacuating the cell, an electrolyte injection step for injecting the molten salt electrolyte into the laminate cell from the opening in the vacuum state, and a vacuum state after the electrolyte injection step. , Sealing the opening, and a sealing step of sealing the laminate cell, a method for producing a laminated cell with a.

According to the present invention, an electrode plate group is provided with an opening and surrounded by a laminate film (enclosing step), and this is evacuated (evacuating step). And in a vacuum state, molten salt electrolyte is inject | poured in a lamination cell (electrolyte injection process), and an opening part is continuously sealed in a vacuum state (sealing process).
When a laminate cell is manufactured in this way, the inside of the laminate cell becomes negative with respect to the atmospheric pressure (atmospheric pressure) of the surrounding environment, and the positive electrode sheet and the negative electrode sheet are pressed down uniformly in the lamination direction by the atmospheric pressure of the surrounding environment. It is done. For this reason, the distance between electrodes can be kept constant as compared with a conventional laminate cell in which injection and sealing are not performed in a vacuum state. As a result, a laminate cell in which the entire electrode contributes to charging / discharging than the conventional laminate cell is obtained. Therefore, a laminate cell excellent in battery characteristics such as output characteristics and cycle characteristics can be realized.
In the present invention, since the electrolyte is a molten salt electrolyte and non-volatile, the molten salt electrolyte does not volatilize in the process even if injection and sealing are performed in a vacuum state. Therefore, there is also an advantage that the injection amount (filling amount) of the molten salt electrolyte can be accurately defined.

  Conventionally, vacuuming may be performed in the manufacturing process of the laminate cell. However, this is intended for defoaming, and the final opening is sealed under atmospheric pressure. Therefore, the inside of the laminate cell after completion is not in a negative pressure state. On the other hand, in the present invention, since the electrolyte is injected in a vacuum state and sealing is performed in a vacuum state, the laminate cell after completion is in a negative pressure state. As a result, the battery characteristics are improved as described above.

  Furthermore, in the method for manufacturing a laminate cell described above, in the electrolyte injection step, the injection of the molten salt electrolyte calculated by the electrolyte injection amount calculation method is injected into the laminate cell. The method is good.

  According to the present invention, when the molten salt electrolyte is injected into the laminate cell, the electrolyte injection amount calculated by the above-described electrolyte injection amount calculation method is injected. By doing in this way, the molten salt electrolyte of the quantity without excess and deficiency can be inject | poured with respect to the pore volume in the electrode group of a laminate cell. Therefore, it is possible to manufacture a laminate cell in which the entire electrode contributes to charge / discharge more than the conventional laminate cell. Therefore, it is possible to realize a laminate cell that is further excellent in battery characteristics such as output characteristics and cycle characteristics.

  Another solution is that one or more positive electrode sheets having a positive electrode active material layer formed on a positive electrode current collector foil and one or more negative electrode sheets having a negative electrode active material layer formed on a negative electrode current collector foil. An electrode plate group in which separator sheets are interposed between the positive electrode active material layer and the negative electrode active material layer, a laminate film that encloses and seals the electrode plate group, and a laminate film And a molten salt electrolyte injected into the laminate cell, wherein the interior of the laminate cell is maintained at a negative pressure relative to the atmospheric pressure of the surrounding environment.

In the laminate cell of the present invention, the inside of the cell is kept in a negative pressure state relative to the atmospheric pressure (atmospheric pressure) of the surrounding environment. Therefore, the laminate cell is pressed by the atmospheric pressure of the surrounding environment, and the positive electrode sheet and the negative electrode sheet are each pressed uniformly in the stacking direction. For this reason, compared with the conventional laminate cell, the distance between electrodes can be kept constant. Therefore, the whole electrode contributes to charging / discharging rather than the conventional laminate cell. Thereby, a laminate cell excellent in battery characteristics such as output characteristics and cycle characteristics can be realized.
In the laminate cell of the present invention, since the electrolyte is a molten salt electrolyte and is non-volatile, the electrolyte does not volatilize even in a vacuum state during manufacture. Therefore, the electrolyte can be injected in a vacuum state and further sealed in a vacuum state. Therefore, the inside of the cell can be easily brought into a negative pressure state with respect to the atmospheric pressure of the surrounding environment.

  Furthermore, in the above-mentioned laminate cell, when a hole is made in the laminate cell in which both main surfaces are compressed at 1 atm in a vacuum state, the molten salt electrolyte does not ooze out from the hole, and In the vacuum state, when a hole is made in the laminate cell that is immersed in the molten salt electrolyte and both main surfaces are pressed at a pressure equivalent to 1 atm, the molten salt electrolyte is in a state where no air bubbles are generated from the hole. It is preferable to use a laminated cell.

  In the laminate cell of the present invention, in a vacuum state, when a hole is made, for example, with a needle or the like, in a state where both main surfaces are compressed at 1 atm. Molten salt electrolyte is enclosed. Therefore, the molten salt electrolyte is not excessively injected into the pore volume in the electrode plate group. In addition, when this laminate cell is punctured with a needle or the like into a laminate cell that is immersed in a molten salt electrolyte and pressed at a pressure equivalent to 1 atm. The molten salt electrolyte is enclosed in Therefore, the molten salt electrolyte is not excessively injected with respect to the pore volume in the electrode plate group. That is, in this laminate cell, the molten salt electrolyte is injected into the pore volume in the electrode plate group without excess or deficiency. Therefore, in this laminate cell, the entire electrode further contributes to charge / discharge than the conventional laminate cell, and the battery characteristics such as output characteristics and cycle characteristics are further improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the laminate cell 100 of this embodiment will be described. FIG. 1 schematically shows a cross section of the laminate cell 100. The laminate cell 100 includes an electrode plate group 101 including a positive electrode sheet 103, a negative electrode sheet 107, and a separator sheet 111, a laminate film 121 that wraps and seals the electrode plate group 101, and a molten salt electrolyte 131 injected into the laminate film 121. Prepare.

The electrode plate group 101 is configured such that one positive electrode sheet 103 and one negative electrode sheet 107 are laminated, and one separator sheet 111 is interposed therebetween.
The positive electrode sheet 103 has a sheet-like positive electrode current collector foil 104 made of an aluminum foil having a thickness of 15 μm. As shown in FIG. 2, the positive electrode current collector foil 104 is composed of a rectangular coated portion 104A of 50 mm × 70 mm and a rectangular tab welded portion 104B of 10 mm × 10 mm. A porous positive electrode active material layer 105 is formed in a layered manner on one surface (the lower surface in FIG. 1) of the coating portion 104A. As described later, the positive electrode active material layer 105 includes a positive electrode active material (LiCoO ₂ (lithium cobaltate)), a conductive material (carbon black), a binder (binder) (PVdF (polyvinylidene fluoride)), Formed from. On the other hand, a positive electrode tab 113 made of nickel having a width of 4 mm, a length of 50 mm, and a thickness of 0.1 mm is resistance-welded to the tab weld portion 104B of the positive electrode current collector foil 104. Further, a resin film 117 having a modified PP surface is welded to the tab weld 104B. A part of the positive electrode tab 113 extends to the outside from the laminate film 121 for electrical connection with the outside (see FIG. 3).

The negative electrode sheet 107 has a sheet-like negative electrode current collector foil 108 made of an aluminum foil having a thickness of 15 μm. As shown in FIG. 2, the negative electrode current collector foil 108 is composed of a rectangular coated portion 108A of 52 mm × 72 mm and a rectangular tab welded portion 108B of 10 mm × 10 mm. A porous negative electrode active material layer 109 is formed in a layer on one surface (the upper surface in FIG. 1) of the coating part 108A. As described later, the negative electrode active material layer 109 includes a negative electrode active material (Li ₄ Ti ₅ O ₁₂ (lithium titanate)), a conductive material (carbon black), and a binder (binder) (PVdF (polyfluoride). Vinylidene))). On the other hand, a nickel negative electrode tab 115 having a width of 4 mm, a length of 50 mm, and a thickness of 0.1 mm is resistance-welded to the tab weld portion 108B of the negative electrode current collector foil 108. Further, a resin film 119 having a surface modified PP is welded to the tab weld 108B. A part of the negative electrode tab 115 extends to the outside from the laminate film 121 for electrical connection with the outside (see FIG. 3).

  Separator sheet 111 is made of methylcellulose fiber having a porosity of 70%. The film thickness is 30 μm and forms a sheet, and is a rectangular shape in plan view of 54 mm × 74 mm (see FIGS. 1 and 2).

The laminate film 121 is folded in half to form a bag having a sufficiently larger area than the electrode plate group 101, and the remaining three sides are hermetically sealed.
The molten salt electrolyte 131 is obtained by dissolving LiTFSI (lithium trifluorosulfonylimide) at a concentration of 1.25 M in an EMI-TFSI (ethylmethylimidazolium-trifluorosulfonylimide) dissolved salt. 0.3 ml of the molten salt electrolyte 131 is injected into the laminate cell 100. This injection amount corresponds to the pore volume in the electrode plate group 101. That is, the molten salt electrolyte 131 is injected in an amount that is not excessive or insufficient with respect to the pore volume in the electrode plate group 101.

  Unlike the conventional laminate cell, the laminate cell 100 is maintained at a negative pressure with respect to the atmospheric pressure (atmospheric pressure) of the surrounding environment. Therefore, the laminate cell 100 is pressed by the atmospheric pressure of the surrounding environment, and the positive electrode sheet 103 and the negative electrode sheet 107 are each pressed uniformly in the stacking direction. For this reason, compared with the conventional laminate cell, the distance between electrodes can be kept constant. Therefore, the whole electrode contributes to charging / discharging rather than the conventional laminate cell. Thereby, the laminate cell 100 excellent in battery characteristics such as output characteristics and cycle characteristics can be realized.

  Furthermore, when the laminate cell 100 is punctured with a needle or the like in the vacuum cell in a state where both main surfaces are compressed at 1 atm, the molten salt electrolyte 131 does not ooze out from the hole. In the state, the molten salt electrolyte 131 is sealed. Therefore, the molten salt electrolyte 131 is not excessively injected with respect to the pore volume in the electrode plate group 101. Further, when the laminate cell 100 is dipped in the molten salt electrolyte 131 in a vacuum state and both main surfaces are pressed at a pressure equivalent to 1 atm, when a hole is made in the laminate cell 100 with a needle or the like, bubbles are generated from the hole. The molten salt electrolyte 131 is sealed in a state where no spill occurs. Therefore, the molten salt electrolyte 131 is not excessively injected with respect to the pore volume in the electrode plate group 101. That is, in this laminate cell 100, an amount of molten salt electrolyte 131 that is not excessive or insufficient with respect to the pore volume in the electrode plate group 101 is injected. Therefore, the distance between the electrodes can be kept constant as compared with the conventional laminate cell. Therefore, the entire electrode further contributes to charge / discharge than the conventional laminate cell. Thereby, the laminate cell 100 which is further excellent in battery characteristics such as output characteristics and cycle characteristics can be realized.

Next, a method for manufacturing the laminate cell 100 will be described.
Prior to the manufacture of the laminate cell 100, a test laminate cell is prepared, and the injection amount of the molten salt electrolyte 131 to be injected into the laminate cell 100 is determined.
First, the positive electrode sheet 103 and the negative electrode sheet 107 are prepared (see FIGS. 1 and 2).
Specifically, a positive electrode mixture composed of a positive electrode active material, a conductive material, and a binder is dissolved in a solvent to prepare a positive electrode slurry. In this embodiment, 85 wt% of LiCoO ₂ (lithium cobaltate) is used as the positive electrode active material, 10 wt% of carbon black is used as the conductive material, and 5 wt% of PVdF (polyvinylidene fluoride) is used as the binder. It was. Moreover, N-methyl-2-pyrodrine was used as a solvent.
Then, this positive electrode slurry is applied to the positive electrode current collector foil 104 with a constant film thickness using a blade. In the present embodiment, an aluminum foil having a thickness of 15 μm is used for the positive electrode current collector foil 104. And the slurry for positive electrodes was apply | coated so that it might become 6 mg / cm < ² > of fabric weights.
Thereafter, the solvent is removed by drying, and the positive electrode active material layer 105 is formed on the surface of the positive electrode current collector foil 104.

Similarly, a negative electrode mixture composed of a negative electrode active material, a conductive material, and a binder is dissolved in a solvent to prepare a negative electrode slurry. In this embodiment, 85 wt% of Li ₄ Ti ₅ O ₁₂ (lithium titanate) is used as the negative electrode active material, 10 wt% of carbon black is used as the conductive material, and 5 wt% of PVdF (polyvinylidene fluoride) is used as the binder. Electrode composite material. Moreover, N-methyl-2-pyrodrine was used as a solvent.
Thereafter, the negative electrode slurry is applied to the negative electrode current collector foil 108 with a certain film thickness using a blade. In this embodiment, an aluminum foil having a thickness of 15 μm is used for the negative electrode current collector foil 108. And the slurry for negative electrodes was apply | coated so that it might become 8 mg / cm < ² > of fabric weights.
Thereafter, the solvent is removed by drying to form a positive electrode active material layer 109 on the surface of the negative electrode current collector foil 108.

Next, the positive electrode sheet 103 and the negative electrode sheet 107 are cut into predetermined dimensions. In the positive electrode sheet 103, the dimension of the coating part 104A was 50 mm × 70 mm, and the dimension of the tab weld part 104B was 10 mm × 10 mm. Further, in the negative electrode sheet 107, the dimension of the coating part 108A was 52 mm × 72 mm, and the dimension of the tab weld part 108B was 10 mm × 10 mm.
In addition, a separator sheet 111 is prepared and cut into a predetermined size. In the present embodiment, a separator sheet 111 made of methylcellulose fiber and having a film thickness of 30 μm and a porosity of 70% is used. And this was cut | disconnected to 54 mm x 74 mm.

Next, the positive electrode tab 113 is welded to the tab weld portion 104B of the positive electrode sheet 103, and the negative electrode tab 115 is welded to the tab weld portion 108B of the negative electrode sheet 107. In the present embodiment, a positive electrode tab 113 made of nickel having a width of 4 mm, a length of 50 mm, and a thickness of 0.1 mm is resistance-welded to the tab weld portion 104B of the positive electrode sheet 103. Similarly, a negative electrode tab 115 made of nickel having a width of 4 mm, a length of 50 mm, and a thickness of 0.1 mm was resistance-welded to the tab weld portion 108B of the negative electrode sheet 107.
Thereafter, a resin film 117 whose surface layer was modified PP was welded to a part of the tab weld portion 104B of the positive electrode sheet 103 and a part of the positive electrode tab 113. Similarly, a resin film 119 whose surface layer is modified PP was welded to a part of the tab welded portion 108 </ b> B of the negative electrode sheet 107 and a part of the negative electrode tab 115.

  Next, the positive electrode sheet 103 and the negative electrode sheet 107 are laminated so that the positive electrode active material layer 105 and the negative electrode active material layer 109 do not come into contact with each other with the separator sheet 111 interposed therebetween, thereby forming the electrode plate group 101.

  Next, as shown in FIG. 3, the electrode plate group 101 is inserted into a bag made of the laminate film 121, and the electrode plate group 101 is surrounded by the laminate film 121 by providing an opening 121 </ b> K. Specifically, the laminate film 121 is folded in half to form a bag having a sufficiently larger area than the electrode plate group 101. Then, the electrode plate group 101 is inserted into the bag. In that case, it inserts so that the positive electrode tab 113 and the negative electrode tab 115 may be located in the other side (left side in FIG. 3) of a bending part. And after that, one side of the electrode plate group 101 (the lower side in FIG. 3) of the bag-shaped laminate film 121 and the tab 113, 115 side (the left side in FIG. 3) of the electrode plate group 101. Seal the sides with a sealing machine. Thus, an opening 121K is formed on the other side of the electrode plate group 101 (upper side in FIG. 3) in the bag-shaped laminate film 121. Further, the positive electrode tab 113 and the negative electrode tab 115 are sealed in a state of protruding outward from the laminate film 121.

Next, using a vacuum sealing machine, the opening 121K is sealed in a vacuumed state (degree of vacuum: 0.1 Pa) to produce a test laminate cell. That is, a test laminate cell that is vacuum-sealed without injecting the molten salt electrolyte 131 is created (test cell creation step).
Next, the volume of the test laminate cell is measured (cell volume measurement step). Specifically, the test laminate cell is immersed in water, and the volume of the test laminate cell is calculated based on the increase in the liquid amount. In this way, the volume of the test laminate cell can be measured easily and accurately.

Next, the solid volume of each member is obtained from the weight and true density of each member used for the production of the test laminate cell. Each member includes an electrode active material, a conductive material, a binder, current collector foils 104 and 108, a separator sheet 111, a sealant, tabs 113 and 115, a laminate film 121, and the like. Then, the pore volume in the electrode plate group 101 calculated from the difference from the volume of the test laminate cell is set as the injection amount of the molten salt electrolyte 131 (electrolyte injection amount calculation step). In this embodiment, the injection volume was calculated as 0.3 ml.
In this way, the injection amount of the molten salt electrolyte 131 to be injected into the laminate cell 100 is determined.

Next, the laminate cell 100 is actually manufactured.
First, the electrode plate group 101 is configured in the same manner as the above-described production of the test laminate cell. Thereafter, similarly to the production of the test laminate cell, the electrode plate group 101 is surrounded by the laminate film 121 with the opening 121K (enclosing step) (see FIG. 3).

Next, the laminate cell 100 is evacuated as shown in FIG. 4 using a vacuum sealing machine (evacuation step). The degree of vacuum was set to 0.1 Pa, similar to the production of the test laminate cell.
Next, the molten salt electrolyte 131 is injected into the laminate cell 100 from the opening 121K using a microsyringe in a vacuum state (while being put in a vacuum sealing machine) (electrolyte injection step). At that time, the electrolyte injection amount calculated by the electrolyte injection amount calculation method described above is injected into the laminate cell 100. In the present embodiment, a molten salt electrolyte obtained by dissolving LiTFSI (lithium trifluorosulfonylimide) at a concentration of 1.25 M in EMI-TFSI (ethylmethylimidazolium-trifluorosulfonylimide) dissolved salt was used. And 0.3 ml of electrolyte was inject | poured into the lamination cell 100 with the micro syringe.
In this electrolyte injection step, the electrolyte is a non-volatile electrolyte such as the molten salt electrolyte 131. Therefore, even when this electrolyte is injected in a vacuum state, the electrolyte does not volatilize and the volume does not change. Therefore, the electrolyte injection amount can be accurately defined.

Next, in a vacuum state (while being put in a vacuum sealing machine), the opening 121K is sealed, and the laminate cell 100 is sealed (sealing step). Also in this sealing step, since the electrolyte is a non-volatile electrolyte such as the molten salt electrolyte 131, the electrolyte does not volatilize during sealing and no volume change occurs.
In this way, the laminate cell 100 is completed.

  As described above, in the present embodiment, prior to the manufacture of the laminate cell 100, a test laminate cell is created and the electrolyte injection amount to be injected into the laminate cell 100 is calculated. By doing so, it is possible to obtain an electrolyte injection amount that is not excessive or insufficient with respect to the pore volume in the electrode plate group 101 of the test laminate cell. Therefore, when manufacturing the laminate cell 100 having no structural variation with the test laminate cell, such as the laminate cell 100 of the same lot as the test laminate cell, the laminate cell 100 is manufactured based on the calculated injection amount. The molten salt electrolyte 131 can be injected in an amount that is not excessive or insufficient with respect to the pore volume in the electrode plate group 101 of the laminate cell 100. Therefore, the whole electrode contributes to charging / discharging rather than the conventional laminate cell. Thereby, the laminate cell 100 excellent in battery characteristics such as output characteristics and cycle characteristics can be realized.

  Furthermore, in this embodiment, the actual laminate cell 100 is manufactured by performing the surrounding process, the vacuum drawing process, the electrolyte injection process, and the sealing process as described above. If manufactured in this way, the inside of the laminate cell 100 becomes negative with respect to the atmospheric pressure of the surrounding environment, and the positive electrode sheet 103 and the negative electrode sheet 107 are uniformly pressed in the stacking direction by the atmospheric pressure of the surrounding environment. For this reason, the distance between electrodes can be kept constant as compared with a conventional laminate cell in which injection and sealing are not performed in a vacuum state. As a result, the entire electrode further contributes to charge / discharge than the conventional laminate cell. Thereby, the laminate cell 100 which is further excellent in battery characteristics such as output characteristics and cycle characteristics can be realized.

(Survey results)
Next, the battery characteristics of the laminate cell 100 of this example were investigated. For comparison with the laminate cell 100 of this example, three types of laminate cells were prepared (Comparative Examples 1 to 3). The laminate cell of Comparative Example 1 was manufactured by setting the injection amount of the molten salt electrolyte to 0.1 ml, which is extremely smaller than the example (0.3 ml). In addition, the laminate cell of Comparative Example 2 was manufactured by setting the injection amount of the molten salt electrolyte to 0.5 ml, which is extremely larger than the example (0.3 ml). The laminated cell of Comparative Example 3 was manufactured by sealing the molten salt electrolyte at atmospheric pressure without setting the amount of molten salt electrolyte to 0.3 ml as in the example.

In this investigation, after adjusting each laminate cell to DOD 60%, the output was measured by the IV method at −30 ° C. to determine the output density per battery weight.
Specifically, DOD (Depth of Discharge) was adjusted by fully charging for 4 hours at an upper limit voltage at a current value of 1 C, then discharging for 108 minutes at a current value of C / 3, and the DOD was set to 60%.
In the IV measurement, the discharge and charging described below were repeated for the laminate cell with the adjusted DOD, and the voltage after 2 seconds was recorded. Discharging and charging were performed at C / 5 for 10 seconds and then at C / 5 for 10 seconds. Then, after discharging for 10 seconds at C / 3, it was charged for 10 seconds at C / 3. Further, after discharging at C / 2 for 10 seconds, charging was performed at C / 2 for 10 seconds. Furthermore, after discharging at 1C for 10 seconds, charging was performed at 1C for 10 seconds. Furthermore, after discharging at 2C for 10 seconds, it was charged at 2C for 10 seconds. Furthermore, after discharging at 3C for 10 seconds, it was charged at 3C for 10 seconds. Furthermore, after discharging at 5C for 10 seconds, it was charged at 5C for 10 seconds.
Next, each current value and each voltage value measured by IV measurement were blotted to obtain a regression line. Then, the current value when extrapolating the regression line to the lower limit voltage V1 of the battery was I1, and the output was obtained from V1 and I1.

  As a result, the power density of the laminate cell 100 of the example was about 60 W / kg. On the other hand, the laminate cell of Comparative Example 1 had a power density of about 10 W / kg. The laminate cell of Comparative Example 2 had a power density of about 40 W / kg. The laminate cell of Comparative Example 3 had a power density of about 30 W / kg. That is, the laminated cells of Comparative Examples 1 to 3 all had a lower output density than the laminated cell 100 of the example.

  From these results, it can be seen that the output density is good in the laminate cell 100 (Example) in which the inside is maintained in a negative pressure state and the molten salt electrolyte 131 is injected without excess or deficiency. On the other hand, it can be seen that the laminate cell (Comparative Example 1) in which the injection amount of the molten salt electrolyte 131 is extremely small has a poor output density. It can also be seen that the output density is inferior even in a laminate cell (Comparative Example 2) in which the amount of molten salt electrolyte 131 injected is extremely large. It can also be seen that the output density is inferior even in a laminate cell (Comparative Example 3) in which the inside is not maintained in a negative pressure state.

  In this investigation, comparison is made by changing the injection amount of the molten salt electrolyte 131 extremely (Comparative Examples 1 and 2). However, if the difference in the injection amount from the embodiment is reduced, a better output density can be obtained. On the other hand, when the inside is not maintained in a negative pressure state, as described above (Comparative Example 3), even if the molten salt electrolyte 131 is injected without excess or deficiency, the output density is greatly inferior. . Therefore, first of all, it is important to keep the inside of the cell in a negative pressure state. In addition, it is preferable to more accurately define the injection amount of the molten salt electrolyte 131.

In the above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof. .
For example, in the above embodiment, the electrode plate group 101 is configured such that the positive electrode sheet 103 and the negative electrode sheet 107 are stacked one by one, and the separator sheet 111 is interposed therebetween. However, the electrode plate group can be configured by increasing the total number of these sheets 103, 107, and 111. In such a laminate cell, the same effect as described above can be obtained.

It is a schematic diagram which shows the cross section of the laminate cell which concerns on embodiment. It is explanatory drawing which shows the structure of an electrode group regarding the manufacturing method of the laminate cell which concerns on embodiment. It is explanatory drawing which shows a mode that the electrode group was provided with the opening part and it surrounded with the laminate film regarding the manufacturing method of the laminate cell which concerns on embodiment. It is explanatory drawing which shows a mode that the opening part was sealed in the vacuum state regarding the manufacturing method of the laminate cell which concerns on embodiment. It is a schematic diagram which shows the cross section of the laminate cell which concerns on a prior art. It is a schematic diagram which shows a mode that the injection amount of molten salt electrolyte is too small regarding the laminate cell which concerns on a prior art. It is a schematic diagram which shows a mode that the injection amount of molten salt electrolyte is excessive regarding the laminate cell which concerns on a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Laminate cell 101 Electrode group 103 Positive electrode sheet 104 Positive electrode current collection foil 105 Positive electrode active material layer 107 Negative electrode sheet 108 Negative electrode current collection foil 109 Negative electrode active material layer 111 Separator sheet 121 Laminate film 131 Molten salt electrolyte

Claims (5)

One or more positive electrode sheets in which a positive electrode active material layer is formed on the positive electrode current collector foil and one or more negative electrode sheets in which a negative electrode active material layer is formed on the negative electrode current collector foil are alternately laminated, A group of electrode plates each having a separator sheet interposed between the material layer and the negative electrode active material layer;
A laminate film that encloses and seals the electrode plate group;
A molten salt electrolyte injected into the laminate film;
An electrolyte injection amount calculation method for calculating an injection amount of the molten salt electrolyte to be injected into a laminated laminate cell comprising:
A test cell creation step for creating a test laminate cell that surrounds the electrode plate group with the laminate film and is vacuum-sealed without injecting the molten salt electrolyte;
A cell volume measuring step for measuring the volume of the test laminate cell;
Obtain the solid volume of each member from the weight and true density of each member used to create the test laminate cell, and calculate the pore volume in the electrode plate group calculated from the difference from the volume of the test laminate cell. An electrolyte injection amount calculation step for setting the injection amount of the molten salt electrolyte; and
An electrolyte injection amount calculation method comprising: One or more positive electrode sheets in which a positive electrode active material layer is formed on the positive electrode current collector foil and one or more negative electrode sheets in which a negative electrode active material layer is formed on the negative electrode current collector foil are alternately laminated, A group of electrode plates each having a separator sheet interposed between the material layer and the negative electrode active material layer;
A laminate film that encloses and seals the electrode plate group;
A molten salt electrolyte injected into the laminate film;
A method for producing a laminated laminate cell comprising:
An enclosing step of enclosing the electrode plate group with the laminate film by providing an opening;
A vacuuming step of evacuating the laminate cell after the surrounding step;
In a vacuum state, an electrolyte injection step of injecting the molten salt electrolyte into the laminate cell from the opening,
After the electrolyte injection step, in a vacuum state, sealing the opening and sealing the laminate cell,
A method for manufacturing a laminate cell. A method for producing a laminate cell according to claim 2,
A method for manufacturing a laminate cell, wherein, in the electrolyte injection step, the injection amount of the molten salt electrolyte calculated by the electrolyte injection amount calculation method according to claim 1 is injected into the laminate cell. One or more positive electrode sheets in which a positive electrode active material layer is formed on the positive electrode current collector foil and one or more negative electrode sheets in which a negative electrode active material layer is formed on the negative electrode current collector foil are alternately laminated, A group of electrode plates each having a separator sheet interposed between the material layer and the negative electrode active material layer;
A laminate film that encloses and seals the electrode plate group;
A molten salt electrolyte injected into the laminate film;
A laminated laminate cell comprising:
A laminate cell in which the inside of the laminate cell is maintained in a negative pressure state relative to the atmospheric pressure of the surrounding environment. The laminate cell according to claim 4, wherein
In a vacuum state, when a hole is made in the laminate cell in which both main surfaces are compressed at 1 atmosphere, the molten salt electrolyte does not ooze out from the hole, and
In a vacuum state, when a hole is made in the laminate cell that has been immersed in the molten salt electrolyte and pressed on both main surfaces at a pressure equivalent to 1 atm, the molten salt electrolyte is sealed so that no bubbles are generated from the hole. Laminated cell.

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