JP6589258B2 - Method for manufacturing power storage element - Google Patents

Description

  The present invention relates to a power storage element having a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and an electrolyte containing an additive.

  The shift from gasoline cars to electric cars has become important as a global environmental problem. For this reason, use of a nonaqueous electrolyte secondary battery such as a lithium ion secondary battery as a power source for an electric vehicle has been studied. When a non-aqueous electrolyte secondary battery is charged and discharged at a high rate current required for an electric vehicle, the lithium ion concentration in the interlayer electrolyte decreases, the battery resistance value increases, and the output of the lithium ion secondary battery decreases.

  Therefore, conventionally, a technique for suppressing an increase in the battery resistance value of the secondary battery has been proposed (see, for example, Patent Document 1). In Patent Document 1, even if charging / discharging is performed at a high rate of current by increasing the lithium ion concentration of the electrolyte solution in the electrode exposed portion higher than the lithium ion concentration of the interlayer electrolyte solution, the decrease in the lithium ion concentration of the interlayer electrolyte solution is reduced. It is possible to suppress the increase in the battery resistance value.

JP 2010-1113920 A

  In the conventional technique described above, a film forming agent is added to the electrolytic solution for the purpose of promoting permeation of lithium ions and preventing deterioration. A film is formed on the surface of the electrode in the electrode body by impregnating the electrode body constituted by lamination of the positive electrode, the negative electrode, and the separator with the electrolytic solution containing the film forming agent.

  However, even when the free electrolyte present at the bottom of the battery container is sucked upward through the separator during battery operation, a film is formed on the electrode surface, but during this time, the additive decomposes on the negative electrode surface. It will be. For this reason, the additive does not sufficiently reach vertically above the electrode body, and a film distribution occurs on the upper side and the lower side of the electrode body. Due to the distribution of the film, there is a problem in that the electrode body is locally deteriorated to cause variation in durability.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a power storage device in which film formation of an electrode is made uniform and variation in durability is suppressed, and a method for manufacturing the same.

  In order to achieve the above object, an energy storage device according to one embodiment of the present invention includes a positive electrode, a negative electrode, an electrode body including a separator disposed between the positive electrode and the negative electrode, and a film forming agent as an additive. Including an electrolyte solution impregnated in the electrode body, a container for containing the electrode body and the electrolyte solution, and a first end portion that is one of the end portions of the electrode body. The ratio of the film formation amount per unit volume at the second end located on the opposite side of the first end portion to the film formation amount per unit volume is 0.8 or more and 1.2 or less.

  According to this, since the ratio of the film formation amount in the electrode body is 0.8 or more and 1.2 or less, either the first end portion or the second end portion is installed and used on the upper side in the vertical direction. Even in this case, the uniformity of the film distribution in the electrode body is maintained. Therefore, since local deterioration in the electrode body is suppressed, it is possible to suppress variations in durability.

  Furthermore, a positive electrode terminal that is electrically connected to the positive electrode and disposed on the second end side of the container, and is electrically connected to the negative electrode and connected to the second end side of the container. You may decide to provide the negative electrode terminal arrange | positioned.

  According to this, since the ratio of the film formation amount in the electrode body is 0.8 or more and 1.2 or less, either the electrode terminal side end or the opposite side end is installed on the upper side in the vertical direction. Even if it is used, the uniformity of the film distribution in the electrode body is maintained. Therefore, since local deterioration in the electrode body is suppressed, it is possible to suppress variations in durability.

  Furthermore, the positive electrode current collector electrically connected to the positive electrode and disposed on the second end side of the power storage element, and the first negative electrode of the power storage element electrically connected to the negative electrode A negative electrode current collector disposed on an end side; a positive electrode terminal electrically connected to the positive electrode current collector; and a negative electrode terminal electrically connected to the negative electrode current collector. Also good.

  According to this, since the ratio of the film formation amount in the electrode body is 0.8 or more and 1.2 or less, either the positive terminal end or the negative terminal end is installed on the upper side in the vertical direction. Even if it is used, the uniformity of the film distribution in the electrode body is maintained. Therefore, since local deterioration in the electrode body is suppressed, it is possible to suppress variations in durability.

  Further, the power storage element may be configured such that the ratio is 0.8 or more and 1.2 or less in a state where the second end portion is installed in a vertical direction above the first end portion. Good.

  According to this, since the ratio of the film formation amount in the electrode body is 0.8 or more and 1.2 or less, the end portion on the electrode terminal side is on the upper side in the vertical direction than the end portion on the opposite side in use. Even when installed, the uniformity of the coating distribution within the electrode body is maintained. Therefore, since local deterioration in the electrode body is suppressed, it is possible to suppress variations in durability.

  The power storage element is disposed such that the second end portion is on the upper side in the vertical direction with respect to the first end portion, or the first end portion is on the upper side in the vertical direction with respect to the second end portion. In this state, the ratio may be 0.8 or more and 1.2 or less.

  According to this, since the ratio of the film formation amount in the electrode body is 0.8 or more and 1.2 or less, the positive electrode terminal side end is in the vertical direction upper side than the negative electrode terminal end in use. Even when installed, the uniformity of the coating distribution within the electrode body is maintained. Therefore, since local deterioration in the electrode body is suppressed, it is possible to suppress variations in durability.

  The film forming agent may contain sulfur.

  Thereby, the film formation on the electrode surface is promoted, and the decrease in the output can be suppressed by suppressing the decomposition of the electrolytic solution.

  The positive electrode terminal and the negative electrode terminal are disposed on the same surface of the container, and a liquid injection plug for injecting the electrolyte into the container is further provided on the same surface. May be.

  When a liquid injection stopper is provided on the surface on which the positive electrode terminal and the negative electrode terminal are provided, the liquid is injected with the surface facing upward at the time of manufacture. In this case, after the injection, the free electrolyte is present inside the container opposite to the above surface across the electrode body. When a predetermined process such as aging is performed in this state, the ratio of the film formation amount is less than 0.8 at the time of use, and the film distribution becomes non-uniform.

  On the other hand, according to the power storage element, even when the liquid is injected with the surface facing upward, the ratio of the film formation amount is 0.8 or more and 1.2 or less. The uniformity of the film distribution is maintained.

  In addition, a method for manufacturing an energy storage device according to one embodiment of the present invention includes a positive electrode, a negative electrode, and an electrode body having a separator disposed between the positive electrode and the negative electrode, a container that houses the electrode body, A method of manufacturing an electricity storage device comprising a positive electrode terminal and a negative electrode terminal arranged on the same surface of a container, and an injection step of injecting an electrolytic solution containing a film forming agent as an additive into the container from an electrolytic solution injection port And an aging step for sealing the electrolyte solution injection port after the injection step, and aging for impregnating the electrode body with the electrolyte solution to form a film on the surfaces of the positive electrode and the negative electrode In the aging step, the aging is performed by installing the power storage element so that the positive electrode terminal and the negative electrode terminal are arranged at positions other than the upper side in the vertical direction.

  According to this, since the surface of the container in which the positive electrode terminal and the negative electrode terminal are arranged is disposed in a state other than the upper side in the vertical direction, the power storage element is any one of the surface, the positive electrode terminal, and the negative electrode terminal. Even if it is installed and used on the upper side in the vertical direction, the uniformity of the film distribution within the electrode body is maintained. Therefore, since local deterioration in the electrode body is suppressed, it is possible to suppress variations in durability.

  In the injection step, the electrolyte may be injected into the container from the electrolyte injection port provided on the same surface.

  When the electrolyte inlet is provided on the surface, the liquid is injected with the surface facing upward. In this case, after the injection, the free electrolyte is present inside the container opposite to the above surface across the electrode body. When the aging treatment is performed in this installed state, the film formation amount is larger on the opposite side than on the electrode terminal side, and the film distribution becomes non-uniform.

  On the other hand, according to this aspect, at the time of aging treatment, the free electrolyte is not unevenly distributed inside the container on the opposite side. Therefore, the uniformity of the film distribution in the electrode body is realized at the time of use.

  Further, in the aging step, the aging may be performed by installing the power storage element so that the vertical direction of the power storage element is reversed with respect to the use state.

  According to this, since the storage element is disposed and aged so that the vertical direction of the power storage element is reversed with respect to the use state, the uniformity of the film distribution in the electrode body is realized at the time of use.

  Further, in the aging step, the positive electrode terminal side end portion of the electrode body is scheduled to be used with the positive electrode terminal side end portion or the negative electrode terminal side end portion arranged on the upper side in the vertical direction. The aging may be performed by installing the power storage element so as to be on the lower side in the vertical direction than the end portion on the negative electrode terminal side.

  According to this, the additive is reduced and decomposed by the negative electrode current collector connecting the negative electrode and the negative electrode terminal while the free electrolyte present near the end on the positive electrode terminal side is sucked upward during aging. Since it can be prevented, the additive diffuses uniformly. Therefore, the uniformity of the film distribution within the electrode body is ensured between the positive terminal end and the negative terminal end, and the positive terminal end or the negative terminal end is arranged on the upper side in the vertical direction during use. Even in this case, the uniformity of the film distribution in the electrode body is realized.

  According to the electricity storage device and the method for manufacturing the same according to the present invention, the film formation of the electrode is made uniform, so that variations in durability can be suppressed.

It is an external appearance perspective view of the electrical storage element which concerns on Embodiment 1 of this invention. It is sectional drawing at the time of use of the electrical storage element which concerns on Embodiment 1 of this invention. It is sectional drawing at the time of aging of the electrical storage element which concerns on Embodiment 1 of this invention. It is process drawing explaining the manufacturing method of the electrical storage element which concerns on Embodiment 1 of this invention. It is sectional drawing at the time of the 1st use of the electrical storage element which concerns on Embodiment 2 of this invention. It is sectional drawing at the time of the 2nd use of the electrical storage element which concerns on Embodiment 2 of this invention. It is sectional drawing at the time of aging of the electrical storage element which concerns on Embodiment 2 of this invention. It is a block diagram at the time of the 3rd use of the electrical storage element which concerns on Embodiment 2 of this invention. It is process drawing explaining the manufacturing method of the electrical storage element which concerns on Embodiment 2 of this invention.

  Hereinafter, a power storage device according to an embodiment of the present invention will be described with reference to the drawings. Each of the embodiments described below shows a preferred specific example of the present invention. Numerical values, shapes, materials, constituent elements, arrangement positions and connection forms of constituent elements, and the like shown in the following embodiments are merely examples, and are not intended to limit the present invention. In addition, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims indicating the highest concept of the present invention are described as optional constituent elements that constitute a more preferable embodiment.

(Embodiment 1)
First, the structure of the electrical storage element 1 which concerns on Embodiment 1 of this invention is demonstrated.

[1. overall structure]
FIG. 1 is an external perspective view of a power storage device according to Embodiment 1 of the present invention. In addition, the figure is a figure which saw through the container inside.

  The storage element 1 is a secondary battery that can charge and discharge electricity, and more specifically, is a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. For example, the electric storage element 1 is a secondary battery used for a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), an electric vehicle (EV), and the like. In addition, the electrical storage element 1 is not limited to a nonaqueous electrolyte secondary battery, A secondary battery other than a nonaqueous electrolyte secondary battery may be sufficient, and a capacitor may be sufficient as it.

  As shown in the figure, the electricity storage device 1 includes an electrode body 2, a container 3, a positive electrode terminal 4, a negative electrode terminal 5, an electrolytic solution (nonaqueous electrolyte) 6, a positive electrode current collector 7, and a negative electrode current collector. The electric body 8 is provided.

[2. Electrode body]
The electrode body 2 includes a positive electrode, a negative electrode, and a separator, and is a member that can store electricity. Specifically, the electrode body 2 is formed by winding a layered arrangement so that a separator is sandwiched between a negative electrode and a positive electrode so that the whole becomes an oval shape. In the figure, the electrode body 2 has an oval shape, but may be a circular shape or an elliptical shape. Moreover, the shape of the electrode body 2 is not limited to a wound type, and may be a shape (stacked type) in which flat plate plates are stacked.

[2.1 Positive electrode]
The positive electrode has a positive electrode base material layer and a positive electrode mixture layer.

  The positive electrode base material layer is a long belt-shaped conductive current collector foil made of aluminum or an aluminum alloy. Note that as the current collector foil, a known material such as nickel, iron, stainless steel, titanium, baked carbon, a conductive polymer, conductive glass, or an Al—Cd alloy can be used as appropriate.

  The positive electrode mixture layer is an active material layer formed on the surface of the positive electrode base material layer. That is, the positive electrode mixture layer is formed on both surfaces of the positive electrode base material layer. The positive electrode mixture layer includes a positive electrode active material, a conductive additive, and a binder.

As the positive electrode active material used for the positive electrode mixture layer, known compounds can be used without any particular limitation. Among them, Li _a Ni _b M1 _c M2 _d W _x Nb is a positive electrode active material capable of occluding and releasing lithium ions. _y Zr _z O ₂ (where, a, b, c, d, x, y, z are 0 ≦ a ≦ 1.2, 0 ≦ b ≦ 1, 0 ≦ c ≦ 0.5, 0 ≦ d ≦ 0.5, 0 ≦ x ≦ 0.1, 0 ≦ y ≦ 0.1, 0 ≦ z ≦ 0.1, b + c + d = 1 is satisfied, M1 and M2 are Mn, Ti, Cr, Fe, Co , Cu, Zn, Al, Ge, Sn, and Mg, or a compound represented by LiNi _x Mn _y Co _z O ₂ (x + y + z = 1, x <1) , Y <1, z <1) are preferably used.

  The kind in particular of conductive support agent used for a positive mix layer is not restrict | limited, A metal or a nonmetal may be sufficient. As the metal conductive aid, a material composed of a metal element such as copper or nickel can be used. In addition, as the nonmetallic conductive aid, carbon materials such as graphite, carbon black, acetylene black, and ketjen black can be used.

  As the binder used for the positive electrode mixture layer, the type is particularly limited as long as the material is stable with respect to the solvent and the electrolytic solution used at the time of manufacturing the electrode and is stable with respect to the oxidation-reduction reaction at the time of charge and discharge. Not. For example, as a binder, thermoplastic resins such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR) Polymers having rubber elasticity such as fluoro rubber can be used as one kind or a mixture of two or more kinds.

  In addition, the positive electrode may have an undercoat layer between the positive electrode base material layer and the positive electrode mixture layer.

[2.2 Negative electrode]
The negative electrode has a negative electrode base material layer and a negative electrode mixture layer.

  The negative electrode substrate layer is a long strip-shaped conductive current collector foil made of copper or a copper alloy. Note that as the current collector foil, a known material such as nickel, iron, stainless steel, titanium, baked carbon, a conductive polymer, a conductive glass, or an Al—Cd alloy can be used as appropriate.

  The negative electrode mixture layer is an active material layer formed on the surface of the negative electrode substrate layer, and is disposed on both sides of the negative electrode substrate layer so as to sandwich the negative electrode substrate layer. The negative electrode mixture layer includes a negative electrode active material, a conductive additive, and a binder.

As the negative electrode active material used for the negative electrode mixture layer, a known material can be appropriately used as long as it is a negative electrode active material capable of occluding and releasing lithium ions. For example, lithium metal and lithium alloys (lithium metal-containing alloys such as lithium-aluminum, lithium-lead, lithium-tin, lithium-aluminum-tin, lithium-gallium, and wood alloys) and lithium can be occluded / released. Alloys, carbon materials (eg, graphite, non-graphitizable carbon, graphitizable carbon, low-temperature fired carbon, amorphous carbon, etc.), metal oxides, lithium metal oxides (Li ₄ Ti ₆ O ₁₂ etc.), polyphosphate compounds Etc. Among these, non-graphitizable carbon and graphitizable carbon are particularly preferable.

  Since the conductive support agent used for a negative mix layer is the same as the conductive support agent used for a positive mix layer, detailed description is abbreviate | omitted.

  As the binder used for the negative electrode mixture layer, the type of the binder is particularly limited as long as it is stable to the solvent and the electrolytic solution used at the time of manufacturing the electrode and stable to the oxidation-reduction reaction at the time of charge and discharge. Not. For example, thermoplastic resin such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR), fluoro rubber Such polymers having rubber elasticity can be used as one kind or a mixture of two or more kinds.

[2.3 Separator]
The separator is a long strip-shaped separator disposed between the positive electrode and the negative electrode, and the electrode body 2 is formed by being wound in the longitudinal direction together with the positive electrode and the negative electrode and laminating a plurality of layers. The separator includes a separator substrate layer and an inorganic coating layer.

  The separator base material layer is a main body of the separator, and the entire resin porous membrane can be used. For example, as the separator base layer, a resin porous membrane having a woven or non-woven fiber of polymer, natural fiber, hydrocarbon fiber, glass fiber or ceramic fiber is used. The porous resin membrane preferably has woven or non-woven polymer fibers. In particular, the porous resin membrane preferably has a polymer fabric or fleece or is such a fabric or fleece. As polymer fibers, preferably polyacrylonitrile (PAN), polyamide (PA), polyester, such as polyethylene terephthalate (PET) and / or polyolefin (PO), such as polypropylene (PP) or polyethylene (PE) or such polyolefins And non-conductive fibers of a polymer selected from a mixture or composite membrane. The resin porous membrane may be a polyolefin microporous membrane, a nonwoven fabric, paper or the like, and is preferably a polyolefin microporous membrane.

  The inorganic coating layer is a layer provided on at least one surface of the separator base material layer and provided on the separator base material layer. As the inorganic coating layer, it is preferable to use a resin that does not oxidize and become a conductor. Thereby, oxidation of a separator is suppressed and charge / discharge cycle characteristics are improved.

Specifically, the inorganic coating layer is an inorganic layer containing heat-resistant inorganic particles as heat-resistant particles. As the inorganic particles, any of synthetic products and natural products can be used without particular limitation. For example, the inorganic particles are composed of one or more of the following inorganic substances alone or as a mixture or a composite compound. Oxide fine particles such as iron oxide, SiO ₂ , Al ₂ O ₃ , TiO ₂ , BaTiO ₂ , ZrO, alumina-silica composite oxide, nitride fine particles such as aluminum nitride and silicon nitride, calcium fluoride, barium fluoride, Slightly soluble ionic crystal particles such as barium sulfate, covalently bonded crystal particles such as silicon and diamond, clay particles such as talc and montmorillonite, boehmite, zeolite, apatite, kaolin, mullite, spinel, olivine, sericite, bentonite, mica And mineral resource-derived substances such as these or artificial products thereof. Further, the surface of conductive fine particles such as metal fine particles; oxide fine particles such as SnO ₂ and tin-indium oxide (ITO), carbonaceous fine particles such as carbon black and graphite, and the like (for example, a material having electrical insulation properties) Fine particles imparted with electrical insulation properties by surface treatment with the above-described material constituting the electrically insulating inorganic particles) may be used. In particular, as the inorganic _{particles, SiO 2, Al 2 O 3} , alumina - silica composite oxide.

  In addition, although it is preferable that the separator is equipped with the inorganic coating layer, it does not need to be equipped with the inorganic coating layer.

[3. container]
The container 3 has a rectangular cylindrical shape made of metal, and includes a housing main body including a bottom plate 33, a positive electrode side wall 34, and a negative electrode side wall 35, and a metal upper plate 32 that closes an opening of the main body. Has been. In addition, the container 3 can be hermetically sealed by welding the upper plate 32 and the housing body after the electrode body 2 and the like are accommodated therein. The casing body surrounds the electrode body 2 together with the positive electrode side wall 34 and the negative electrode side wall 35 in addition to the bottom plate 33, the positive electrode side wall 34, and the negative electrode side wall 35, and includes two side walls facing each other in the X-axis direction. Contains. The upper plate 32 is provided with a positive electrode terminal 4 and a negative electrode terminal 5, and a liquid injection stopper 31 is provided. In addition, when inject | pouring electrolyte solution into the container 3, the injection stopper 31 is removed and electrolyte solution is inject | poured from an electrolyte solution injection port.

  The container is not limited to a rectangular cylinder made of metal. Any shape may be used as long as the electrode body 2 and the electrolytic solution 6 can be hermetically accommodated. Moreover, the laminate container which consists of resin may be sufficient.

  Further, the positive electrode terminal 4 and the negative electrode terminal 5 are not limited to being arranged on the same surface of the upper plate 32. The positive electrode terminal 4 and the negative electrode terminal 5 may be disposed on either the bottom plate 33 or the side wall, respectively.

[4. Electrode terminal]
The positive electrode terminal 4 is an electrode terminal electrically connected to the positive electrode of the electrode body 2, and the negative electrode terminal 5 is an electrode terminal electrically connected to the negative electrode of the electrode body 2. In other words, the positive electrode terminal 4 and the negative electrode terminal 5 lead the electricity stored in the electrode body 2 to the external space of the power storage element 1, and in order to store the electricity in the electrode body 2, It is an electrode terminal made of metal for introducing. The positive terminal 4 and the negative terminal 5 are disposed on the upper plate 32 so as to face each other in the longitudinal direction.

[5. Current collector]
The positive electrode current collector 7 is disposed between the positive electrode of the electrode body 2 and the positive electrode side wall 34 of the container 3, and has conductivity and rigidity electrically connected to the positive electrode terminal 4 and the positive electrode of the electrode body 2. It is a member. The positive electrode current collector 7 is formed of aluminum, an aluminum alloy, or the like, like the positive electrode base material layer of the electrode body 2.

  The negative electrode current collector 8 is disposed between the negative electrode of the electrode body 2 and the negative electrode side wall 35 of the container 3, and has conductivity and rigidity electrically connected to the negative electrode terminal 5 and the negative electrode of the electrode body 2. It is a member. The negative electrode current collector 8 is formed of copper or a copper alloy as in the negative electrode base material layer of the electrode body 2.

[6. Electrolyte]
As the electrolytic solution 6 sealed in the container 3, those that are generally proposed for use in lithium ion batteries or the like can be used, and various types can be selected. In the electricity storage device 1, the following organic solvent and electrolyte salt are combined and used as a non-aqueous electrolyte. In the container 3, the nonaqueous electrolyte is impregnated in the positive electrode mixture layer, the negative electrode mixture layer, and the separator.

  Examples of organic solvents for non-aqueous electrolytes include cyclic carbonates such as propylene carbonate, ethylene carbonate, butylene carbonate, chloroethylene carbonate, and vinylene carbonate; cyclic esters such as γ-butyrolactone and γ-valerolactone; dimethyl carbonate, diethyl Chain carbonates such as carbonate and ethyl methyl carbonate; chain esters such as methyl formate, methyl acetate and methyl butyrate; tetrahydrofuran or derivatives thereof; 1,3-dioxane, 1,4-dioxane, 1,2-dimethoxyethane Ethers such as 1,4-dibutoxyethane and methyldiglyme; nitriles such as acetonitrile and benzonitrile; dioxolane or derivatives thereof; ethylene sulfide, sulfolane, sultone or derivatives thereof Examples thereof include a conductor alone or a mixture of two or more thereof, but are not limited thereto. In addition, you may add a well-known additive to a nonaqueous electrolyte. In these non-aqueous electrolytes, it is preferable to use a mixture of ethylene carbonate, dimethyl carbonate, and methyl ethyl carbonate because the lithium ion conductivity is maximized.

Examples of the electrolyte salt contained in the nonaqueous electrolyte include LiClO ₄ , LiBF ₄ , LiAsF ₆ , LiPF ₆ , LiSCN, LiBr, LiI, Li ₂ SO ₄ , Li ₂ B ₁₀ Cl ₁₀ , NaClO ₄ , NaI, Inorganic ion salts containing one of lithium (Li), sodium (Na) or potassium (K) such as NaSCN, NaBr, KClO ₄ , KSCN, LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C _{2 F 5 SO 2) 2,} LiN (CF 3 SO 2) (C 4 F 9 SO 2), LiC (CF 3 SO 2) 3, LiC (C 2 F 5 SO 2) 3, (CH 3) 4 NBF ₄ , (CH ₃ ) ₄ NBr, (C ₂ H ₅ ) ₄ NClO ₄ , (C ₂ H ₅ ) ₄ NI, (C ₃ H ₇ ) ₄ NBr, (n− _{C 4 H 9) 4 NClO 4} , (n-C 4 H 9) 4 NI, (C 2 H 5) 4 N-maleate, (C 2 H 5) 4 N-benzoate, (C 2 H 5) 4 N Organic ionic salts such as -phthalate, lithium stearyl sulfonate, lithium octyl sulfonate, lithium dodecylbenzene sulfonate and the like can be mentioned, and these ionic compounds can be used alone or in combination of two or more.

  Here, the electrolytic solution 6 of the electricity storage device 1 of the present invention contains an interface protective film forming agent as an additive for the purpose of promoting the permeation of lithium ions and preventing deterioration due to the film formation on the electrode. The additive is preferably a film forming agent containing sulfur (S) element for forming a film on the surface of the positive and negative electrodes. By containing the film forming agent containing sulfur element in the electrolytic solution 6, film formation on the electrode surface is promoted, and it is possible to suppress degradation of the electrolytic solution and suppress a decrease in output. Examples of the additive include diallyl sulfide, allyl phenyl sulfide, allyl vinyl sulfide, allyl ethyl sulfide, propyl sulfide, diallyl disulfide, allyl ethyl disulfide, allyl propyl disulfide, allyl phenyl disulfide and other sulfides, 1,3-propane sultone, Cyclic sulfonate esters such as 1,4-butane sultone, 1,3-propene sultone, 1,4-butene sultone, methyl methyl disulfonate, ethyl methyl disulfonate, propyl methyl disulfonate, ethyl ethyl disulfonate, propyl ethyl disulfonate Cyclic disulfonates such as bis (vinylsulfonyl) methane, methyl methanesulfonate, ethyl methanesulfonate, propyl methanesulfonate, ethane Methyl phonate, ethyl ethanesulfonate, propyl ethanesulfonate, methyl benzenesulfonate, ethyl benzenesulfonate, propyl benzenesulfonate, phenylmethanesulfonate, phenylethanesulfonate, phenylpropanesulfonate, methyl benzylsulfonate, benzyl Chain sulfonates such as ethyl sulfonate, propyl benzyl sulfonate, benzyl methanesulfonate, benzyl ethanesulfonate, benzyl propanesulfonate, dimethyl sulfite, diethyl sulfite, ethyl methyl sulfite, methyl propyl sulfite, Ethyl propyl sulfite, diphenyl sulfite, methyl phenyl sulfite, ethyl phenyl sulfite, vinyl ethylene sulfite, divinyl ethylene Sulphites such as sulfite, propylene sulfite, vinyl propylene sulfite, butylene sulfite, vinyl butylene sulfite, vinylene sulfite, phenylethylene sulfite, dimethyl sulfate, diethyl sulfate, diisopropyl sulfate, dibutyl sulfate, ethylene glycol sulfate , Propylene glycol sulfate, butylene glycol sulfate, sulfate esters such as pentene glycol sulfate, bistrimethylsilyl sulfate, and the like, but are not limited thereto. In addition, the said additive may use the compound illustrated above individually or in combination of 2 or more types.

  In addition, the said film formation agent is not limited to what contains a sulfur element, For example, you may not contain sulfur, such as lithium difluoro oxalate phosphate (LiFOP). By using LiFOP as an additive, promotion of lithium ion permeation by film formation at the electrode is achieved, and the capacity retention rate against charge / discharge cycles is further improved. When LiFOP or the like is used as an additive, it is assumed that gas is generated by a decomposition reaction other than the film formation when the film is formed on the electrode. In this case, the electrolytic solution 6 may further contain a second additive that does not generate a gas when forming a film on the electrode, or does not cause a battery swelling after the first charge / discharge with a small amount of gas generation. . Examples of the second additive include lithium difluorophosphate, vinylene carbonate, methyl vinylene carbonate, ethyl vinylene carbonate, propyl vinylene carbonate, phenyl vinylene carbonate, vinyl ethylene carbonate, divinyl ethylene carbonate, dimethyl vinylene carbonate, diethyl vinylene carbonate, Carbonates such as fluoroethylene carbonate, vinyl esters such as vinyl acetate and vinyl propionate, diallyl sulfide, allyl phenyl sulfide, allyl vinyl sulfide, allyl ethyl sulfide, propyl sulfide, diallyl disulfide, allyl ethyl disulfide, allyl propyl disulfide, allyl Sulfides such as phenyl disulfide, 1,3-propane Cyclic sulfonates such as ruton, 1,4-butane sultone, 1,3-propene sultone, 1,4-butene sultone, bis (vinylsulfonyl) methane, methyl methanesulfonate, ethyl methanesulfonate, propyl methanesulfonate, Methane ethane sulfonate, ethyl ethane sulfonate, propyl ethane sulfonate, methyl benzene sulfonate, ethyl benzene sulfonate. Propyl benzenesulfonate, phenylmethanesulfonate, phenylethanesulfonate, phenylpropanesulfonate, methyl benzylsulfonate, ethyl benzylsulfonate, benzylsulfonate, benzyl methanesulfonate, benzyl ethanesulfonate, benzyl propanesulfonate, Chain sulfonates such as dimethyl sulfite, diethyl sulfite, ethyl methyl sulfite, methyl propyl sulfite, ethyl propyl sulfite, diphenyl sulfite, methyl phenyl sulfite, ethyl methyl sulfite, vinyl ethylene sulfite , Divinylethylene sulfite, propylene sulfite, vinyl propylene sulfite, butylene sulfite, vinyl butylene sulfite, vinyl Sulfites such as rensulfite and phenylethylene sulfite, sulfate esters such as dimethyl sulfate, diethyl sulfate, diisopropyl sulfate, dibutyl sulfate, ethylene glycol sulfate, propylene glycol sulfate, butylene glycol sulfate, pentene glycol sulfate , Benzene, toluene, xylene, fluorobenzene, biphenyl, cyclohexylbenzene, 2-fluorobiphenyl, 4-fluorobiphenyl, diphenyl ether, tert-butylbenzene, orthoterphenyl, metaterphenyl, naphthalene, fluoronaphthalene, cumene, fluorobenzene, Aromatic compounds such as 2,4-difluoroanisole, halogen-substituted alkanes such as perfluorooctane, tristriborate Chirushiriru, sulfuric bis trimethylsilyl, silyl esters such as phosphoric acid tris trimethylsilyl and the like.

  These compounds can be used alone or in combination of two or more.

[7. Electrode body film formation]
FIG. 2 is a cross-sectional view of the power storage device according to Embodiment 1 of the present invention when in use. As shown in the figure, in the present embodiment, in the electricity storage device 1, the upper plate 32 on which the positive electrode terminal 4 and the negative electrode terminal 5 are disposed is arranged above the bottom plate 33 in the gravitational direction (vertical direction). So that it is installed and used. In this state, the electrode body 2 is impregnated with the electrolytic solution 6 between the positive electrode and the negative electrode. Further, the free electrolyte 60 that is not impregnated inside the electrode body 2 remains inside the bottom plate 33.

  Here, the case of the conventional electrical storage element is demonstrated. When the storage element is left in the state shown in FIG. 2, the free electrolyte remaining in the vicinity of the inside of the bottom plate is sucked up in the direction of the upper plate (vertically upward) through the separator. At this time, the additive is sucked up in the same manner, but the additive is decomposed on the negative electrode having a negative voltage when the power storage element is used. Thereby, the additive concentration is higher on the bottom plate side than on the top plate side, and as a result, the coating distribution is non-uniform.

  On the other hand, in the electrical storage element 1 according to the present embodiment, the upper plate 32 is disposed below the bottom plate 33 in the gravitational direction at the time of manufacture, and an aging process is performed.

  FIG. 3 is a cross-sectional view of the energy storage device according to Embodiment 1 of the present invention during aging. As shown in the figure, in the energy storage device 1 according to the present embodiment, the upper plate 32 on which the positive electrode terminal 4 and the negative electrode terminal 5 are disposed is lower than the bottom plate 33 in the gravity direction in the aging process at the time of manufacture. Placed in. Thereby, the free electrolyte 60 remains in the vicinity of the inside of the upper plate 32 during the period of the aging step. Therefore, after the liquid injection process at the time of manufacture, the upper plate 32 is disposed above the bottom plate 33 in the gravity direction, and has a concentration gradient in which the additive concentration on the bottom plate side is higher than the additive concentration on the upper plate side. Even if it exists, it becomes possible after the said aging process to relieve | moderate the said density | concentration gradient in film formation.

  In the present embodiment, the aging process in the aging step is a process of setting to SOC (State Of Charge) which is 35 ° C. or higher and lower than or equal to the negative electrode potential which is lower than the reductive decomposition potential of the additive. For example, as the aging process, the storage element is arranged so that the upper plate 32 is below the bottom plate 33 in the direction of gravity, and the temperature is set in a 45 ° C. thermostatic chamber in a state where SOC (State Of Charge) is set to 80%. Leave for 15 hours. After passing through this aging step, the first film that is the ratio of the film formation amount per unit volume of the region A on the upper plate 32 side to the film formation amount per unit volume of the region B on the bottom plate 33 side of the electrode body 2 The ratio is 0.8 or more and 1.2 or less. Here, the region B is a first end portion that is one of the end portions of the electrode body 2, and the region A is the first end portion of the end portions of the electrode body 2. It is the 2nd edge part located in the other side. The positive electrode terminal 4 and the negative electrode terminal 5 are both electrode terminals arranged on the second end side of the electricity storage device 1.

  In addition, when not performing the said aging process which concerns on this Embodiment, the said 1st membrane | film | coat ratio is less than 0.8.

  According to the present embodiment, since the first film ratio in the electrode body 2 is 0.8 or more and 1.2 or less, the upper plate 32 is installed so as to be above the bottom plate 33 in the vertical direction during use. Even so, the uniformity of the coating distribution within the electrode body 2 is maintained. Therefore, since local deterioration in the electrode body 2 is suppressed, it is possible to suppress variations in durability.

[8. Method for manufacturing power storage element]
Next, the manufacturing method of the electrical storage element 1 of this invention is demonstrated.

  FIG. 4 is a process diagram illustrating the method for manufacturing the energy storage device according to Embodiment 1 of the present invention. The process diagram shown in the figure explains from the step of injecting the electrolytic solution 6 to the step of aging treatment in the manufacturing process of the electric storage element 1. In the following, the steps before the step of injecting the electrolytic solution 6 and the steps after the aging step are not particularly different from the steps that have been used in the past and are the same as the steps that are usually used. Omitted.

  First, an electrolytic solution 6 containing a film forming agent as an additive is injected into the container 3 from an electrolytic solution injection port (a liquid injection process). In the liquid injection process, the electric storage element is arranged so that the upper plate 32 is below the bottom plate 33 in the direction of gravity.

  Next, in order to infiltrate the electrolyte 6 into the electrode body 2 after the pouring step, the power storage device 1 is left for a predetermined period (leaving step: not shown). During this time, the injected electrolyte 6 gradually infiltrates between the positive electrode plate and the separator and between the negative electrode plate and the separator of the electrode body 2 by capillary action. As the electrolyte 6 enters the electrode body 2, the conductivity between the positive electrode plate and the negative electrode plate increases and the battery resistance value decreases.

  Next, the storage element 1 is precharged and the electrolyte injection port is sealed (preliminary charge + sealing step). By this preliminary charging, a film is formed on the electrode by the additive contained in the electrolytic solution 6 that has already penetrated into the electrode body 2.

  In the preliminary charging + sealing step, preliminary charging may be performed after the sealing process. However, during the precharge period, it is assumed that gas is generated due to the decomposition reaction of the additive. From the viewpoint of preventing the battery from being swollen by the generated gas, it is preferable to release the generated gas to the outside of the container 3 in advance. Therefore, it is preferable to perform the sealing process after the preliminary charging is performed.

  Moreover, the said precharge process may be abbreviate | omitted from the relationship with the aging process mentioned later.

  Next, the electrode assembly 2 is impregnated with the free electrolyte solution 60 containing a film forming agent as an additive to form a film on the surfaces of the positive electrode and the negative electrode (aging process). In this aging process, the electricity storage device 1 is installed such that the upper plate 32 is disposed below the bottom plate 33 in the vertical direction. In other words, the storage element 1 is installed so that the positive electrode terminal 4 and the negative electrode terminal 5 are arranged on the lower side in the vertical direction, and aging is executed. In addition, as conditions of an aging process, it is left to stand in a 45 degreeC thermostat for 15 hours, for example in the state which set SOC (State Of Charge) to 80%.

  The power storage device 1 manufactured through the above steps is scheduled to be used with the upper plate 32 disposed above the bottom plate 33 in the vertical direction during actual use after the manufacturing is completed. In other words, the electricity storage device 1 is planned to be installed and used such that the second end, which is the region A, is located above the first end, which is the region B, in the vertical direction.

  When the upper plate 32 is provided with an electrolyte inlet and the upper plate 32 is poured upward, the free electrolyte 60 is present inside the bottom plate 33 after the injection. When the aging process is performed in this installation state, the amount of film formation is larger in the region B on the bottom plate 33 side than in the region A on the upper plate 32 side, and the film distribution becomes uneven.

  On the other hand, according to the manufacturing method of power storage device 1 according to the above-described embodiment, the aging process is performed in a state where positive electrode terminal 4 and negative electrode terminal 5 are arranged at positions other than the upper side in the vertical direction. That is, in the aging process, the storage element 1 is installed so that the vertical direction of the power storage element 1 is reversed with respect to the use state, so that the free electrolyte 60 is not unevenly distributed inside the bottom plate 33 during the aging process. Thereby, even if it is a case where the electrical storage element 1 is used by installing the upper plate 32 or the side wall on the upper side in the vertical direction, the uniformity of the film distribution in the electrode body 2 is maintained. Therefore, since local deterioration in the electrode body 2 is suppressed, it is possible to suppress variations in durability.

(Embodiment 2)
In the first embodiment, the upper plate 32 side with respect to the power storage element used in the state where the upper plate 32 side (region A) of the container 3 is arranged on the upper side in the vertical direction than the bottom plate 33 side (region B). The power storage element that performs aging treatment in a state where the power storage element is arranged so that (Area A) is below the bottom plate 33 side (Area B) in the vertical direction, and a method for manufacturing the same have been described. On the other hand, in the present embodiment, for the storage element used in a state where the positive side wall 34 side (region C) or the negative side wall 35 side (region D) is arranged on the upper side in the vertical direction, A power storage element that performs an aging process in a state where the power storage element is arranged so that the positive side wall 34 side (region C) is below the negative side wall 35 side (region D) in the vertical direction will be described. In addition, the electricity storage element 10 according to the present embodiment has a container 3, a positive electrode terminal 4, a negative electrode terminal 5, an electrolytic solution 6, a positive electrode current collector 7, and a negative electrode as compared with the electricity storage element 1 according to the first embodiment. The configuration of the current collector 8 is the same, and the distribution of the film formation amount in the electrode body 2 and the arrangement state during aging are different as the configuration. Hereinafter, description of the same points as the power storage element 1 and the manufacturing method thereof according to Embodiment 1 will be omitted, and only different points will be described.

[1. Electrode body film formation]
5A is a cross-sectional view of the electricity storage device according to Embodiment 2 of the present invention during a first use, and FIG. 5B is a cross-section of the electricity storage device according to Embodiment 2 of the present invention during a second use. FIG.

  As shown in FIG. 5A, during the first use, the power storage device 10 is installed and used such that the positive electrode side wall 34 is disposed above the negative electrode side wall 35 in the gravitational direction. In this state, the electrode body 2 is impregnated with the electrolytic solution 6 between the positive electrode and the negative electrode. Further, the free electrolytic solution 60 not impregnated in the electrode body 2 remains inside the negative electrode side wall 35.

  As shown in FIG. 5B, during the second use, the storage element 10 is installed and used such that the negative electrode side wall 35 is disposed above the positive electrode side wall 34 in the gravitational direction. In this state, the electrode body 2 is impregnated with the electrolytic solution 6 between the positive electrode and the negative electrode. In addition, the free electrolyte 60 that is not impregnated inside the electrode body 2 remains inside the positive electrode side wall 34.

  Here, the case of the conventional electrical storage element is demonstrated. When the power storage element is used in the state shown in FIG. 5A, the additive undergoes reductive decomposition on the negative electrode current collector 8 that connects the negative electrode and the negative electrode terminal 5. Therefore, even when the free electrolyte 60 is sucked up in the direction of the positive electrode side wall 34 (vertically upward) through the separator, the concentration gradient of the additive becomes remarkable between the upper side and the lower side in the vertical direction. Distribution is non-uniform.

  On the other hand, the electrical storage element 10 according to the present embodiment is subjected to an aging process in which the positive side wall 34 is disposed below the negative side wall 35 in the gravity direction at the time of manufacture.

  FIG. 6 is a cross-sectional view of the energy storage device according to Embodiment 2 of the present invention during aging. As shown in the figure, in the energy storage device 10 according to the present embodiment, the positive side wall 34 is disposed below the negative side wall 35 in the gravity direction in the aging process at the time of manufacture. Thereby, in the period of the aging process, the free electrolyte 60 remains in the vicinity of the inside of the positive electrode side wall 34. Therefore, even when the additive concentration on the negative electrode side has a higher concentration gradient than the additive concentration on the positive electrode side due to reductive decomposition of the additive on the negative electrode current collector 8 at the time of manufacture, after the aging step, It is possible to alleviate the concentration gradient in film formation.

  After this aging process, the second is the ratio of the film formation amount per unit volume in the region C on the positive electrode terminal 4 side to the film formation amount per unit volume in the region D on the negative electrode terminal 5 side in the electrode body 2. The film ratio is 0.8 or more and 1.2 or less. Here, the region D is a first end portion that is one of the end portions of the electrode body 2, and the region C is a first end portion of the end portions of the electrode body 2. It is the 2nd edge part located in the other side.

  When the aging process according to the present embodiment is not executed, the second film ratio is less than 0.8.

  FIG. 7 is a configuration diagram of the power storage device according to the second embodiment of the present invention during the third use. Specifically, FIG. 2 shows a configuration when the battery module 100 including a plurality of power storage elements is used. In the battery module 100, the storage element 1 </ b> A arranged such that the positive electrode side wall 34 is above the negative electrode side wall 35 in the gravitational direction, and the negative electrode side wall 35 is above the positive electrode side wall 34 in the gravitational direction. The power storage elements 1 </ b> B arranged in the are alternately arranged. Thereby, the negative electrode terminal 5 of the electrical storage element 1A and the positive electrode terminal 4 of the electrical storage element 1B are connected in proximity, and the positive terminal 4 of the electrical storage element 1A and the negative electrode terminal 5 of the electrical storage element 1B are connected in proximity. The In the battery module 100 configured as described above, the additive is easily reduced and decomposed on the negative electrode current collector 8 particularly in the power storage element 1A in which the negative electrode side wall 35 is disposed below. Furthermore, the separator generally has a slower suction speed of the electrolytic solution 6 in the width direction (TD direction) than in the winding direction. For this reason, in the battery module 100, in particular, for the electricity storage device 1A, the positive electrode side wall 34 is disposed below the negative electrode side wall 35 in the gravitational direction in the aging process at the time of manufacture. Can be relaxed and the concentration distribution can be made uniform.

  According to the present embodiment, since the second film ratio in the electrode body 2 is 0.8 or more and 1.2 or less, the region C on the positive electrode side wall 34 side is the region D on the negative electrode side wall 35 side during use. Even if it is installed on the upper side in the vertical direction, the uniformity of the coating distribution in the electrode body 2 is maintained. Therefore, since local deterioration in the electrode body 2 is suppressed, it is possible to suppress variations in durability.

[2. Method for manufacturing power storage element]
Next, the manufacturing method of the electrical storage element 10 of this invention is demonstrated.

  FIG. 8 is a process diagram for explaining the method for manufacturing the energy storage device according to Embodiment 2 of the present invention. The process diagram shown in the figure explains from the step of injecting the electrolytic solution 6 to the step of aging treatment in the manufacturing process of the electricity storage device 10. In the following, the steps before the step of injecting the electrolytic solution 6 and the steps after the aging step are not particularly different from the steps that have been used in the past and are the same as the steps that are usually used. Omitted. Moreover, below, description is abbreviate | omitted about the same point as the manufacturing method of the electrical storage element 1 which concerns on Embodiment 1, and it demonstrates focusing on a different point.

  The liquid injection process, the leaving process, and the preliminary charging + sealing process are the same as those described in the first embodiment.

  Through an injection step, a standing step, and a preliminary charging + sealing step, the electrode body 2 is impregnated with a free electrolyte 60 containing a film-forming agent as an additive to form a film on the surfaces of the positive electrode and the negative electrode (aging process) . In this aging process, the storage element 10 is installed such that the positive side wall 34 is disposed below the negative side wall 35 in the vertical direction. In other words, the aging is performed by installing the electricity storage element 10 so that the end portion on the positive electrode terminal 4 side is disposed on the lower side in the vertical direction. In addition, as conditions of an aging process, it is left to stand in a 45 degreeC thermostat for 15 hours, for example in the state which set SOC (State Of Charge) to 80%.

  The power storage element 10 manufactured through the above steps is scheduled to be used with the positive side wall 34 or the negative side wall 35 disposed on the upper side in the vertical direction in actual use after the manufacturing is completed. In other words, the electric storage element 1 has a second end where the second end which is the region D is higher than the first end where the region C is the vertical end, or a second end where the first end which is the region C is the region D. It is planned to be installed and used so as to be on the upper side in the vertical direction than the part.

  According to the above-described method for manufacturing power storage device 10 according to the present embodiment, the positive side wall 34 is subjected to the aging process in a state where the positive side wall 34 is disposed below the negative side wall 35 in the vertical direction. That is, in the aging process, the storage element 10 is installed and the aging is performed such that the positive electrode terminal side end is vertically lower than the negative electrode terminal side end. It is not unevenly distributed inside the negative electrode side wall 35. Thereby, in the state in which the positive electrode side wall 34 or the negative electrode side wall 35 is disposed on the upper side in the vertical direction, the film element in the electrode body 2 is kept uniform. Therefore, since local deterioration in the electrode body 2 is suppressed, it is possible to suppress variations in durability.

  According to the energy storage device and the manufacturing method thereof according to Embodiments 1 and 2, the upper plate 32 on which the positive electrode terminal 4 and the negative electrode terminal 5 are arranged is aged in a state in which the upper plate 32 is arranged on the other side than the bottom plate 33 in the vertical direction. It is processed. By the aging treatment, the film formation amount per unit volume at the end portion (regions D and B) located on the negative electrode current collector 8 side (region D) and the side opposite to the electrode terminal side (region B) of the electrode body 2 The ratio of the amount of film formation per unit volume at the ends (regions D and B) located on the positive electrode current collector 7 side (region C) and the electrode terminal side (region A) of the electrode body 2 is 0.8 or more. 1.2 or less. Thereby, even if the electrical storage element 1 according to Embodiment 1 is used with the upper plate 32 or the side wall installed on the upper side in the vertical direction, the uniformity of the film distribution in the electrode body 2 is maintained. Further, even when the power storage device 10 according to the second embodiment is used with the positive electrode side wall 34 or the negative electrode side wall 35 disposed on the upper side in the vertical direction, the uniformity of the film distribution in the electrode body 2 is maintained. Is done. Therefore, since local deterioration in the electrode body 2 is suppressed, it is possible to suppress variations in durability.

[Example]
Next, it will be described in detail that power storage elements 1 and 10 having the above-described configuration can suppress variation in durability.

  First, an example of a method for manufacturing power storage elements 1 and 10 will be described. Specifically, batteries as power storage elements in Examples 1 to 7 and Comparative Examples 1 to 7 described later were produced as follows. Examples 1 to 7 all relate to power storage element 1 or 10 according to the above-described embodiment.

(1-1) Production of Electrode Body For Examples 1 to 7 and Comparative Examples 1 to 7, an electrode body 2 was produced as follows.

LiNi _1/3 Co _1/3 Mn _1/3 O ₂ was used as the positive electrode active material, acetylene black was used as the conductive additive, and polyvinylidene fluoride (PVDF) was used as the binder. The positive electrode paste is mixed and kneaded using N-methyl-2-pyrrolidone (NMP) as a solvent so that the conductive auxiliary agent is 4.5% by weight, the binder is 4.5% by weight, and the positive electrode active material is 91% by weight. It was produced by doing. Further, the prepared positive electrode paste was applied on a 15 μm thick aluminum foil at a weight of 6.9 mg / cm ² so as to have a width of 83 mm and an unapplied portion (positive electrode active material non-formation region) width of 11 mm. Roll pressing was performed so that the active material filling density in the positive electrode mixture was 2.48 g / cc, and vacuum drying was performed to remove moisture.

As the negative electrode active material, non-graphitizable carbon having a particle size of D50 of 3.3 μm was used. PVDF was used as the binder. The negative electrode paste was prepared by mixing and kneading NMP as a solvent so that the binder was 7% by weight and the negative electrode active material was 93% by weight. The prepared negative electrode paste was applied and dried on a copper foil having a thickness of 8 μm at a weight of 3.3 mg / cm ² so that the width was 87 mm and the non-applied part (negative electrode active material non-formation region) width was 9 mm. Roll pressing was performed so that the active material filling density in the mixture was 0.98 g / cc, and vacuum drying was performed to remove moisture.

As the electrolytic solution 6 (non-aqueous electrolyte), a mixed solvent of propylene carbonate (PC): dimethyl carbonate (DMC): ethyl methyl carbonate (EMC) = 30: 30: 35 (volume ratio) and LiPF ₆ as an electrolyte salt are used. It dissolved so that it might become 1.2 mol / L after adjustment. Further, 0.5 wt% each of the compounds shown in the following (1) and (2) was added thereto as an additive.

  After laminating and winding the positive electrode, the negative electrode, and the separator, the positive electrode, the negative electrode, and the separator were inserted into the container 3 and the electrolytic solution 6 was injected. Thereafter, charging was performed for 1 hour at a current of 0.2 CA as preliminary charging, and the electrolyte injection port was sealed. In addition, 1CA is a current value when discharging a fully charged battery in one hour.

(1-2) Aging process After producing the electrode body 2 as mentioned above about Examples 1-7 and Comparative Examples 1-7, the aging process was performed as follows.

  About Comparative Examples 1-7, an electrical storage element is installed so that the upper board 32 may be arrange | positioned above the bottom board 33 in the perpendicular direction, and it is left for 15 hours in a 45 degreeC thermostat in the state which set SOC to 80%. did.

  Moreover, about Examples 1-3, an electrical storage element is installed so that the upper board 32 may be arrange | positioned below a perpendicular direction rather than the bottom board 33, and it is in a 45 degreeC thermostat in the state which set SOC to 80%. Left for 15 hours.

  In Examples 4 to 7, the storage element was installed so that the positive electrode side wall 34 was arranged below the negative electrode side wall 35 in the vertical direction, and the constant temperature was 45 ° C. with the SOC set to 80%. It was left in the tank for 15 hours.

(2-1) Installation state at the time of use About Examples 1-3 and Comparative Examples 1-3, it mentions later in the state which installed the electrical storage element so that the upper board 32 may be arrange | positioned above the bottom board 33 in the perpendicular direction. A standing test and a cycle test were conducted.

  For Examples 4 and 6, and Comparative Examples 4 and 6, with the storage element installed so that the positive side wall 34 is disposed below the negative side wall 35 in the vertical direction, A cycle test was performed.

  For Examples 5 and 7, and Comparative Examples 5 and 7, with the storage element installed so that the negative electrode side wall 35 is arranged below the positive electrode side wall 34 in the vertical direction, A cycle test was performed.

(2-2) Output Confirmation Test and Calculation of Output Retention Ratio For the battery after the aging process and before the standing test, a charging current of 5 A and a constant current and constant voltage charging of 4.2 V are performed for 3 hours in a constant temperature bath at 25 ° C. After 10 minutes of rest, the discharge capacity Q of the battery was measured by performing constant current discharge to 2.4 V at a discharge current of 5 A.

  The battery SOC (State Of Charge) is adjusted to 20% by charging 20% of the discharge capacity obtained in the capacity check test described above, and then maintained at −10 ° C. for 4 hours. The voltage discharge was performed for 1 second, and the low temperature output P0 was calculated from the current value of the first second.

  The same test was performed on the battery after the standing test, the low-temperature output P1 after the standing test was calculated, and the output retention rate was calculated by the following formula.

  Output holding ratio = P1 / P0 × 100

  The output retention after the cycle test was calculated in the same manner as described above.

(2-3) Standing test The battery was charged at a constant current of 2.5 A up to 4.03 V, and further at a constant voltage of 4.03 V for a total of 3 hours, and the SOC (State Of Charge) of the battery was set to 85%. It was stored in a thermostatic bath for 30 days (1 month). The batteries are taken out from the thermostatic chamber every 30 days and cooled to 25 ° C., and then each battery is discharged under the conditions of 5 A constant current and end voltage 2.4 V, and then the output confirmation test described in 2-2 is performed. It was. This neglect test was repeated for 6 months. Here, “SOC to 85%” represents that the amount of charged electricity is 85% with respect to the capacity of the battery.

(2-4) Charge / Discharge Cycle Test In order to determine the test conditions of the charge / discharge cycle test, the battery adjusted to 50% SOC is held at 55 ° C. for 4 hours and charged at a constant current of 40 A until the SOC reaches 80%. Thereafter, a constant current discharge of 40 A was performed from SOC 80% to SOC 20%, thereby determining a charging voltage V80 of SOC 80% and a discharging voltage V20 of SOC 20%.

  The 55 ° C. cycle test was performed at a constant current of 40 A, the cut-off voltage during charging was set to V80, the cut-off voltage during discharge was set to V20, and the test was continuously performed without setting a pause time. The cycle time is stopped every 500 hours, taken out from the thermostatic chamber, cooled to 25 ° C., and then each battery is discharged under the conditions of a 5 A constant current and a final voltage of 2.4 V. The output confirmation test was conducted. This cycle test was set to 3000 hours in total.

(2-5) Measurement of film formation amount For Examples 1 to 7 and Comparative Examples 1 to 7 after the aging step and before the standing test, a discharge current of 5 A and a constant current and constant voltage discharge of 2.0 V were obtained at 25 ° C., respectively. After 5 hours of rest, the battery was transferred into a glove box with an argon atmosphere. Then, it disassembled in the glove box and took out the positive electrode and the negative electrode from the battery container. The taken out positive and negative electrodes were washed three or more times with DMC having a purity of 99.9% or more and a water content of 20 ppm or less, and after removing the DMC by vacuum drying, the positive and negative electrodes in predetermined regions (regions A to D) were removed. The sample was cut out and transferred to an X-ray photoelectron analyzer (X-ray photoelectron analyzer AXIS-NOVA type MB5 specification manufactured by KRATOS) without touching the atmosphere, and XPS measurement was performed. Specifically, Li, C, O, P, F, S, Al, Cu, Ni, Co, and Mn were measured as measurement elements for both the positive electrode and the negative electrode, and the additive was determined from the measurement results on the outermost surface of each element. The concentration (atom%) of the sulfur (S) component contained in was calculated and defined as the film formation amount per unit volume.

  As described above, the film formation amount and the output retention rate in each region of the produced Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Table 1 below. In addition, Table 2 below shows the film formation amount and the output retention rate after being left and after being cycled in each region of Examples 4-7 and Comparative Examples 4-7.

  In Examples 1 to 3 shown in Table 1, the upper plate 32 side (region A) is set to be vertically lower than the bottom plate 33 side (region B) during aging, and the upper plate 32 is used during use. It is installed so that the side (region A) is on the upper side in the vertical direction than the bottom plate 33 side (region B). On the other hand, Comparative Examples 1 to 3 are installed such that the upper plate 32 side (region A) is on the upper side in the vertical direction than the bottom plate 33 side (region B) during both aging and use.

  In Examples 1 to 3, the value obtained by dividing the sulfur concentration (atom%) on the electrode plate upper plate side by the sulfur concentration (atom%) on the electrode plate bottom plate side (upper plate side / bottom plate side), that is, Of these, the first film ratio, which is the ratio of the film formation amount in the region A on the upper plate 32 side to the film formation amount in the region B on the bottom plate 33 side, is 0.8 to 1.2. This is used because many films can be formed in advance in areas where the additive concentration is low (film formation is small) by performing the aging process in the direction opposite to the direction of use. It is thought that the film distribution at the time was suppressed.

  On the other hand, in Comparative Examples 1 to 3, the first film ratio is less than 0.8. This is because the additive contained in the free electrolyte remaining on the bottom plate side of the container 3 is sucked in the terminal direction through the separator during use, but the additive is decomposed on the negative electrode during the operation. is there. Thereby, it is considered that a concentration gradient of the additive is generated between the bottom plate side and the top plate side of the electrode body 2 and distribution is formed in the film formation.

  In addition, due to the use in the standing test and the cycle test, in Comparative Examples 1 to 3, the output retention rate variation is ± 4%, whereas in Examples 1 to 3, the output retention rate variation is ± 2%. Has been reduced. This is considered to be because the variation in the amount of the film formed on the upper plate side and the bottom plate side of the electrode body can be reduced by applying the aging treatment according to the present invention.

  In Examples 4 to 7 shown in Table 2 above, the positive side wall 34 side (region C) is placed below the negative side wall 35 side (region D) in the vertical direction during aging. On the other hand, the comparative examples 4-7 are installed so that the upper board 32 side (area | region A) may become an upper side of the perpendicular direction rather than the baseplate 33 side (area | region B) at the time of aging.

  In Examples 4 to 7, the value obtained by dividing the sulfur concentration (atom%) on the positive electrode terminal side by the sulfur concentration (atom%) on the negative electrode terminal side (positive terminal side / negative electrode terminal side), that is, the electrode body 2, the second film ratio, which is the ratio of the film formation amount in the region C on the positive electrode terminal 4 side to the film formation amount in the region D on the negative electrode terminal 5 side, is 0.8 or more and 1.2 or less. This is considered to be because the reductive decomposition of the additive on the negative electrode current collector 8 during the treatment was prevented by arranging the positive electrode terminal 4 side downward in the vertical direction and performing the aging treatment. . Further, by setting the width direction (TD direction) of the electrode body having a slow electrolyte sucking speed to the vertical direction and performing the aging treatment with the positive electrode terminal 4 side facing downward, the positive electrode terminal side and the negative electrode in film formation It is considered that the concentration gradient between the terminal side was relaxed.

  On the other hand, in Comparative Examples 4 to 7, the second film ratio is less than 0.8. This is because the additive contained in the free electrolyte remaining on the bottom plate side of the container 3 is sucked up in the direction of the positive electrode terminal 4 or the negative electrode terminal 5 through the separator during use. It is because it is decomposed. Thereby, it is considered that a concentration gradient of the additive is generated between the negative electrode terminal side and the positive electrode terminal side of the electrode body 2 and distribution is formed in the film formation.

  Moreover, in Comparative Examples 4 to 7, the variation in the output retention rate became remarkable due to the use by the standing test and the cycle test. Specifically, there is a difference of about 10% between the output retention ratio of Comparative Examples 4 and 6 in which the positive electrode terminal is disposed in the downward direction and the output retention ratio of Comparative Examples 5 and 7 in which the negative electrode terminal is disposed in the downward direction. Was recognized. This is because, when the negative electrode terminal is arranged in the downward direction, the additive contained in the remaining free electrolyte is reduced and decomposed on the negative electrode current collector 8, so that the negative electrode terminal side of the electrode body and the positive electrode This is probably because the protective effect of the film forming agent is different between the terminal side and local deterioration occurs in the positive electrode terminal side region.

  On the other hand, in Examples 4 to 7, the variation in output retention rate was about 2%, and the durability variation could be remarkably reduced as compared with Comparative Examples 4 to 7. This is considered to be because the variation of the coating amount formed on the positive electrode terminal side and the negative electrode terminal side can be reduced by applying the aging treatment according to the present invention.

  As mentioned above, although Embodiment 1, 2 of this invention and the electrical storage element which concerns on those Examples, and its manufacturing method were demonstrated, this invention is not limited to the said embodiment and Example.

  That is, the embodiments and examples disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  In the first and second embodiments and the examples thereof, for example, the state in which the upper plate 32 side (region A) is arranged in the vertical direction above the bottom plate 33 side (region B), etc. Is the upper side (or the lower side) in the vertical direction from B. This expression not only means that A is arranged directly above (directly below) B in the vertical direction, but the distance between the plane normal to the vertical direction and A is This includes the case where the distance is larger (smaller) than the distance.

  The present invention can be applied to non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries that require durability.

DESCRIPTION OF SYMBOLS 1, 1A, 1B, 10 Electric storage element 2 Electrode body 3 Container 4 Positive electrode terminal 5 Negative electrode terminal 6 Electrolyte 7 Positive electrode collector 8 Negative electrode collector 31 Injection stopper 32 Top plate 33 Bottom plate 34 Positive electrode side wall 35 Negative electrode side wall 60 Free electrolyte 100 Battery module

Claims (2)

An electrode body having a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, a container for housing the electrode body, and a positive electrode terminal and a negative electrode terminal disposed on the same surface of the container. A method of manufacturing a storage element,
An injection step of injecting an electrolytic solution containing a film forming agent containing sulfur as an additive into the container from an electrolytic solution injection port provided on the same surface;
After the injection step, a sealing step of sealing the electrolyte solution inlet,
An aging step of impregnating the electrode body with the electrolytic solution and performing aging for forming a film on the surfaces of the positive electrode and the negative electrode,
In the aging step, the positive electrode terminal and the negative electrode terminal are arranged on the lower side in the vertical direction with respect to the storage element that is to be used with the positive electrode terminal and the negative electrode terminal arranged on the upper side in the vertical direction. A method of manufacturing a power storage element, wherein the power storage element is installed and the aging is performed. An electrode body having a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, a container for housing the electrode body, and a positive electrode terminal and a negative electrode terminal disposed on the same surface of the container. A method of manufacturing a storage element,
An injection step of injecting an electrolytic solution containing a film forming agent containing sulfur as an additive into the container from an electrolytic solution injection port provided on the same surface;
After the injection step, a sealing step of sealing the electrolyte solution inlet,
An aging step of impregnating the electrode body with the electrolytic solution and performing aging for forming a film on the surfaces of the positive electrode and the negative electrode,
In the aging step, the positive electrode terminal side end portion of the electrode body is to be used with the positive electrode terminal side end portion or negative electrode terminal side end portion arranged on the upper side in the vertical direction. A method for manufacturing a storage element, wherein the aging is performed by installing the storage element so as to be lower than a terminal side end in a vertical direction.

Images