JP5857839B2 - Electric storage element, method for manufacturing electric storage element, and non-aqueous electrolyte - Google Patents

Description

  The present invention relates to a storage element having a positive electrode and a negative electrode that occlude and release lithium ions and a non-aqueous electrolyte, a method for manufacturing the storage element, and a non-aqueous electrolyte.

  The shift from gasoline cars to electric cars has become important as a global environmental problem. For this reason, use of electrical storage elements such as nonaqueous electrolyte secondary batteries as a power source for electric vehicles has been studied. Here, in order to use the power storage element efficiently, it is important to improve battery performance such as high-temperature storage characteristics.

  For this reason, the electrical storage element which uses the nonaqueous electrolyte solution which added the ionic metal complex conventionally is proposed (for example, refer patent document 1). In this electricity storage device, battery performance such as high-temperature storage characteristics can be improved by using a non-aqueous electrolyte prepared by adding an ionic metal complex represented by the general formula disclosed in Patent Document 1. .

JP 2005-285491 A

  Here, when a negative electrode active material having a small particle diameter is used for the negative electrode, the output of the power storage device can be increased. However, when a negative electrode active material having a small particle size is used, the contact area between the negative electrode active material and the non-aqueous electrolyte is increased, so that the negative electrode active material is reduced by side reactions such as reductive decomposition of the non-aqueous electrolyte. to degrade. For this reason, in the negative electrode active material having a small particle diameter, the deterioration of the active material itself and the deterioration due to the side reaction proceed simultaneously. And if degradation of the said negative electrode active material advances, battery performance will be reduced.

  For this reason, it is conceivable to improve battery performance by using a non-aqueous electrolyte solution to which an ionic metal complex in the above-described conventional power storage element is added. However, the ionic metal complex generally includes many types of compounds. The general formula is shown. For this reason, in the conventional power storage element, it is not clear which compound represented by the general formula can effectively improve battery performance, and the amount of the compound used is not clear. Also, the type and particle size of the negative electrode active material effective for improving the battery performance are not clear.

  As described above, when a negative electrode active material having a small particle diameter is used, the output of the power storage device can be increased. However, the battery performance is deteriorated due to the deterioration of the negative electrode active material due to the side reaction of the nonaqueous electrolytic solution. And in the conventional electrical storage element, in this case, the type and amount of the compound used for improving the battery performance and the type and particle size of the negative electrode active material effective for improving the battery performance are not clear. For this reason, in the electrical storage element which uses the conventional nonaqueous electrolyte, while aiming at high output, there exists a problem that performance, such as a high temperature storage characteristic, cannot be improved effectively.

  The present invention has been made in order to solve the above-described problem, and can achieve high output and can effectively improve performance such as high-temperature storage characteristics, a method for manufacturing the power storage element, and non-water An object is to provide an electrolytic solution.

  In order to achieve the above object, a power storage device according to one embodiment of the present invention is a power storage device including a positive electrode and a negative electrode including a substance that absorbs and releases lithium ions, and a nonaqueous electrolytic solution, The electrolyte includes lithium difluorobisoxalate phosphate, which is a first additive represented by the following chemical formula (1), and lithium tetrafluorooxalate, which is a second additive represented by the following chemical formula (2). And the amount of the first additive added is 0.3% by weight or more and 1.0% by weight or less of the total weight of the non-aqueous electrolyte, and the second additive The addition amount is 0.05 to 0.3 times the addition amount of the first additive, and the negative electrode comprises non-graphitizable carbon having an average particle diameter D50 of 6 μm or less as a negative electrode active material. Including.

  According to this, the non-aqueous electrolyte of the electricity storage device includes the first additive represented by the chemical formula (1) and the second additive represented by the chemical formula (2), and the first addition The addition amount of the additive is 0.3% by weight or more and 1.0% by weight or less of the total weight of the non-aqueous electrolyte, and the addition amount of the second additive is the addition amount of the first additive. It is 0.05 times or more and 0.3 times or less. Moreover, the negative electrode of the said electrical storage element contains the non-graphitizable carbon whose average particle diameter D50 is 6 micrometers or less as a negative electrode active material.

  Here, when a negative electrode active material having a small particle size is used for increasing the output of the electricity storage device, the contact area between the negative electrode active material and the non-aqueous electrolyte increases, so the reductive decomposition of the non-aqueous electrolyte The negative electrode active material deteriorates due to side reactions such as these. That is, in the negative electrode active material having a small particle size, the deterioration of the active material itself and the deterioration due to the side reaction proceed simultaneously.

  Therefore, as a result of intensive studies and examinations, the inventors of the present application, in a negative electrode active material containing non-graphitizable carbon having an average particle diameter D50 of 6 μm or less, include the first additive and the second additive. It was found that the side reaction of the non-aqueous electrolyte can be remarkably suppressed by adding the above-mentioned predetermined amount to the non-aqueous electrolyte. Thus, the inventors of the present application have found that, in the power storage element, performance such as high-temperature storage characteristics can be effectively improved by largely suppressing deterioration due to the side reaction of the negative electrode active material. For this reason, the electric storage element has a negative electrode active material containing non-graphitizable carbon having an average particle diameter D50 of 6 μm or less in the negative electrode, and the first additive and the second additive described above, By adding the predetermined amount to the non-aqueous electrolyte, it is possible to achieve high output and to effectively improve performance such as high-temperature storage characteristics.

  Preferably, the non-graphitizable carbon has an average particle diameter D50 of 2 μm or more.

  According to this, non-graphitizable carbon having an average particle diameter D50 of 2 μm or more is used. That is, non-graphitizable carbon having an average particle diameter D50 smaller than 2 μm is difficult to handle because the particle diameter is too small, and the production cost is increased. In addition, when the non-graphitizable carbon is applied to the negative electrode, productivity problems such as inability to apply stably occur. For this reason, productivity improvement and cost reduction can be aimed at by using the non-graphitizable carbon whose average particle diameter D50 is 2 micrometers or more.

  In order to achieve the above object, a method for manufacturing a power storage device according to one embodiment of the present invention is a method for manufacturing a power storage device including a positive electrode and a negative electrode containing a substance that absorbs and releases lithium ions, and a nonaqueous electrolytic solution. A lithium difluorobisoxalate phosphate as a first additive represented by the following chemical formula (3) and a lithium tetrafluorooxa compound as a second additive represented by the following chemical formula (4) An electrolyte solution injection step of injecting a non-aqueous electrolyte to which the rate phosphate is added into the electricity storage device, and the electricity storage device into which the non-aqueous electrolyte solution is injected in the electrolyte solution injection step are A precharging step of performing precharging more than once, and in the electrolyte injection step, the negative electrode containing the non-graphitizable carbon having an average particle diameter D50 of 6 μm or less as a negative electrode active material In the electric element, the amount of the first additive that is 0.3% by weight or more and 1.0% by weight or less of the total weight of the non-aqueous electrolyte and the amount of the first additive added is 0.05 times or more and 0. Inject a non-aqueous electrolyte solution to which the second additive of 3 times or less is added.

  According to this, in the method for manufacturing a power storage device, a predetermined amount of the first additive and the second additive are added to the power storage device including non-graphitizable carbon having an average particle diameter D50 of 6 μm or less. Inject a water electrolyte and perform one or more pre-charges before sealing. Here, the inventors of the present invention perform high-temperature storage by performing one or more pre-charges before sealing the non-aqueous electrolyte injection hole in a state where the non-aqueous electrolyte is injected into the electric storage element. It has been found that performance such as characteristics can be effectively improved. For this reason, according to the manufacturing method of the said electrical storage element, it can manufacture the electrical storage element which can improve performances, such as a high-temperature storage characteristic, effectively by performing one or more preliminary charges before sealing. it can.

  In addition, the present invention can be realized not only as such a power storage element or a method for manufacturing the power storage element, but also by adding the first additive and the second additive and having an average particle diameter D50 of 6 μm or less. It can also be realized as a non-aqueous electrolyte used in a power storage element having a negative electrode containing non-graphitizable carbon as a negative electrode active material.

  According to the electricity storage device of the present invention, it is possible to achieve high output and to effectively improve performance such as high-temperature storage characteristics.

It is an external appearance perspective view of the electrical storage element which concerns on embodiment of this invention. It is a flowchart which shows an example of the manufacturing method of the electrical storage element which concerns on embodiment of this invention. The figure which shows the capacity | capacitance retention of an electrical storage element when the addition amount of a 2nd additive, the kind of negative electrode active material, and a particle diameter are changed when 0.2 weight% of 1st additives are added. is there. The figure which shows the capacity | capacitance retention of an electrical storage element when the addition amount of a 2nd additive, the kind of negative electrode active material, and a particle diameter are changed when 0.3 weight% of 1st additives are added. is there. The figure which shows the capacity | capacitance retention of an electrical storage element when the addition amount of a 2nd additive, the kind of negative electrode active material, and a particle diameter are changed when 0.5 weight% of 1st additives are added. is there. The figure which shows the capacity | capacitance retention of an electrical storage element when the addition amount of a 2nd additive, the kind of negative electrode active material, and a particle diameter are changed when 1.0 weight% of a 1st additive is added. is there. The figure which shows the capacity | capacitance retention of an electrical storage element when the addition amount of a 2nd additive, the kind of negative electrode active material, and a particle diameter are changed when 1.2 weight% of 1st additives are added. is there. The figure which shows the direct current | flow resistance increase rate of an electrical storage element when the addition amount of a 2nd additive, the kind of negative electrode active material, and a particle diameter are changed when 0.2 weight% of 1st additives are added. It is. The figure which shows the direct current | flow resistance increase rate of an electrical storage element when the addition amount of a 2nd additive, the kind of negative electrode active material, and a particle diameter are changed when 0.3 weight% of 1st additives are added. It is. The figure which shows the direct current | flow resistance increase rate of an electrical storage element when the addition amount of a 2nd additive, the kind of negative electrode active material, and a particle diameter are changed when 0.5 weight% of 1st additives are added. It is. The figure which shows the direct current | flow resistance increase rate of an electrical storage element when the addition amount of a 2nd additive, the kind of negative electrode active material, and a particle diameter are changed when 1.0 weight% of 1st additive is added. It is. The figure which shows the direct current | flow resistance increase rate of an electrical storage element when the addition amount of a 2nd additive, the kind of negative electrode active material, and a particle diameter are changed when 1.2 weight% of 1st additives are added. It is.

  Hereinafter, a power storage device and a method for manufacturing the same 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. The numerical values, shapes, materials, constituent elements, arrangement positions and connecting forms of the constituent elements, steps, order of steps, 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.

  First, the structure of the electrical storage element which concerns on embodiment of this invention is demonstrated.

  FIG. 1 is an external perspective view of a power storage device 1 according to an embodiment 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. Note that the power storage element 1 may be a capacitor. 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, and a nonaqueous electrolytic solution 6.

  Although detailed illustration is omitted, the electrode body 2 includes a positive electrode, a negative electrode, and a separator, and is a member that can store electricity. That is, the electrode body 2 is an electrode group in which a positive electrode plate and a negative electrode plate containing a substance that occludes and releases lithium ions are wound in a spiral shape via a separator, and is housed in the container 3.

  The separator is a microporous sheet made of a resin, and the separator is impregnated with a nonaqueous electrolytic solution 6 containing an organic solvent and an electrolyte salt. For example, the positive electrode plate and the negative electrode plate are coated on a surface of a metal current collector with a mixture paste in which an active material, a binder, a conductive additive or the like and an organic solvent are mixed, dried, and rolled. It is formed by adjusting the thickness of the mixture layer by pressing with a press or the like.

  In FIG. 1, an ellipse is shown as the shape of the electrode group, but it may be a circle. The shape of the electrode group is not limited to a wound type, and may be a shape in which flat plate plates are laminated.

  Here, the positive electrode plate, the negative electrode plate, the separator and the like used in the electricity storage device 1 according to the present invention are not particularly different from those conventionally used, and those normally used can be used.

As a positive electrode active material used for the electrical storage element 1, a known material can be appropriately used as long as it is a positive electrode active material capable of occluding and releasing lithium ions. For example, a composite oxide represented by Li _x MO _y (M represents at least one transition metal) (Li _x CoO ₂ , Li _x NiO ₂ , Li _x Mn ₂ O ₄ , Li _x MnO ₃ , Li _x Ni _{y Co (1-y) O} 2, Li x Ni y Mn z Co , etc. _{(1-y-z) O} 2, Li x Ni y Mn (2-y) O 4), _or, Li _w Me x (XO _y ) _z (Me represents at least one kind of transition metal, and X represents, for example, P, Si, B, V) polyanion compounds (LiFePO ₄ , LiMnPO ₄ , LiNiPO ₄ , LiCoPO ₄ , Li ₃ V ₂ (PO) ₄ ) ₃ , Li ₂ MnSiO ₄ , Li ₂ CoPO ₄ F, etc.). The elements or polyanions in these compounds may be partially substituted with other elements or anion species, and the surface is coated with a metal oxide such as ZrO ₂ , WO ₂ , MgO, Al ₂ O ₃ or carbon. May be. Furthermore, conductive polymer compounds such as disulfide, polypyrrole, polyaniline, polyparastyrene, polyacetylene, and polyacene materials, pseudographite-structured carbonaceous materials, and the like are included, but the invention is not limited thereto. Moreover, these compounds may be used independently and may mix and use 2 or more types.

  Further, as the negative electrode active material used for the electricity storage device 1, non-graphitizable carbon (hard carbon) having an average particle diameter D50 of 6 μm or less is used. Here, the average particle diameter D50 (also referred to as 50% particle diameter or median diameter) is the particle diameter when the cumulative value is 50% in the particle diameter distribution, and more specifically, there is powder. When the particle size is divided into two, it is the diameter when the large side and the small side are equivalent.

  In addition, non-graphitizable carbon having an average particle diameter D50 smaller than 2 μm is difficult to handle because the particle diameter is too small, and the production cost increases. In addition, when the non-graphitizable carbon is applied to the negative electrode, productivity problems such as inability to apply stably occur. For this reason, the average particle diameter D50 of the non-graphitizable carbon is preferably 2 μm or more.

  The positive electrode active material and the negative electrode active material are mixed with a binder, a conductive auxiliary agent, and the like, respectively, applied to the surface of the current collector, pressed and dried, thereby forming a positive electrode and a negative electrode.

  As the current collector, copper, nickel, iron, stainless steel, titanium, aluminum, calcined carbon, conductive polymer, conductive glass, Al—Cd alloy, or the like can be used. Furthermore, the surface of the current collector made of these materials is obtained by crosslinking polysaccharide polymer polymers such as chitosan and chitin with a crosslinking agent for the purpose of adhesion, conductivity and reduction resistance, carbon, nickel, titanium It may be treated with silver or silver.

  As the conductive material mixed with the positive electrode active material and the negative electrode active material, conductive powder materials such as carbon powder and carbon fiber are preferably used. As the carbon powder, various carbon blacks such as acetylene black, furnace black, ketjen black, and graphite powder are preferable. A conductive material can be used alone or in combination of two or more. What is necessary is just to select suitably the quantity of the electrically conductive material contained in a positive electrode compound material and a negative electrode compound material according to the kind and quantity of a positive electrode active material and a negative electrode active material.

  Moreover, you may use what performed the process which raises the electroconductivity to the particle | grain surface of the said positive electrode active material instead of using a electrically conductive material or together with the use of a electrically conductive material.

  The binder is not particularly limited, and examples thereof include polyvinylidene fluoride (PVDF), polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylonitrile, polyacrylic acid, and polyacrylic. Acid methyl ester, polyacrylic acid ethyl ester, polyacrylic acid hexyl ester, polymethacrylic acid, polymethacrylic acid methyl ester, polymethacrylic acid ethyl ester, polymethacrylic acid hexyl ester, polyvinylpyrrolidone, hexafluoropolypropylene, styrene butadiene rubber, carboxy Examples include methyl cellulose. These may be used alone or in combination of two or more.

  Moreover, as the separator used for the electricity storage element 1, a synthetic resin microporous film made of a polyolefin resin such as a woven fabric, a nonwoven fabric, or polyethylene that is insoluble in an organic solvent is used, and a plurality of materials, weight average molecular weights and porosity are different. Those obtained by laminating microporous membranes, those containing appropriate amounts of various plasticizers, antioxidants, flame retardants, etc. in these microporous membranes, and inorganic oxides such as silica on one and both sides May be applied. In particular, a synthetic resin microporous film can be suitably used. Among them, polyolefin-based microporous membranes such as polyethylene and polypropylene microporous membranes, polyethylene and polypropylene microporous membranes combined with aramid and polyimide, or microporous membranes that combine these, have thickness, membrane strength, membrane It is preferably used in terms of resistance.

  Furthermore, a separator can also be used by using a solid electrolyte such as a polymer solid electrolyte. Further, a synthetic resin microporous membrane and a polymer solid electrolyte may be used in combination. In this case, a porous polymer solid electrolyte membrane may be used as the polymer solid electrolyte, and the polymer solid electrolyte may further contain an electrolytic solution. However, in this case, since the battery output is reduced, it is preferable to keep the polymer solid electrolyte in a minimum amount.

  The positive electrode terminal 4 is disposed on the upper portion of the container 3 and is connected to the positive electrode plate via a positive electrode lead.

  The negative electrode terminal 5 is disposed on the upper portion of the container 3 and is connected to the negative electrode plate via a negative electrode lead.

  In addition, an electrolyte injection hole 31 is disposed in the upper part of the container 3.

  For the positive electrode terminal 4, the negative electrode terminal 5, the container 3, and the current collector that connects the positive electrode terminal 4 and the negative electrode terminal 5 and the electrode body 2, those conventionally used can be used as they are.

  As the non-aqueous electrolyte solution 6, there is no particular limitation on the type thereof as long as it does not impair the performance as the electrolyte secondary battery, and various types can be selected. There is no restriction | limiting in particular in the organic solvent of the non-aqueous electrolyte 6, For example, ethylene carbonate, propylene carbonate, butylene carbonate, trifluoropropylene carbonate, (gamma) -butyrolactone, (gamma) -valerolactone, a sulfolane, 1, 2- dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, 2-methyl-1,3-dioxolane, dioxolane, fluoroethyl methyl ether, ethylene glycol diacetate, propylene glycol diacetate, ethylene glycol dipropionate, propylene glycol Dipropionate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, dimethyl carbonate, diethyl Carbonate, ethyl methyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, dipropyl carbonate, methyl isopropyl carbonate, ethyl isopropyl carbonate, diisopropyl carbonate, dibutyl carbonate, acetonitrile, fluoroacetonitrile, ethoxypentafluorocyclotriphosphazene, diethoxytetrafluorocyclo Alkoxy and halogen-substituted cyclic phosphazenes such as triphosphazene and phenoxypentafluorocyclotriphosphazene or chain phosphazenes, phosphate esters such as triethyl phosphate, trimethyl phosphate and trioctyl phosphate, triethyl borate, tributyl borate, etc. Borate esters, N-methyloxazolidinone, N-ethyl Nonaqueous solvents such as Kisazorijinon the like. When a solid electrolyte is used, a porous polymer solid electrolyte membrane may be used as the polymer solid electrolyte, and an electrolyte solution may be further contained in the polymer solid electrolyte. Moreover, when using a gel-like polymer solid electrolyte, the electrolyte solution which comprises gel and the electrolyte solution contained in the pore etc. may differ. However, when high output is required as in HEV applications, it is more preferable to use a non-aqueous electrolyte alone as the electrolyte than to use a solid electrolyte or a polymer solid electrolyte.

As the electrolyte salt in the nonaqueous electrolytic solution 6 is not particularly _{limited, LiClO 4, LiBF 4, LiAsF} 6, LiPF 6, LiCF 3 SO 3, LiN (SO 2 CF 3) 2, LiN (SO 2 C 2 _{F 5) 2, LiN (SO} 2 CF 3) (SO 2 C 4 F 9), LiSCN, LiBr, LiI, Li 2 SO 4, Li 2 B 10 Cl 10, NaClO 4, NaI, NaSCN, NaBr, KClO 4 , Ionic compounds such as KSCN, and mixtures of two or more thereof.

  In the electrical storage element 1, these organic solvents and electrolyte salt are combined and used as an electrolytic solution. In these electrolytic solutions, it is preferable to use a mixture of ethylene carbonate, dimethyl carbonate, and methyl ethyl carbonate because the lithium ion conductivity is maximized.

  Here, the non-aqueous electrolyte 6 contains a first additive and a second additive for the purpose of promoting the permeation of lithium ions by forming a film on the electrode.

The first additive is lithium difluorobisoxalate phosphate (LiPF ₂ (Ox) ₂ ) represented by the following chemical formula (5).

The second additive is lithium tetrafluorooxalate phosphate (LiPF ₄ (Ox)) represented by the following chemical formula (6).

  Here, the addition amount of the first additive is not less than 0.3% by weight and not more than 1.0% by weight of the total weight of the non-aqueous electrolyte 6, and the addition amount of the second additive is It is 0.05 times or more and 0.3 times or less of the addition amount of 1 additive.

Further, the third additive may be added to the nonaqueous electrolytic solution 6 as long as the addition amounts of the first additive and the second additive satisfy the above-described relationship. Examples of the third 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-propa Cyclic sulfonic acid esters such as sultone, 1,4-butane sultone, 1,3-propene sultone, 1,4-butene sultone, methyl methyl disulfonate, ethyl methyl disulfonate, propyl methyl disulfonate, ethyl ethyl disulfonate, ethyl disulfone Cyclic disulfonic acid esters such as propyl acid, bis (vinylsulfonyl) methane, methyl methanesulfonate, ethyl methanesulfonate, propyl methanesulfonate, methyl ethanesulfonate, ethyl ethanesulfonate, propyl ethanesulfonate, benzenesulfonic acid Methyl, ethyl benzenesulfonate. Propyl benzene sulfonate, phenyl methane sulfonate, phenyl ethane sulfonate, phenyl propane sulfonate, methyl benzyl sulfonate, ethyl benzyl sulfonate, benzyl sulfonate, benzyl methane sulfonate, benzyl ethane sulfonate, benzyl propane sulfonate, etc. Chain sulfonic acid esters, 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, phenylethylenesulfite, dimethyl sulfate, diethyl sulfate, diisopropyl sulfate, dibutyl sulfate, ethylene glycol sulfate, propylene glycol sulfate, butylene glycol sulfate, sulfate esters such as pentene glycol sulfate, Benzene, toluene, xylene, fluorobenzene, biphenyl, cyclohexylbenzene, 2-fluorobiphenyl, 4-fluorobiphenyl, diphenyl ether, tert-butylbenzene, orthoterphenyl, metaterphenyl, naphthalene, fluoronaphthalene, cumene, fluorobenzene, 2 Aromatic compounds such as 1,4-difluoroanisole, halogen-substituted alkanes such as perfluorooctane, tris borate Trimethylsilyl, sulfuric bis trimethylsilyl, although silyl esters such as phosphoric acid tris trimethylsilyl and the like, but is not limited thereto. In addition, the structure and content of the additive contained in the non-aqueous electrolyte 6 can be examined by various known analysis methods. For example, GC-MS, GC-FID, ¹ H-NMR, ¹³ C-NMR, ¹⁹ F-NMR, ³¹ P-NMR and the like can be used.

  In addition, the 3rd additive may use the compound illustrated above individually or in combination of 2 or more types.

  Next, the manufacturing method of the electrical storage element 1 is demonstrated.

  FIG. 2 is a flowchart showing an example of a method for manufacturing power storage device 1 according to the embodiment of the present invention. Note that the flowchart shown in the figure explains the steps from the step of adding the additive to the step of sealing the electrolyte injection hole 31 in the manufacturing process of the electric storage element 1. In the following, the step before the step of adding the additive and the step after the step of sealing the electrolyte injection hole 31 are not particularly different from the conventionally used steps and are usually used steps. The description is omitted.

  As shown in the figure, first, as an additive addition step, the non-aqueous electrolyte 6 is mixed with lithium difluorobisoxalate phosphate as the first additive represented by the above chemical formula (5) and the above chemical formula. Lithium tetrafluorooxalate phosphate, which is the second additive represented by (6), is added (S102).

  Specifically, the first additive is 0.3% by weight or more and 1.0% by weight or less of the total weight of the nonaqueous electrolytic solution 6, and the addition amount of the first additive is 0.05 times or more and 0. Add up to 3 times the second additive. Note that the third additive may be added to the nonaqueous electrolytic solution 6.

  Then, as the electrolytic solution injection step, the nonaqueous electrolytic solution 6 in which an additive is added to the electricity storage device 1 having a negative electrode containing non-graphitizable carbon having an average particle diameter D50 of 6 μm or less as a negative electrode active material is used as an electrolytic solution. It injects from the injection hole 31 (S104). As described above, the average particle diameter D50 of the non-graphitizable carbon is preferably 2 μm or more.

  Note that the first additive and the second additive may be added to the nonaqueous electrolytic solution 6 after the nonaqueous electrolytic solution 6 is injected into the electric storage element 1. In this case, the order in which the first additive and the second additive are added is not limited, and two additives may be added simultaneously, or one of the additives may be added in order. .

  Next, as the preliminary charging step, one or more preliminary chargings are performed on the power storage element 1 having the non-aqueous electrolyte 6 to which the first additive and the second additive are added (S106).

  At this time, a film is formed on the electrode by the first additive and the second additive contained in the non-aqueous electrolyte 6 that has penetrated into the electrode body 2, and the gas generated during the film formation is still sealed. It is discharged to the outside of the battery via the electrolyte injection hole 31 that is not.

  Finally, the electrolyte injection hole 31 is sealed (S108). That is, the electrolyte solution injection hole 31 is closed and the container 3 is sealed.

  As described above, the first additive and the second additive are added to the nonaqueous electrolytic solution 6 of the electricity storage device 1 having non-graphitizable carbon having an average particle diameter D50 of 6 μm or less as the negative electrode active material. As a result of the preliminary charging, the function of the mixed film of the first additive and the second additive is improved, and the decrease in the capacity retention rate due to storage at high temperature is suppressed, and the direct current resistance is reduced. The increase is also suppressed.

  Hereinafter, the effect obtained by adding the first additive and the second additive to the nonaqueous electrolytic solution 6 of the electricity storage device 1 having the non-graphitizable carbon as a negative electrode active material will be described in detail. .

[Example]
The Example about the electrical storage element 1 and its manufacturing method is demonstrated. In addition, all the following Examples 1-40 are related with the electrical storage element 1 which concerns on embodiment mentioned above, and its manufacturing method. In Examples 1 to 40 and Comparative Examples 1 to 152 described below, the same conditions except for the type and amount of additive added to the non-aqueous electrolyte 6 and the type and particle size of the negative electrode active material This is what I did below.

  Specifically, the electricity storage device in Example 1 was produced as follows.

(1) Production of positive electrode plate 5% by mass of polyvinylidene fluoride as a binder, 5% by mass of acetylene black as a conductive agent, and LiNi _0.17 Co _0.66 Mn _0.17 O ₂ as a positive electrode active material. N-methyl-2-pyrrolidone was added to a mixture of 90% by mass to prepare a paste, and this was applied to both sides of a positive electrode current collector made of aluminum foil having a thickness of 20 μm and dried. Thus, a positive electrode plate was produced and a positive electrode lead was provided.

(2) Production of Negative Electrode Plate 92% by mass of non-graphitizable carbon having an average particle diameter D50 of 6 μm measured by a laser diffraction method using a laser diffraction particle size distribution analyzer SALD2200 manufactured by Shimadzu Corporation as a negative electrode active material After adding 8% by mass of a polyvinylidene fluoride as an adhesive to N-methyl-2-pyrrolidone to prepare a paste, this was applied to both sides of a negative electrode current collector made of copper foil having a thickness of 10 μm. The negative electrode plate was manufactured by drying and equipped with a negative electrode lead.

(3) Fabrication of battery A polyethylene microporous membrane was used as the separator. Moreover, as the nonaqueous electrolyte, a nonaqueous electrolyte prepared by the following method was used. That is, in a mixed solvent of ethylene carbonate (EC): dimethyl carbonate (DMC): ethyl methyl carbonate (EMC) = 3: 3: 4 (volume ratio), LiPF ₆ was dissolved to 1 mol / L after preparation, Furthermore, 0.30% by weight of the first additive represented by the chemical formula (5) and 0.02% by weight of the second additive represented by the chemical formula (6) with respect to the total mass of the nonaqueous electrolytic solution. % Was added to prepare a non-aqueous electrolyte.

  As described above, a power storage element of Example 1 having a nominal capacity of 450 mAh was manufactured using these materials in the order shown in FIG.

  Moreover, the electrical storage element in the comparative example 1 was produced as follows.

  As the negative electrode active material, graphite (graphite) having an average particle diameter D50 measured by the laser diffraction method of 6 μm was used instead of the non-graphitizable carbon in Example 1 above. Further, instead of the non-aqueous electrolyte in Example 1 described above, a non-aqueous electrolyte in which the addition amount of the first additive and the second additive was 0% by weight (not added) was used. And the electrical storage element in the comparative example 1 was produced like Example 1 except the negative electrode active material and the non-aqueous electrolyte.

  Further, as in Example 1 and Comparative Example 1, as shown in Table 1 below, power storage elements in Examples 2 to 40 and Comparative Examples 2 to 152 were manufactured. In Table 1 below, for Examples 1 to 40 and Comparative Examples 1 to 152, the type and particle size of the negative electrode active material, and the addition amounts of the first additive and the second additive added to the nonaqueous electrolyte solution It shows. That is, in Examples 2 to 40 and Comparative Examples 2 to 152, instead of the negative electrode active material and the non-aqueous electrolyte in Example 1 or Comparative Example 1, the negative electrode active materials having the types and particle sizes shown in Table 1 were used. Then, the non-aqueous electrolyte was prepared by adding the first additive and the second additive in the addition amounts shown in Table 1, and a power storage device was manufactured.

Here, “LiPF ₂ (Ox) ₂ addition amount” shown in Table 1 indicates the addition amount of the first additive added to the non-aqueous electrolyte, and “LiPF ₄ (Ox) addition amount” indicates the non-aqueous electrolyte. The addition amount of the 2nd additive added to electrolyte solution is shown. The “ratio with LiPF ₂ (Ox) ₂ ” in the “LiPF ₄ (Ox) addition amount” column is the ratio of the addition amount of the second additive to the addition amount of the first additive (LiPF ₄ ( The value of (Ox) addition amount / LiPF ₂ (Ox) ₂ addition amount) is shown.

  “Graphite_6 μm” indicates that graphite (graphite) having an average particle diameter D50 of 6 μm is used as the negative electrode active material, and “SC_6 μm” indicates graphitizable carbon having an average particle diameter D50 of 6 μm as the negative electrode active material. (Soft carbon) is used. “HC — 15 μm”, “HC — 9 μm”, “HC — 6 μm”, “HC — 5 μm”, “HC — 3 μm” and “HC — 2 μm” are negative electrode active materials having an average particle diameter D50 of 15 μm, 9 μm, 6 μm, 5 μm, 3 μm and 2 μm, respectively. It shows that non-graphitizable carbon (hard carbon) is used.

  That is, in Examples 1 to 40, the addition amount of the first additive is 0.3 wt% or more and 1.0 wt% or less of the total weight of the non-aqueous electrolyte, and the addition amount of the second additive Is not less than 0.05 times and not more than 0.3 times the addition amount of the first additive, and non-graphitizable carbon having an average particle diameter D50 of 2 μm or more and 6 μm or less is used as the negative electrode active material.

(4) Evaluation Test Next, an evaluation test (battery performance test after high-temperature storage) was performed as follows.

  Using the batteries of Examples 1 to 40 and Comparative Examples 1 to 152, an initial discharge capacity confirmation test was performed by the following method. Each battery was charged at a constant current of 450 mA up to 4.2 V at 25 ° C. and further charged at a constant voltage of 4.2 V for a total of 3 hours, and then discharged at a constant current of 450 mA at a final voltage of 2.5 V. The capacity was measured.

Next, the initial DC resistance was measured by the following method. Each battery was charged to 3.73 V at a constant current of 450 mA at 25 ° C., and further at a constant voltage of 3.73 V for a total of 3 hours, thereby setting the SOC (State Of Charge) of the battery to 50%. After each battery was held at −20 ° C. for 5 hours, the voltage (E1 ₀ ) when discharged at 90 mA (I1) for 10 seconds and the voltage (E2 ₀ ) when discharged at 225 mA (I2) for 10 seconds were measured. did. Using the above measured values, the initial DC resistance value R ₀ at −20 ° C. was calculated by R ₀ = | (E1 ₀ −E2 ₀ ) / discharge current (I1−I2) |. Here, “SOC to 50%” indicates that the amount of charged electricity is 50% with respect to the capacity of the battery.

  About each battery after initial stage discharge capacity and initial stage DC resistance measurement, the leaving test at 60 degreeC was done with the following method. The battery was charged at a constant current of 450 mA up to 4.03 V and further at a constant voltage of 4.03 V for a total of 3 hours to set the SOC of the battery to 80%, and stored in a constant temperature bath at 60 ° C. for 30 days (one month). After cooling to 25 ° C., each battery was discharged under conditions of a constant current of 450 mA and a final voltage of 2.5 V, and then charged and discharged under the same conditions as in the initial discharge capacity confirmation test. This storage test at 60 ° C. was repeated for 6 months.

  And after repeating the storage test at 60 degreeC for 6 months, the discharge capacity after a preservation | save was measured on the same conditions as the measurement of the discharge capacity implemented initially about each battery. The ratio of the discharge capacity after storage thus obtained to the initial stage was defined as the capacity retention after storage.

Next, the DC resistance value _Rx after storage was measured under the same conditions as the measurement of the DC resistance value performed initially for each battery. The increase rate (DC resistance increase rate) with respect to the initial value of the DC resistance after storage thus obtained was calculated by the following formula (R _x −R ₀ ) / R ₀ × 100.

The value of the capacity retention calculated as described above is shown in Table 2 below, and the value of the DC resistance increase rate is shown in Table 3 below. That is, in Table 2 and Table 3 below, the first additive (LiPF ₂ (Ox) ₂ ) and the second additive for Examples 1 to 40 and Comparative Examples 1 to 152 shown in Table 1 above. The amount of (LiPF ₄ (Ox)) added is compared with the capacity retention rate and DC resistance increase rate of the storage element when the type and particle size of the negative electrode active material are changed.

  3A to 3E are diagrams showing the capacity retention rate of the power storage element when the addition amount of the first additive and the second additive, the type of the negative electrode active material, and the particle diameter are changed. is there.

  Specifically, FIG. 3A shows a case where the amount of the second additive added, the type of the negative electrode active material, and the particle size are changed when 0.2 wt% of the first additive is added. It is a figure which shows the capacity | capacitance retention of an element, and the value of capacity | capacitance retention in Comparative Examples 2-4, 26-28, 50-52, 74-76, 98-100, 112-114, 126-128, 140-142 Is a graph.

Here, the horizontal axis of the graph shown in the figure shows the ratio of the added amount of the second additive (LiPF ₄ (Ox)) to the added amount of the first additive (LiPF ₂ (Ox) ₂ ). The vertical axis indicates the capacity retention rate.

  Similarly, FIG. 3B shows the electricity storage when the amount of the second additive added, the type of the negative electrode active material, and the particle diameter are changed when 0.3 wt% of the first additive is added. It is a figure which shows the capacity | capacitance retention of an element, Examples 1-3, 11-13, 21-23, 31-33, Comparative Examples 5-9, 29-33, 53-57, 77-81, 101, 102 , 115, 116, 129, 130, 143, 144 are graphs of capacity retention values.

  FIG. 3C shows the capacity of the electricity storage element when the amount of the second additive added, the type of the negative electrode active material, and the particle diameter are changed when the first additive is added by 0.5 wt%. It is a diagram showing the retention rate, Examples 4-6, 14-16, 24-26, 34-36, Comparative Examples 10-14, 34-38, 58-62, 82-86, 103, 104, 117, This is a graph of capacity retention values at 118, 131, 132, 145, and 146.

  FIG. 3D shows the capacity of the electricity storage element when the amount of the second additive added, the type of the negative electrode active material, and the particle diameter are changed when 1.0 wt% of the first additive is added. It is a figure which shows a retention rate, Examples 7-10, 17-20, 27-30, 37-40, Comparative Examples 15-21, 39-45, 63-69, 87-93, 105-107, 119- 121, 133-135, and 147-149 are graphs of capacity retention values.

  FIG. 3E shows the capacity of the electricity storage element when the amount of the second additive added, the type of the negative electrode active material, and the particle diameter are changed when the first additive is added by 1.2% by weight. It is a figure which shows a retention, and graphs the value of the capacity retention in Comparative Examples 22-24, 46-48, 70-72, 94-96, 108-110, 122-124, 136-138, 150-152 It is a thing.

  As shown in the above Table 2 and these figures, the amount of the first additive added is 0.3% by weight or more and 1.0% by weight or less of the total weight of the nonaqueous electrolytic solution, and the second Non-graphitizable with an additive addition amount of 0.05 to 0.3 times the addition amount of the first additive, and an average particle diameter D50 of 2 to 6 μm as a negative electrode active material in the negative electrode When carbon is included, the capacity retention rate is remarkably high. Thereby, reduction of the storage capacity of the storage element can be suppressed.

  When the average particle diameter D50 of the non-graphitizable carbon is smaller than 2 μm, the same effects as in the case where the average particle diameter D50 is 2 μm or more and 6 μm or less, although there are problems in productivity and cost as described above. It can be inferred that

  4A to 4E are diagrams showing the DC resistance increase rate of the electricity storage device when the addition amount of the first additive and the second additive, the type of the negative electrode active material, and the particle diameter are changed. It is.

  Specifically, FIG. 4A shows an electricity storage when the amount of the second additive added, the type of the negative electrode active material, and the particle diameter are changed when 0.2 wt% of the first additive is added. It is a figure which shows the direct current | flow resistance increase rate of an element, The direct current | flow resistance increase rate in Comparative Examples 2-4, 26-28, 50-52, 74-76, 98-100, 112-114, 126-128, 140-142 Is a graph of the value of.

Here, the horizontal axis of the graph shown in the figure shows the ratio of the added amount of the second additive (LiPF ₄ (Ox)) to the added amount of the first additive (LiPF ₂ (Ox) ₂ ). The vertical axis indicates the DC resistance increase rate.

  Similarly, FIG. 4B shows a case where the amount of the second additive added, the type of the negative electrode active material, and the particle size are changed when 0.3 wt% of the first additive is added. It is a figure which shows the direct current | flow resistance increase rate of an element, Examples 1-3, 11-13, 21-23, 31-33, Comparative Examples 5-9, 29-33, 53-57, 77-81, 101, The DC resistance increase rate values in 102, 115, 116, 129, 130, 143, and 144 are graphed.

  FIG. 4C shows the direct current of the electricity storage device when the amount of the second additive added, the type of the negative electrode active material, and the particle diameter are changed when the first additive is added by 0.5 wt%. It is a figure which shows a resistance increase rate, Examples 4-6, 14-16, 24-26, 34-36, Comparative Examples 10-14, 34-38, 58-62, 82-86, 103, 104, 117 , 118, 131, 132, 145, and 146 are graphs of DC resistance increase rates.

  FIG. 4D shows the direct current of the electricity storage element when the amount of the second additive added, the type of the negative electrode active material, and the particle diameter are changed when 1.0 wt% of the first additive is added. It is a figure which shows resistance increase rate, Examples 7-10, 17-20, 27-30, 37-40, Comparative Examples 15-21, 39-45, 63-69, 87-93, 105-107,119 -121, 133-135, the value of the direct current | flow resistance increase rate in 147-149 is graphed.

  FIG. 4E shows the direct current of the electricity storage element when the amount of the second additive added, the type of the negative electrode active material, and the particle diameter are changed when the first additive is added by 1.2 wt%. It is a figure which shows resistance increase rate, and shows the value of DC resistance increase rate in Comparative Examples 22-24, 46-48, 70-72, 94-96, 108-110, 122-124, 136-138, 150-152. It is a graph.

  As shown in the above Table 3 and these figures, the amount of the first additive added is 0.3% by weight or more and 1.0% by weight or less of the total weight of the non-aqueous electrolyte, and the second Non-graphitizable with an additive addition amount of 0.05 to 0.3 times the addition amount of the first additive, and an average particle diameter D50 of 2 to 6 μm as a negative electrode active material in the negative electrode When carbon is included, the DC resistance increase rate is remarkably low. As a result, the output of the power storage element can be increased.

  When the average particle diameter D50 of the non-graphitizable carbon is smaller than 2 μm, the same effects as in the case where the average particle diameter D50 is 2 μm or more and 6 μm or less, although there are problems in productivity and cost as described above. It can be inferred that

  As described above, according to the electricity storage device 1 according to the embodiment of the present invention, the nonaqueous electrolytic solution 6 is represented by the first additive represented by the chemical formula (5) and the chemical formula (6). A second additive, and the amount of the first additive added is 0.3 wt% or more and 1.0 wt% or less of the total weight of the non-aqueous electrolyte 6, and the second additive The addition amount of is 0.05 to 0.3 times the addition amount of the first additive. Moreover, the negative electrode of the electrical storage element 1 contains non-graphitizable carbon having an average particle diameter D50 of 6 μm or less as a negative electrode active material.

  Here, when a negative electrode active material having a small particle size is used for increasing the output of the electricity storage device, the contact area between the negative electrode active material and the non-aqueous electrolyte increases, so the reductive decomposition of the non-aqueous electrolyte The negative electrode active material deteriorates due to side reactions such as these. That is, in the negative electrode active material having a small particle size, the deterioration of the active material itself and the deterioration due to the side reaction proceed simultaneously.

  Therefore, as a result of intensive studies and examinations, the inventors of the present application, in a negative electrode active material containing non-graphitizable carbon having an average particle diameter D50 of 6 μm or less, include the first additive and the second additive. It was found that the side reaction of the nonaqueous electrolytic solution 6 can be remarkably suppressed by adding the above-described predetermined amount to the nonaqueous electrolytic solution 6. Thus, the inventors of the present application have found that, in the electricity storage device 1, performance such as high-temperature storage characteristics can be effectively improved by largely suppressing deterioration due to the side reaction of the negative electrode active material. For this reason, the electricity storage device 1 has a negative electrode active material containing non-graphitizable carbon having an average particle diameter D50 of 6 μm or less in the negative electrode, and the first additive and the second additive described above are included in the negative electrode active material. By adding the predetermined amount to the non-aqueous electrolyte 6, it is possible to increase the output and effectively improve the performance such as high-temperature storage characteristics.

  Further, non-graphitizable carbon having an average particle diameter D50 of 2 μm or more is used for the negative electrode active material of the electricity storage device 1. That is, non-graphitizable carbon having an average particle diameter D50 smaller than 2 μm is difficult to handle because the particle diameter is too small, and the production cost is increased. In addition, when the non-graphitizable carbon is applied to the negative electrode, productivity problems such as inability to apply stably occur. For this reason, productivity improvement and cost reduction can be aimed at by using the non-graphitizable carbon whose average particle diameter D50 is 2 micrometers or more.

  In addition, according to the method for manufacturing power storage device 1 according to the embodiment of the present invention, a predetermined amount of the first additive and the first additive are added to power storage device 1 including non-graphitizable carbon having an average particle diameter D50 of 6 μm or less. The nonaqueous electrolyte solution 6 to which the additive 2 is added is injected, and one or more preliminary chargings are performed before sealing. Here, the inventors of the present application perform high-temperature storage characteristics and the like by performing one or more precharges before sealing the electrolyte injection hole 31 in a state where the nonaqueous electrolyte 6 is injected into the power storage element 1. It has been found that the performance of can be effectively improved. For this reason, according to the manufacturing method of the electrical storage element 1, manufacturing the electrical storage element 1 which can improve performance, such as a high-temperature storage characteristic, effectively by performing one or more preliminary chargings before sealing. Can do.

  In addition, this invention can not only be implement | achieved as such an electrical storage element 1 or the manufacturing method of the electrical storage element 1, but the said 1st additive and a 2nd additive are added, and average particle diameter D50 is 6 micrometers. It can also be realized as a non-aqueous electrolyte 6 used in the electricity storage element 1 having a negative electrode containing the following non-graphitizable carbon as a negative electrode active material.

  The power storage device 1 and the manufacturing method thereof according to the embodiment of the present invention have been described above, but the present invention is not limited to the above-described embodiment and examples.

  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.

  INDUSTRIAL APPLICABILITY The present invention can be applied to power storage elements such as non-aqueous electrolyte secondary batteries that can achieve high output and effectively improve performance such as high-temperature storage characteristics.

DESCRIPTION OF SYMBOLS 1 Power storage element 2 Electrode body 3 Container 4 Positive electrode terminal 5 Negative electrode terminal 6 Nonaqueous electrolyte 31 Electrolyte injection hole

Claims (4)

A power storage device having a positive electrode and a negative electrode containing a substance that absorbs and releases lithium ions, and a non-aqueous electrolyte,
The non-aqueous electrolyte is
Lithium difluorobisoxalate phosphate as a first additive represented by the following chemical formula (1);
Lithium tetrafluorooxalate phosphate as a second additive represented by the following chemical formula (2),
The addition amount of the first additive is 0.3 wt% or more and 1.0 wt% or less of the total weight of the non-aqueous electrolyte, and the addition amount of the second additive is the first addition amount. 0.05 to 0.3 times the additive amount of 1 additive,
The negative electrode includes a non-graphitizable carbon having an average particle diameter D50 of 6 μm or less as a negative electrode active material.

The power storage element according to claim 1, wherein the non-graphitizable carbon has an average particle diameter D50 of 2 μm or more. A method for producing an electricity storage device having a positive electrode and a negative electrode containing a substance that absorbs and releases lithium ions, and a non-aqueous electrolyte,
Lithium difluorobisoxalate phosphate which is the first additive represented by the following chemical formula (3) and lithium tetrafluorooxalate phosphate which is the second additive represented by the following chemical formula (4) are added. An electrolyte injection step of injecting the nonaqueous electrolyte solution into the electricity storage element;
A preliminary charging step of performing at least one preliminary charging before sealing the storage element into which the nonaqueous electrolytic solution has been injected in the electrolytic solution injection step,
In the electrolytic solution injection step, the electric storage element having the negative electrode containing non-graphitizable carbon having an average particle diameter D50 of 6 μm or less as a negative electrode active material is 0.3% by weight or more of the total weight of the nonaqueous electrolytic solution. Non-aqueous electrolysis in which 1.0 wt% or less of the first additive and 0.05 to 0.3 times or less of the second additive are added. A method for manufacturing a power storage device for injecting liquid.

A non-aqueous electrolyte for a storage element having a positive electrode and a negative electrode containing a substance that absorbs and releases lithium ions,
Lithium difluorobisoxalate phosphate as a first additive represented by the following chemical formula (5);
Lithium tetrafluorooxalate phosphate as a second additive represented by the following chemical formula (6),
The addition amount of the first additive is 0.3 wt% or more and 1.0 wt% or less of the total weight of the non-aqueous electrolyte, and the addition amount of the second additive is the first addition amount. 0.05 to 0.3 times the additive amount of 1 additive,
A nonaqueous electrolytic solution used for the electricity storage device having the negative electrode containing non-graphitizable carbon having an average particle diameter D50 of 6 μm or less as a negative electrode active material.

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