WO2013047067A1

WO2013047067A1 - Non-aqueous electrolyte secondary cell

Info

Publication number: WO2013047067A1
Application number: PCT/JP2012/071877
Authority: WO
Inventors: 緑志村; 須黒　雅博
Original assignee: 日本電気株式会社
Priority date: 2011-09-26
Filing date: 2012-08-29
Publication date: 2013-04-04
Also published as: JPWO2013047067A1; JP6032205B2

Abstract

The present invention provides a non-aqueous electrolyte secondary cell having excellent cycle characteristics and storage stability. The non-aqueous electrolyte secondary cell comprises a positive electrode, a separator, a negative electrode disposed opposite the positive electrode with the separator interposed therebetween, a non-aqueous electrolyte, and a casing for housing the foregoing, wherein the negative electrode comprises a negative electrode active substance containing a metal (a) capable of forming an alloy with lithium, and a binder, and the non-aqueous electrolyte contains vinylene carbonate and a polyfunctional conjugated diene compound having two or more conjugated diene groups.

Description

Non-aqueous electrolyte secondary battery

The present invention relates to a non-aqueous electrolyte secondary battery.

Lithium secondary batteries have already been put into practical use as batteries for electronic devices such as laptop computers and mobile phones due to advantages such as high energy density, small self-discharge, and excellent long-term reliability. However, in recent years, electronic devices have been enhanced in functionality and used in electric vehicles, and development of lithium secondary batteries with higher energy density has been demanded. Therefore, the secondary battery using the graphite-based negative electrode material cannot satisfy the required characteristics.

Therefore, from the viewpoint of improving energy density, metals capable of being alloyed with lithium, such as silicon (Si) and tin (Sn), and oxides capable of inserting and extracting lithium ions have been studied as negative electrode materials.

Patent Document 1 discloses a negative electrode for a secondary battery including an active material layer including carbon material particles capable of inserting and extracting lithium ions, metal particles capable of being alloyed with lithium, and oxide particles capable of inserting and extracting lithium ions. Is described.

Patent Document 2 describes that a silicon oxide (particularly silicate) is used in a non-aqueous electrolyte secondary battery.

Patent Document 3 describes a negative electrode material for a secondary battery in which the surface of particles having a structure in which silicon microcrystals are dispersed in a silicon compound is coated with carbon.

Also, from the viewpoint of improving charge / discharge cycle characteristics and the like, a technique for coating the negative electrode or the negative electrode active material particles with a polymerizable compound has been studied.

In Patent Document 4, an active material layer containing active material particles containing silicon and / or a silicon alloy and a binder is disposed on a current collector made of a conductive metal foil, and then sintered in a non-oxidizing atmosphere. The negative electrode for lithium secondary batteries obtained is described. And in the secondary battery using this negative electrode, it is described that a film having high lithium ion conductivity is formed on the surface of the active material particles by adding vinylene carbonate as a solvent component of the nonaqueous electrolyte. Yes.

Japanese Patent No. 3982230 Japanese Patent No. 2,997,741 Japanese Patent No. 3952180 Japanese Patent No. 4033720

A secondary battery using a negative electrode active material containing a metal that can be alloyed with lithium has a problem in that the capacity is significantly reduced due to a charge / discharge cycle, and the storage stability is inferior. Cracking (miniaturization) occurs due to the volume change of the negative electrode active material due to insertion and removal of lithium ions, gas generation due to separation from the current collector and decomposition of the electrolyte on the active surface that appears newly due to the volume change, A decrease in Li ion conductivity occurs.

An object of the present invention is to provide a nonaqueous electrolyte secondary battery excellent in cycle characteristics and storage stability.

According to one embodiment of the present invention, a non-aqueous electrolyte solution including a positive electrode, a separator, a negative electrode disposed to face the positive electrode with the separator interposed therebetween, a non-aqueous electrolyte solution, and an exterior body that includes them. A secondary battery,
The negative electrode includes a negative electrode active material containing a metal (a) that can be alloyed with lithium, and a binder.
The non-aqueous electrolyte solution includes a non-aqueous electrolyte secondary battery containing vinylene carbonate and a polyfunctional conjugated diene compound having two or more conjugated diene groups.

According to another aspect of the present invention, a non-aqueous electrolysis comprising a positive electrode, a separator, a negative electrode disposed opposite to the positive electrode via the separator, a non-aqueous electrolyte, and an exterior body that contains them. A liquid secondary battery,
The negative electrode includes a negative electrode active material containing a metal (a) that can be alloyed with lithium, and a binder.
Provided is a non-aqueous electrolyte secondary battery in which a coating derived from a polyfunctional conjugated diene compound having two or more vinylene carbonates and conjugated diene groups is formed on the negative electrode surface.

According to another aspect of the present invention, a step of forming an electrode laminate including a positive electrode, a separator, and a negative electrode disposed to face the positive electrode through the separator;
Wrapping the electrode laminate with an outer package;
A step of injecting a non-aqueous electrolyte,
The negative electrode includes a negative electrode active material containing a metal (a) that can be alloyed with lithium, and a binder.
The non-aqueous electrolyte contains vinylene carbonate and a polyfunctional conjugated diene compound, and a method for producing a non-aqueous electrolyte secondary battery is provided.

According to the embodiment of the present invention, a non-aqueous electrolyte secondary battery excellent in cycle characteristics and storage stability can be provided.

1 is a schematic cross-sectional view for explaining the structure of a laminated laminate type secondary battery according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail.

A secondary battery according to an embodiment of the present invention includes a positive electrode, a separator, a negative electrode disposed to face the positive electrode with the separator interposed therebetween, a non-aqueous electrolyte, and an exterior body that contains them. This negative electrode includes a negative electrode active material containing a metal (a) that can be alloyed with lithium and a binder. As the negative electrode active material, for example, an active material containing silicon as the metal (a) can be used. For example, a laminate film can be used as the exterior body. One container including the outer package can include one or two or more pairs of positive and negative electrodes, and can have a stacked structure in which a plurality of these electrodes are stacked.

In the secondary battery according to the present embodiment, the nonaqueous electrolytic solution contains vinylene carbonate and a compound having two or more conjugated diene groups (hereinafter, appropriately referred to as “polyfunctional conjugated diene compound”). The polyfunctional conjugated diene compound can react with a film formed by the decomposition of vinylene carbonate to reinforce the film. Thereby, cycle characteristics and storage stability can be improved.

As such a non-aqueous electrolyte, a solution in which a supporting salt is dissolved in a mixed solution containing vinylene carbonate, a polyfunctional conjugated diene compound, and a non-aqueous solvent can be used.

In the secondary battery using this non-aqueous electrolyte, vinylene carbonate decomposition reaction occurs on the negative electrode surface at a base potential, and a vinylene carbonate decomposition product film is formed on the negative electrode surface. In this film, a double bond derived from vinylene carbonate remains, and this double bond can undergo Diels-Alder reaction with a conjugated diene group. Therefore, when a polyfunctional conjugated diene compound is used in combination with vinylene carbonate, a double bond derived from vinylene carbonate and a Diels-Alder reaction of the conjugated diene group occur, and the decomposition product film forms a crosslinked structure. Thus, the film is stronger than the film formed from the above, and the reaction between the active species on the surface of the lithium alloy negative electrode and the electrolytic solution can be suppressed. Furthermore, since this film is a three-dimensional crosslinked body, it is excellent in stretchability and strength. Accordingly, it is possible to follow the volume change of the lithium alloy negative electrode, and it is possible to prevent the negative electrode active material from being miniaturized. Since the thickness of the film can be controlled by the amount of vinylene carbonate and polyfunctional conjugated diene compound added, it is possible to form a very thin film having high lithium ion conductivity. With a non-aqueous electrolyte containing only vinylene carbonate or a non-aqueous electrolyte containing neither vinylene carbonate nor a polyfunctional conjugated diene compound, a coating is formed by the decomposition reaction of the non-aqueous solvent on the negative electrode surface. The coated film is brittle because it is a decomposition product of vinylene carbonate, an inorganic compound such as lithium carbonate or alkyl lithium, or a low molecular organic compound, and it is difficult to follow the volume change of the lithium alloy negative electrode. Furthermore, new active species appear due to the refinement of the active material that accompanies the insertion / extraction of lithium ions, and thus the reaction of the electrolytic solution cannot be sufficiently suppressed. Therefore, in a secondary battery using a non-aqueous electrolyte containing only vinylene carbonate or a non-aqueous electrolyte containing neither vinylene carbonate nor a polyfunctional conjugated diene compound, the coating on the negative electrode surface increases as the number of cycle tests increases. It becomes too thick and resistance increases.

The Diels-Alder reaction between the vinylene carbonate coating and the polyfunctional conjugated diene compound can occur under heating or in a high temperature environment. The temperature at that time is preferably 30 ° C. or higher, and more preferably 50 ° C. or higher. Further, this temperature is preferably 80 ° C. or less, and more preferably 70 ° C. or less, in order to suppress decomposition of the electrolytic solution and electrode deterioration. After causing the decomposition reaction of vinylene carbonate on the negative electrode surface at a base potential, heating can be performed to cause Diels-Alder reaction of polyfunctional conjugated diene groups. Alternatively, heating while applying an electric potential, that is, the decomposition reaction of vinylene carbonate and the Diels-Alder reaction of the conjugated diene group of the polyfunctional conjugated diene compound can proceed simultaneously. It is preferable that the Diels-Alder reaction of the conjugated diene group is caused by heating to form a sufficient crosslinked structure in advance. However, when a battery is used in a high temperature environment, the temperature under the environment is not required even if heating is not performed in advance. In this way, a Diels-Alder reaction of a polyfunctional conjugated diene group can be caused to form a crosslinked structure.

The polyfunctional conjugated diene compound preferably has a structure represented by the formula (1A), (1B) or (1C). In the formula, D ₁ , D ₂ , D ₃ and D ₄ each independently represent a conjugated diene group, and X 1 represents a linking group to which the conjugated diene group is bonded.

The conjugated diene group is not particularly limited, and a chain conjugated diene group and a cyclic conjugated diene group can be used, but a cyclic conjugated diene group is preferable because of excellent stability against heat and the like. Examples of the conjugated diene group include a furan ring group, a thiophene ring group, a pyrrole ring group, a cyclopentadiene ring group, a 1,3-butadienyl group, a thiophene-1-oxide ring group, and a thiophene-1,1-dioxide ring group. , Cyclopenta-2,4-dienone ring group, 2H pyran ring group, cyclohexa-1,3-diene ring group, 2H pyran 1-oxide ring group, 1,2-dihydropyridine ring group, 2H thiopyran-1,1-di Examples thereof include an oxide ring group, a cyclohexa-2,4-dienone ring group, a pyran-2-one ring group, and substituents thereof. Among these, a group having a cyclic conjugated diene structure is preferable, and a group having a heterocyclic cyclic conjugated diene structure is more preferable. As such a conjugated diene group, for example, a furan ring group can be preferably used, and as a compound having such a conjugated diene group, for example, a polyfunctional furan compound can be preferably used. The combination of conjugated diene groups may be the same or different, but polyfunctional conjugated diene compounds having the same conjugated diene group are preferable because the Diels-Alder reaction easily proceeds uniformly and a more uniform film can be formed. .

The linking group X1 linking the conjugated diene group is a polyvalent group of a saturated hydrocarbon (for example, having 1 to 12 carbon atoms) such as an acyclic alkyl group or cycloalkyl; a polyvalent group including an alkylene oxide unit such as an ethylene oxide unit or a methylene oxide unit. Polyvalent group containing an ether chain; Multivalent group of fluorinated chain saturated hydrocarbon such as a fluoroalkyl group; Multivalent group containing an amide bond; Multivalent group derived from an aromatic ring; Multivalent group containing a carbonate group Group; an ester group-containing polyvalent group; a siloxane chain-containing polyvalent group.

A polyfunctional conjugated diene compound containing a polyether chain is preferable because lithium ion conductivity is increased. A polyfunctional conjugated diene compound having an ether bond or an amide bond is preferable because lithium ion conductivity is increased by coordination with lithium ions. The polyfunctional conjugated diene compound containing a saturated hydrocarbon structure such as an alkylene group or a fluorinated hydrocarbon structure such as an aromatic ring or a fluoroalkylene group is provided with hydrophobicity on the coating film formed on the negative electrode surface. This is preferable because the effect of suppressing the reaction with the electrolytic solution is improved. A polyfunctional conjugated diene compound containing a carbonate group or an ester group is preferable because compatibility with the electrolytic solution is improved. A polyfunctional conjugated diene compound containing an ether bond, an alkyl chain, or a siloxane chain is preferable because a highly stretchable film is formed.

Polyfunctional conjugated diene compounds include difurfuryl ether, difurfuryl sulfide, difurfuryl sulfone, acetaldehyde difurfuryl mercaptal, difurfuryl persulfide, 1,2-bis (2-furyl) ethane-1,2-dione, 2 , 2 '-[(E) -1,2-ethenediyl] bisfuran, 2-hydroxy-1,2-bis (2-furanyl) ethane-1-one, cycloocta [1,2-c: 5,6-c '] Difuran, benzo [1,2-b: 5,4-b'] difuran, 1,7-dioxa-s-indacene, dimethyldiflufuryloxysilane, ethylmethyldiflufuroxysilane, diethyldiflufuroxysilane, etc. Difurans: Dimethyldifurfurylthiosilane, Ethylmethyldifurfurylthiosilane, Diethyldifurfurti Dithiosilanes such as silane; 2,5-bis [(2-furanyl) methyl] furan, methyltrifurfuryloxysilane, methyltri (3-furylmethoxy) silane, methyltri (2-furylethoxy) silane, methyltri (3-furyl) Trifurans such as ethoxy) silane, ethyltrifurfuryloxysilane, ethyltri (3-furylmethoxy) silane, ethyltri (2-furylethoxy) silane, ethyltri (3-furylethoxy) silane; tetrafurfuryloxysilane, tetra (3- Tetrasilanes such as furylmethoxy) silane, tetra (2-furylethoxy) silane, tetra (3-furylethoxy); tetrafurfurylthiosilane, tetra (3-furylmethylthio) silane, tetra (2-furylethylthio) silane, Tetra (3-F Tetrathiosilanes such as (ruethylthio) silane; 1,1′-bis (2,4-cyclopentadiene), fulvalene, 1,4-bis (2,4-cyclopentadiene-1-ylidene) cyclohexane, 2,5- And cyclodienes such as bis (2,4-cyclopentadiene-1-ylidene) hexane and 1- (2,5-hexadienyl) -1,3-cyclopentadiene.

The polyfunctional conjugated diene compound is preferably a compound having an electron donating functional group in the conjugated diene part because of the ease of Diels-Alder reaction.

The polyfunctional conjugated diene compound can be obtained by a known synthesis method. For example, a polyfunctional conjugated diene compound can be obtained by a reaction between a chloride containing a conjugated diene group and a polyol having two or more hydroxyl groups. Examples of polyols having two or more hydroxyl groups include dihydric alcohols such as ethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, and 1,6-hexanediol; glycerin, Trihydric alcohols such as trimethylolpropane, trimethylolethane, hexanetriol, castor oil; tetrahydric alcohols such as pentaerythritol, methylglycoside, diglycerin; polyglycerins such as triglycerin, tetraglycerin; dipentaerythritol, tripentaerythritol, etc. Polypentaerythritol; cycloalkane polyols such as tetrakis (hydroxymethyl) cyclohexanol; and polyvinyl alcohol. In addition, sugar alcohols such as adonitol, arabitol, xylitol, sorbitol, mannitol, iditol, tallitol, dulcitol; and sugars such as glucose, mannose glucose, mannose, fructose, sorbose, sucrose, lactose, raffinose, and cellulose. Furthermore, polyhydric phenols are mentioned. Examples of polyhydric phenols include monocyclic polyhydric phenols such as pyrogallol, hydroquinone, and phloroglucin; bisphenols such as bisphenol A and bisphenol sulfone; and phenol and formaldehyde condensates (novolac). .

Also, for example, a polyfunctional conjugated diene compound can be obtained by reacting an alcohol containing a diene group such as furfuryl alcohol or 2,4-cyclopentadien-1-ol with a polyfunctional isocyanate. The polyfunctional isocyanate has at least two isocyanate groups. Specific examples include carbodiimide-modified MDI, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, tolylene diisocyanate, naphthylene diisocyanate, lysine diisocyanate, and lysine triisocyanate.

Also, for example, a polyfunctional conjugated diene compound can be obtained by an esterification reaction between an alcohol containing a diene group and a polycarboxylic acid. Polycarboxylic acids are those having at least two carboxylic acid groups, such as oxalic acid, malonic acid, succinic acid, α-methylsuccinic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, dimerization Saturated aliphatic dicarboxylic acids such as linoleic acid; unsaturated aliphatic dicarboxylic acids such as maleic acid, mesaconic acid (methyl fumaric acid), citraconic acid (methyl maleic acid), itaconic acid (methylene succinic acid); hexahydrophthalic acid, hexa Hydroisophthalic acid, hexahydroterephthalic acid, tetrahydrophthalic acid, tetrahydroisophthalic acid, tetrahydroterephthalic acid, 4-methyltetrahydrophthalic acid, 4-methylhexahydrophthalic acid, nadic acid (bicyclo [2.2.1] hepte-5 -Ene-2,3-dicarboxylic acid), methyl nadi Cycloaliphatic dicarboxylic acids such as acid; phthalic acid, isophthalic acid, and aromatic dicarboxylic acids such as terephthalic acid.

</ RTI> By using such a polyfunctional conjugated diene compound and vinylene carbonate in combination, a three-dimensional crosslinked film can be formed on the negative electrode surface by an electropolymerization reaction, and this film is excellent in stretchability and strength.

As the content of vinylene carbonate and polyfunctional conjugated diene compound in the non-aqueous electrolyte increases, a sufficiently thick film can be formed on the electrode surface, and the decomposition reaction of the non-aqueous electrolyte on the negative electrode surface can be suppressed. This is verified by the gas generation suppression effect. On the other hand, the lower the content, the thinner the film formed on the electrode surface, so that the resistance rise can be suppressed, and the output characteristics can be improved and the cost can be reduced. From the above viewpoint, the content of vinylene carbonate and the polyfunctional conjugated diene compound in the non-aqueous electrolyte is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and more preferably 0.5% by mass or more. More preferably, 5 mass% or less is preferable, 3 mass% or less is more preferable, and 1 mass% or less is more preferable. The total content of vinylene carbonate and polyfunctional conjugated diene compound is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, further preferably 1% by mass or more, and preferably 10% by mass or less. More preferably, it is more preferably 3% by weight or less.

The blending ratio (mass ratio) of vinylene carbonate and polyfunctional conjugated diene can be set, for example, within a range of 10/1 to 1/10, and further within a range of 5/1 to 1/5. If this blending ratio is too high (the ratio of the polyfunctional conjugated diene compound is too low), crosslinking may be insufficient. If this blending ratio is too low (the ratio of the polyfunctional conjugated diene compound is too high) In addition, the polyfunctional conjugated diene compound may be excessive and increase the cost.

In the film formation, the reaction consumption rates of vinylene carbonate and polyfunctional conjugated diene compound in the nonaqueous electrolytic solution are each preferably 50% by mass or more, more preferably 70% by mass or more, and further more preferably 80% by mass or more. Preferably, 90 mass% or more is particularly preferable. As the reaction consumption rate is higher, a desired film excellent in stretchability and strength tends to be sufficiently formed on the electrode surface.

As the non-aqueous solvent, those usually used as the solvent for the non-aqueous electrolyte can be used. Specific examples thereof include carbonates, chlorinated hydrocarbons, ethers, ketones, esters, and nitriles. For example, at least one selected from non-aqueous solvents having a high dielectric constant such as ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone (GBL), and those obtained by fluorine substitution thereof, diethyl carbonate (DEC), Mixing at least one selected from non-aqueous solvents having a low dielectric constant such as dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), esters other than γ-butyrolactone, ethers, and those obtained by fluorine substitution thereof Can be used.

Examples of the supporting salt include LiPF ₆ , LiAsF ₆ , LiAlCl ₄ , LiClO ₄ , LiBF ₄ , LiSbF ₆ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , Li (CF ₃ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) A lithium salt such as ₂ . The supporting salt can be used alone or in combination of two or more.

The non-aqueous electrolyte is effective when a metal (a) that can be alloyed with lithium is used as a specific negative electrode, that is, a negative electrode active material, and in particular, occludes the metal (a) and lithium ions. It is more effective when the metal oxide (b) that can be released and the carbon material (c) that can occlude and release lithium ions are used.

The shape of the non-aqueous electrolyte secondary battery according to the present embodiment includes a cylindrical shape, a flat wound rectangular shape, a laminated rectangular shape, a coin shape, a flat wound laminated shape, and a laminated laminated shape. From the viewpoint described later, a laminated laminate type is preferable.

FIG. 1 is a schematic cross-sectional view showing an example of an electrode laminate of a laminated laminate type nonaqueous electrolyte secondary battery. In FIG. 1, the exterior body is omitted. The positive electrode 3 and the negative electrode 1 are alternately stacked via the separator 2. The positive electrode current collector 5 of each positive electrode 3 is welded to and electrically connected to each other at an end portion not covered with the positive electrode active material, and the positive electrode terminal 6 is welded to the welded portion. A negative electrode current collector 4 included in each negative electrode 1 is welded to and electrically connected to each other at an end portion not covered with the negative electrode active material, and a negative electrode terminal 7 is welded to the welded portion. This electrode laminate is housed in a container formed of a laminate film as an exterior body, and an electrolyte is injected and sealed.

A laminated battery (laminated laminated battery) having such a planar laminated structure has a smaller R portion (for example, a wound core with a wound structure) than a battery having a wound structure (winded battery). Therefore, there is an advantage that it is difficult to be adversely affected by the volume change of the electrode accompanying charging / discharging. On the other hand, since the electrode is curved in the wound type battery, the structure is easily distorted when a volume change occurs in the electrode. This is particularly noticeable when a negative electrode active material having a large volume change accompanying charge / discharge, such as a silicon-based active material, is used. Thus, as compared with a wound battery, a laminated laminate battery is suitable when an active material having a large volume change associated with charge / discharge is used. In addition, “planar laminated structure” means that each laminated electrode is a sheet-like material, and each electrode is laminated while being planar (laminated with the outer peripheral edge of the sheet-like material being the peripheral edge). It is distinguished from the structure in which the electrode laminate is bent or the structure in which the electrode laminate is wound.

However, such a laminated laminate type battery has a problem that when the gas is generated between the electrodes, the generated gas tends to stay between the electrodes. This is because in the wound battery, the distance between the electrodes is difficult to increase because tension is applied to the electrodes, whereas in the laminated laminate battery, the distance between the electrodes is likely to increase. This problem is particularly noticeable when the outer package is an aluminum laminate film. Further, when the electrolytic solution contains a carbonate ester solvent or a carboxylic acid ester solvent, this problem becomes even more remarkable.

According to the present embodiment, a long-life drive can be performed even in a laminated non-aqueous electrolyte secondary battery using a high energy negative electrode that easily generates gas.

Hereinafter, the components of the non-aqueous electrolyte secondary battery according to the present embodiment will be further described.

[1] Negative Electrode The negative electrode in the present embodiment includes a current collector and an active material layer on the current collector, and the active material layer includes a binder and a negative electrode active material. The binder binds between the active material particles and between the active material particles and the current collector.

The negative electrode active material in the present embodiment includes a metal (a) that can be alloyed with lithium, and further preferably includes a metal oxide (b) that can occlude and release lithium ions, and further occludes and releases lithium ions. It is more preferable that the carbon material (c) which can be obtained is included.

As the metal (a), Al, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn, La, or an alloy containing two or more of these is used. it can. In particular, silicon (Si) or a silicon-containing metal is preferable as the metal (a), and silicon is more preferable.

As the metal oxide (b), silicon oxide, aluminum oxide, tin oxide, indium oxide, zinc oxide, lithium oxide, or a composite oxide containing two or more of these can be used. In particular, silicon oxide is preferably included as the metal oxide (b). This is because silicon oxide is relatively stable and does not easily react with other compounds. In addition, one or more elements selected from nitrogen, boron and sulfur may be added to the metal oxide (b), for example, 0.1 to 5% by mass. By carrying out like this, the electrical conductivity of a metal oxide (b) can be improved.

The metal oxide (b) preferably has an amorphous structure in whole or in part. The metal oxide (b) having an amorphous structure can suppress the volume expansion of the carbon material (c) and the metal (a), which are other negative electrode active material components, and can suppress the decomposition of the nonaqueous electrolytic solution. Although this mechanism is not clear, it is presumed that the metal oxide (b) has an amorphous structure, so that it has some influence on the film formation at the interface between the carbon material (c) and the non-aqueous electrolyte. The amorphous structure is considered to have relatively few elements due to non-uniformity such as crystal grain boundaries and defects. It can be confirmed by X-ray diffraction measurement (general XRD measurement) that all or part of the metal oxide (b) has an amorphous structure. Specifically, when the metal oxide (b) does not have an amorphous structure, a peak specific to the metal oxide (b) is observed, but all or part of the metal oxide (b) is amorphous. When it has a structure, a peak specific to the metal oxide (b) is observed as a broad.

When the negative electrode active material contains a metal (a) and a metal oxide (b), it is preferable that the metal (a) is entirely or partially dispersed in the metal oxide (b). By dispersing at least a part of the metal (a) in the metal oxide (b), the volume expansion of the whole negative electrode can be further suppressed, and the decomposition of the non-aqueous electrolyte can also be suppressed. Note that all or part of the metal (a) is dispersed in the metal oxide (b) because of observation with a transmission electron microscope (general TEM observation) and energy dispersive X-ray spectroscopy (general). This can be confirmed by using a combination of a standard EDX measurement. Specifically, the cross section of the sample containing the metal (a) is observed, the oxygen concentration of the particles dispersed in the metal oxide (b) is measured, and the metal (a) constituting the particles is It can be confirmed that it is not an oxide.

When the negative electrode active material contains a metal (a) and a metal oxide (b), the metal oxide (b) is preferably an oxide of a metal constituting the metal (a). More preferably, the metal (a) is simple silicon and the metal oxide (b) is silicon oxide.

The negative electrode active material containing metal (a) and metal oxide (b) can be obtained, for example, by sintering metal (a) and metal oxide (b) under high temperature and reduced pressure. Or it can obtain by mixing a metal (a) and a metal oxide (b) by mechanical milling. The active material thus formed can be coated with carbon. For example, there are a method of mixing and baking this active material and an organic compound, and a method of introducing this active material into a gas atmosphere of an organic compound such as methane and performing thermal CVD.

As the carbon material (c), graphite, amorphous carbon, diamond-like carbon, carbon nanotube, or a composite containing two or more of these can be used. Here, graphite with high crystallinity has high electrical conductivity, and is excellent in adhesiveness and voltage flatness with a positive electrode current collector made of a metal such as copper. Therefore, it is advantageous in designing a secondary battery with high output and high energy. On the other hand, since amorphous carbon having low crystallinity has a relatively small volume expansion, it has a high effect of relaxing the volume expansion of the entire negative electrode, and deterioration due to non-uniformity such as crystal grain boundaries and defects hardly occurs. Therefore, it is advantageous in designing a secondary battery having a long life and high robustness.

As the negative electrode active material that is a composite of the metal (a), the metal oxide (b), and the carbon material (c), all or part of the metal oxide (b) has an amorphous structure, and the metal (a) What disperse | distributes all or one part in a metal oxide (b) can be used. Such a negative electrode active material can be produced, for example, by the method described in Patent Document 3 (Japanese Patent Laid-Open No. 2004-47404). For example, the metal oxide (b) is disproportionated at 900 to 1400 ° C. in an atmosphere containing an organic compound gas such as methane gas and a thermal CVD process is performed. Thereby, the metal element in metal oxide (b) can be clustered as a metal (a), and the composite body by which the surface was coat | covered with the carbon material (c) can be obtained. This composite can be used as a negative electrode active material.

The negative electrode active material containing the metal (a), the metal oxide (b), and the carbon material (c) can also be produced by mixing by mechanical milling.

The content of the metal (a) in the negative electrode active material is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more from the viewpoint of obtaining a sufficient addition effect (such as charge / discharge capacity). From the viewpoint of sufficiently obtaining the effect of adding other components, etc., it is preferably 95% by mass or less, more preferably 90% by mass or less, further preferably 80% by mass or less, and can also be 50% by mass or less.

The content of the metal oxide (b) in the negative electrode active material is preferably 5% by mass or more, more preferably 15% by mass or more, and further preferably 40% by mass or more from the viewpoint of charge / discharge cycle characteristics and the like. , 50% by mass or more. 90 mass% or less is preferable from the point which fully obtains the addition effect of another component, etc., 80 mass% or less is more preferable, and 70 mass% or less is further more preferable.

When the negative electrode active material contains a metal (a) and a metal oxide (b), the mass ratio (a / b) of the metal (a) and the metal oxide (b) in the negative electrode active material is not particularly limited. Can be set in the range of 5/95 to 90/10, can be set in the range of 10/90 to 80/20, and can be set in the range of 30/70 to 60/40. it can.

The content of the carbon material (c) in the negative electrode active material is preferably 1% by mass or more, more preferably 2% by mass or more from the viewpoint of obtaining a sufficient addition effect, and sufficient effects of addition of other components, etc. are obtained. From the point, 50 mass% or less is preferable and 30 mass% or less is more preferable.

When the negative electrode active material includes a metal (a), a metal oxide (b), and a carbon material (c), the ratio of the metal (a), the metal oxide (b), and the carbon material (c) is not particularly limited. Although not, it can be set according to the above range of the content. The content ratio of the metal (a) is, for example, preferably 5% by mass or more, more preferably 10% by mass or more, and 20% by mass with respect to the total of the metal (a), the metal oxide (b), and the carbon material (c). % Or more is more preferable, 90 mass% or less is preferable, 80 mass% or less is more preferable, and it can also be set to 50 mass% or less. The content ratio of the metal oxide (b) is preferably, for example, 5% by mass or more, more preferably 15% by mass or more, with respect to the total of the metal (a), the metal oxide (b), and the carbon material (c). It can also be set to 40% by mass or more, preferably 90% by mass or less, more preferably 80% by mass or less, and can also be set to 70% by mass or less. The content ratio of the carbon material (c) is, for example, preferably 1% by mass or more, more preferably 2% by mass or more, with respect to the total of the metal (a), the metal oxide (b), and the carbon material (c). 50 mass% or less is preferable and 30 mass% or less is more preferable.

The shape of the metal (a), the metal oxide (b), and the carbon material (c) is not particularly limited, but may be particulate.

The specific surface area of the negative electrode active material is preferably 0.2 m ² / g or more, more preferably 1.0 m ² / g or more, still more preferably 2.0 m ² / g or more, while 9.0 m ² / g or less. Preferably, 8.0 m ² / g or less is more preferable, and 7.0 m ² / g or less is more preferable. Here, the specific surface area is obtained by an ordinary BET specific surface area measurement method.

The average particle diameter of the negative electrode active material is preferably 0.01 μm or more, more preferably 0.1 μm or more, further preferably 0.2 μm or more, and on the other hand, 30 μm or less is more preferable, and 20 μm or less is more preferable. Here, the average particle diameter is 50% cumulative diameter D ₅₀ (median diameter), and is obtained by particle size distribution measurement by a laser diffraction scattering method.

Examples of the binder for the negative electrode include polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, styrene-butadiene copolymer rubber, polytetrafluoroethylene, polypropylene, polyethylene, Polyimide, polyamideimide, or the like can be used. Of these, polyimide or polyamideimide is preferred because of its high binding properties. The content of the binder for the negative electrode in the negative electrode is preferably 5 to 25 parts by mass, and 7 to 20 parts by mass with respect to 100 parts by mass of the negative electrode active material, from the viewpoints of binding force and energy density that are in a trade-off relationship. Is more preferable.

As the negative electrode current collector, copper, nickel, and silver are preferable in view of electrochemical stability. Examples of the shape include foil, flat plate, and mesh.

The negative electrode can be produced, for example, by forming a negative electrode active material layer containing a negative electrode active material and a negative electrode binder on a negative electrode current collector. The negative electrode active material layer can be formed by a general slurry coating method. Specifically, a negative electrode is prepared by preparing a slurry containing a negative electrode active material, a binder, and a solvent, applying the slurry onto a negative electrode current collector, drying, compressing and molding as necessary. can do. The negative electrode slurry can be obtained by dispersing and kneading the negative electrode active material in a solvent such as N-methyl-2-pyrrolidone (NMP) together with the negative electrode binder. Examples of the method for applying the negative electrode slurry include a doctor blade method, a die coater method, and a dip coating method. After forming a negative electrode active material layer in advance, a metal thin film may be formed by a method such as vapor deposition or sputtering, and this metal thin film may be used as a negative electrode current collector.

[2] Positive electrode As the positive electrode, for example, a positive electrode having a positive electrode active material layer containing a positive electrode active material and a positive electrode binder on a positive electrode current collector can be used.

As a positive electrode active material, lithium manganate having a layered structure or spinel structure such as LiMnO ₂ or Li _x Mn ₂ O ₄ (0 <x <2); a part of Mn of lithium manganate was replaced with another metal Lithium metal oxide; LiCoO ₂ , LiNiO ₂ , lithium metal oxide in which a part of these transition metals (Co, Ni) is replaced with another metal; LiNi _1/3 Co _1/3 Mn _1/3 O _2, etc. Lithium transition metal oxides whose specific transition metals do not exceed half of the total number of transition metals (atomic ratio); in these lithium transition metal oxides, lithium metal oxides containing Li in excess of the stoichiometric composition, etc. Can be mentioned. Specifically, Li _α Ni _β Co _γ Al _δ O ₂ (0.8 ≦ α ≦ 1.2, β + γ + δ = 1, 0.5 <β, 0 <γ, 0 <δ), or Li _α Ni _β Co _γ Mn _δ O ₂ (0.8 ≦ α ≦ 1.2, β + γ + δ = 1, 0.5 <β, 0 <γ, 0 <δ). In these lithium metal oxides, γ ≧ 0.1 and δ ≧ 0.01 can be set. In particular, Li _α Ni _β Co _γ Al _δ O ₂ (1 ≦ α ≦ 1.2, β + γ + δ = 1, β ≧ 0.7, γ ≦ 0.2), or Li _α Ni _β Co _γ Mn _δ O ₂ ( 1 ≦ α ≦ 1.2, β + γ + δ = 1, β ≧ 0.6, γ ≦ 0.2) are preferable. Li _α Ni _β Co _γ Mn _δ Al _ε Mg _ζ O ₂ (1 ≦ α ≦ 1.2, β + γ + δ + ε + ζ = 1, β ≧ 0.5, 0 ≦ γ ≦ 0.2, 0.01 ≦ δ ≦ 0 .49, 0 ≦ ε ≦ 0.3). A positive electrode active material can be used individually by 1 type or in combination of 2 or more types.

As the positive electrode binder, the same negative electrode binder as that used for normal negative electrodes can be used. Among these, polyvinylidene fluoride is preferable from the viewpoint of versatility and low cost. The amount of the positive electrode binder used is preferably 2 to 10 parts by mass with respect to 100 parts by mass of the positive electrode active material, from the viewpoints of binding force and energy density which are in a trade-off relationship.

As the positive electrode current collector, for example, aluminum, nickel, silver, SUS, valve metal, or an alloy thereof can be used from the viewpoint of electrochemical stability. Examples of the shape include foil, flat plate, and mesh. In particular, an aluminum foil can be preferably used.

A conductive auxiliary material may be added to the positive electrode active material layer containing the positive electrode active material for the purpose of reducing impedance. Examples of the conductive auxiliary material include carbonaceous fine particles such as graphite, carbon black, and acetylene black.

The positive electrode is prepared by, for example, preparing a slurry containing a positive electrode active material, a binder, and a solvent (and optionally a conductive auxiliary material), applying the slurry onto the positive electrode current collector, and drying the slurry. Can be produced by forming a positive electrode active material layer.

[3] Separator As the separator, a polyolefin such as polypropylene or polyethylene, a porous film or a nonwoven fabric made of a fluororesin, or the like can be used. Moreover, what laminated | stacked them can also be used as a separator.

[4] Structure of electrode pair Examples of the structure of the electrode pair include a cylindrical wound structure, a flat wound structure, a zigzag folded structure, and a laminated laminate structure, and a laminated laminate structure is particularly preferable. In the laminated laminate type structure, the electrodes and the separator are laminated in a planar shape, and there is no portion with a small R (a region close to the winding core of the wound structure or a region corresponding to the folded portion). Therefore, when an active material having a large volume change associated with charging / discharging is used, it is less likely to be adversely affected by the volume change of the electrode associated with charging / discharging than a battery having a wound structure.

[5] Exterior Body As the exterior body, a laminate film that is stable in a non-aqueous electrolyte and has a sufficient water vapor barrier property can be used. For example, as such an outer package, a laminate film such as polypropylene or polyethylene coated with aluminum or silica can be used. In particular, it is preferable to use an aluminum laminate film from the viewpoints of versatility and cost.

In the case of a non-aqueous electrolyte secondary battery that uses a laminate film as the outer package, the volume change of the battery or the distortion of the electrode due to gas generation compared to the non-aqueous electrolyte secondary battery that uses a metal can as the outer package. Is likely to occur. This is because the laminate film is more easily deformed by the internal pressure of the nonaqueous electrolyte secondary battery than the metal can. Furthermore, when sealing a non-aqueous electrolyte secondary battery using a laminate film as an outer package, the internal pressure of the battery is usually lower than atmospheric pressure and there is no extra space inside. When this occurs, it tends to immediately lead to battery volume changes and electrode deformation. The nonaqueous electrolyte secondary battery according to the present embodiment can suppress the occurrence of such a problem. Thereby, a laminated laminate type non-aqueous electrolyte secondary battery having excellent long-term reliability can be provided.

It is possible to provide an assembled battery in which a plurality of the secondary batteries (single cells) described above are electrically connected and packed with a tube or a case. The cells in the assembled battery can be connected in series, in parallel, or both. The capacity and voltage can be adjusted according to the number of cells and the connection method. A plurality of the assembled batteries can be connected in series or in parallel.

The above-mentioned secondary battery or assembled battery can be used as a power source for driving a vehicle, and can provide a vehicle with a long life and high reliability. The vehicle can be applied to a hybrid vehicle, an electric vehicle, an electric motorcycle, an electric assist bicycle, and the like. It is not limited to a four-wheel vehicle or a two-wheel vehicle, and a three-wheel vehicle is also included, and the number of wheels is not limited. Furthermore, it can be applied to various power sources for moving / transporting media such as trains.

Hereinafter, the embodiment of the present invention will be described more specifically with reference to examples.

Example 1
<Synthesis of polyfunctional conjugated diene>
After 40.0 g of furfuryl alcohol and 0.2 mL of dilaurate dibutyltin were dissolved in 150 mL of dioxane, 24.2 g of lysine triisocyanate was added dropwise. After 6 hours of reaction at 60 ° C., the solvent was distilled off under reduced pressure, and the residue was dissolved in 200 mL of chloroform. After washing with 200 mL of water three times and drying with magnesium sulfate, the solvent was distilled off under reduced pressure. The resulting crude product was recrystallized from ethyl acetate to obtain a trifunctional furan compound (2) represented by the following formula (2).

<Production of electrode>
Silicon oxide powder (mixture of silicon oxide and silicon) is subjected to CVD treatment at 1150 ° C. for 6 hours in an atmosphere containing methane gas, so that silicon in silicon oxide is nanoclustered and silicon is coated with carbon. A silicon oxide-carbon composite (negative electrode active material) was obtained. The mass ratio of silicon / silicon oxide / carbon was adjusted to be 29/61/10.

The negative electrode active material and the polyamic acid (manufactured by Ube Industries, Ltd., product) so that the mass ratio of the negative electrode active material (average particle size D ₅₀ = 5 μm) to the polyimide as the negative electrode binder is 85:15. Name: U Varnish A) was weighed and mixed with n-methylpyrrolidone to prepare a negative electrode slurry. This negative electrode slurry was applied on the surface of a copper foil having a thickness of 10 μm so as to be 2.5 mg per 1 cm ² and dried. Similarly, the negative electrode slurry was applied to the back surface of the copper foil and dried. Thereafter, heat treatment was performed at 350 ° C. in a nitrogen atmosphere, and cut into 26 mm × 65 mm to obtain a negative electrode.

Lithium nickelate (LiNi _0.80 Co _0.15 Al _0.15 O ₂ ) as a positive electrode active material, carbon black as a conductive auxiliary material, and polyvinylidene fluoride as a binder for the positive electrode, 90: A positive electrode slurry was prepared by weighing at a mass ratio of 5: 5 (active material: conductive auxiliary agent: binder) and mixing them with n-methylpyrrolidone. This positive electrode slurry was applied to the surface of an aluminum foil having a thickness of 20 μm so as to have an amount of 20 mg per cm ² , dried and pressed. Similarly, the positive electrode slurry was applied to the back surface of the aluminum foil, dried, and pressed. Then, it cut | disconnected to 23 mm x 64 mm, and the positive electrode was obtained.

1 layer of the obtained positive electrode and 2 layers of the negative electrode were alternately stacked via a polypropylene porous film (manufactured by Celgard LLC, trade name: Celgard # 2500) as a separator.

The positive electrode terminal made of aluminum is welded to the end portion of the positive electrode current collector not covered with the positive electrode active material, the end portions of the negative electrode current collector not covered with the negative electrode active material are welded to each other, and the welded portion is nickel. The manufactured negative electrode terminal was welded to obtain a planar electrode laminate.

<Preparation of electrolyte>
In a non-aqueous solvent in which EC / DEC is mixed at 3/7 (volume ratio), LiPF ₆ is dissolved so as to have a concentration of 1 mol / L. Further, vinylene carbonate as additive 1 is 1 wt%, additive 2 ( As the polyfunctional conjugated diene compound), the trifunctional furan compound (2) was dissolved to a concentration of 1 wt% to obtain a nonaqueous electrolytic solution.

<Production of cell>
The electrode laminate is wrapped with an aluminum laminate film as an outer package so that tabs (terminals) come out, and after injecting a nonaqueous electrolyte, it is sealed under reduced pressure to obtain a nonaqueous electrolyte secondary battery. It was.

<First charge>
In the first charge, in a thermostatic chamber maintained at 20 ° C., after charging at a C / 10 rate up to 4.2 V, discharge to 2.5 V at 1 C, 0.5 C, 0.2 C, and 0.1 C rates in sequence. Recharged to 4.2V at the rate.

<Heat treatment>
The initially charged battery was left for 24 hours in a constant temperature bath maintained at 60 ° C. Then, the below-mentioned 60 degreeC storage test and 60 degreeC cycle test were done.

(Example 2)
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that 1 wt% of difurfuryl ether was dissolved in place of the trifunctional furan compound (2).

(Comparative Example 1)
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that vinylene carbonate and the trifunctional furan compound (2) were not dissolved in the nonaqueous solvent.

(Comparative Example 2)
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that 2 wt% of vinylene carbonate was dissolved in the non-aqueous solvent without dissolving the trifunctional furan compound (2).

(Example 3)
A nonaqueous electrolyte secondary battery was fabricated in the same manner as in Example 1 except that no heat treatment was performed after the initial charge.

<60 ° C storage test>
The produced battery was placed in a thermostat kept at 60 ° C. and allowed to stand for one week, the volume was measured by the Archimedes method, and the volume increase rate was calculated according to the following formula and evaluated. The test results are shown in Table 1.

Volume increase rate (%) = 100 x (Volume after standing for 1 week-Initial volume) / Initial volume

Evaluation was determined according to the following criteria.
A: Volume increase rate is 30% or less,
B: Volume increase rate exceeds 30%.

<60 ° C cycle test>
The manufactured battery was subjected to a cycle test in which a charge of up to 4.2 V and a discharge of up to 2.5 V were repeated at a 1 C rate in a thermostatic chamber maintained at 60 ° C., and the capacity maintenance rate was calculated according to the following formula to evaluate went. The test results are shown in Table 1.

Capacity retention rate (%) = 100 × (discharge capacity at the 100th cycle) / (discharge capacity at the first cycle)

Evaluation was determined according to the following criteria.
A: Capacity maintenance rate exceeds 85%,
B: Capacity maintenance rate is over 80% and 85% or less,
C: Capacity maintenance rate is over 70% and 80% or less,
D: Capacity maintenance rate is 70% or less.

As shown in Table 1, the nonaqueous electrolyte secondary batteries of Examples 1 to 3 in which both vinylene carbonate (Additive 1) and the polyfunctional conjugated diene compound (Additive 2) were added to the electrolytic solution were 60 ° C. Excellent results (low volume increase rate and high capacity retention rate) were shown in the storage test and cycle test. This is a film formed by decomposing vinylene carbonate by heating at 60 ° C. after the initial charge (Examples 1 and 2) or in an environment at 60 ° C. during storage or cycling (Example 3). This is because the double bond and the conjugated diene group of the polyfunctional conjugated diene compound were subjected to Diels-Alder reaction, and the coating was strengthened to have a three-dimensional crosslinked structure.

On the other hand, Comparative Example 2 in which vinylene carbonate was added to the electrolytic solution and no polyfunctional conjugated diene compound was added had a lower volume increase rate than Comparative Example 1 in which none was added, but this volume increase rate. Is larger than Examples 1 to 3. It turns out that decomposition | disassembly of electrolyte solution cannot fully be suppressed only with vinylene carbonate.

In addition, although Example 3 showed the result (low volume increase rate and high capacity | capacitance maintenance rate) excellent compared with Comparative Example 1 and 2, volume increase rate is high compared with Example 1 and 2, and capacity maintenance. The rate is low. In Example 3, although vinylene carbonate and a polyfunctional conjugated diene compound are used in combination, since heating after the initial charge is not performed, a double bond derived from vinylene carbonate and a conjugated diene of the polyfunctional conjugated diene compound are used. This is because the electrolytic solution was decomposed before the three-dimensional crosslinked structure was sufficiently formed by the Diels-Alder reaction with the group.

From the above results, it can be seen that according to the present embodiment, a non-aqueous electrolyte secondary battery having high energy density and excellent long-term stability can be provided.

As mentioned above, although this invention was demonstrated with reference to embodiment and an Example, this invention is not limited to the said embodiment and Example. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

This application claims priority based on Japanese Patent Application No. 2011-208803 filed on September 26, 2011, the entire disclosure of which is incorporated herein.

The present embodiment can be used in all industrial fields that require a power source and industrial fields related to the transport, storage, and supply of electrical energy. Specifically, power sources for mobile devices such as mobile phones and laptop computers; power sources for electric vehicles such as electric cars, hybrid cars, electric motorcycles, electric assist bicycles, and trains; power sources for mobile and transport media such as satellites and submarines A backup power source such as a UPS (uninterruptible power supply); a power storage facility for storing power generated by solar power generation, wind power generation, or the like.

DESCRIPTION OF SYMBOLS 1 Negative electrode 2 Separator 3 Positive electrode 4 Negative electrode collector 5 Positive electrode collector 6 Positive electrode terminal 7 Negative electrode terminal

Claims

A non-aqueous electrolyte secondary battery comprising a positive electrode, a separator, a negative electrode disposed opposite to the positive electrode via the separator, a non-aqueous electrolyte, and an outer package containing them,
The negative electrode includes a negative electrode active material containing a metal (a) that can be alloyed with lithium, and a binder.
The non-aqueous electrolyte solution is a non-aqueous electrolyte secondary battery containing vinylene carbonate and a polyfunctional conjugated diene compound having two or more conjugated diene groups.
The non-aqueous electrolyte according to claim 1, wherein the content of vinylene carbonate is 0.01 to 5% by mass, and the content of the polyfunctional conjugated diene compound is 0.01 to 5% by mass. Water electrolyte secondary battery.
The nonaqueous electrolyte secondary battery according to claim 1 or 2, wherein a coating derived from the vinylene carbonate and the polyfunctional conjugated diene compound is formed on the negative electrode surface.
A non-aqueous electrolyte secondary battery comprising a positive electrode, a separator, a negative electrode disposed opposite to the positive electrode via the separator, a non-aqueous electrolyte, and an outer package containing them,
The negative electrode includes a negative electrode active material containing a metal (a) that can be alloyed with lithium, and a binder.
A non-aqueous electrolyte secondary battery in which a coating derived from a polyfunctional conjugated diene compound having two or more vinylene carbonates and conjugated diene groups is formed on the negative electrode surface.
The non-aqueous electrolyte secondary battery according to claim 4, wherein the coating has a structure formed by an addition reaction between a double bond derived from the vinylene carbonate and a conjugated diene group of the polyfunctional conjugated diene compound. .
The vinylene carbonate content is 0.01 to 5% by mass, the polyfunctional conjugated diene compound content is 0.01 to 5% by mass, and the total of the vinylene carbonate and the polyfunctional conjugated diene compound The nonaqueous electrolyte secondary battery according to any one of claims 1 to 5, which is produced using a nonaqueous electrolyte solution having a content of 0.1 to 10% by mass.
The conjugated diene groups are respectively a furan ring group, a thiophene ring group, a pyrrole ring group, a cyclopentadiene ring group, a 1,3-butadienyl group, a thiophene-1-oxide ring group, and a thiophene-1,1-dioxide ring group. , Cyclopenta-2,4-dienone ring group, 2H pyran ring group, cyclohexa-1,3-diene ring group, 2H pyran 1-oxide ring group, 1,2-dihydropyridine ring group, 2H thiopyran-1,1-di The nonaqueous electrolyte secondary solution according to any one of claims 1 to 6, comprising a group selected from the group consisting of an oxide ring group, a cyclohexa-2,4-dienone ring group, and a pyran-2-one ring group. battery.
The non-aqueous electrolyte secondary battery according to any one of claims 1 to 7, wherein the negative electrode active material contains silicon as the metal (a).
Forming an electrode laminate including a positive electrode, a separator, and a negative electrode disposed opposite to the positive electrode via the separator;
Wrapping the electrode laminate with an outer package;
A step of injecting a non-aqueous electrolyte,
The negative electrode includes a negative electrode active material containing a metal (a) that can be alloyed with lithium, and a binder.
The method for producing a non-aqueous electrolyte secondary battery, wherein the non-aqueous electrolyte contains vinylene carbonate and a polyfunctional conjugated diene compound.
The secondary battery is heated at 30 ° C. or higher and 80 ° C. or lower after initial charging or during initial charging to form a coating derived from the vinylene carbonate and the polyfunctional conjugated diene compound on the surface of the negative electrode. A method for producing the nonaqueous electrolyte secondary battery according to claim 9.