JP4573053B2 - Negative electrode and battery - Google Patents

Description

  The present invention relates to a negative electrode and a battery containing a negative electrode active material containing at least one of silicon (Si) and tin (Sn) as a constituent element.

  In recent years, many portable electronic devices such as a camera-integrated VTR (Videotape Recorder), a digital still camera, a mobile phone, a portable information terminal, or a notebook personal computer have appeared, and the size and weight of the portable electronic device have been reduced. Accordingly, development of secondary batteries that are lightweight and can obtain a high energy density as a power source for these electronic devices is underway. Among them, lithium ion secondary batteries using a carbon material for the negative electrode, a composite material of lithium (Li) and a transition metal for the positive electrode, and a carbonate ester for the electrolyte are compared with conventional lead batteries and nickel cadmium batteries. Since a large energy density can be obtained, it is widely used.

  In recent years, with the improvement in performance of portable electronic devices, further improvement in capacity has been demanded, and the use of tin or silicon instead of carbon materials as a negative electrode active material has been studied ( For example, see Patent Document 1). This is because the theoretical capacity of tin is 994 mAh / g and the theoretical capacity of silicon is 4199 mAh / g, which is much larger than the theoretical capacity of graphite, 372 mAh / g, and an improvement in capacity can be expected.

  However, since the tin alloy or silicon alloy that occludes lithium has high activity, there is a problem that the electrolytic solution is easily decomposed and lithium is inactivated. Therefore, if charging / discharging is repeated, charging / discharging efficiency will fall and sufficient cycle characteristics could not be obtained.

Therefore, it has been studied to form an inactive layer on the surface of the negative electrode active material. For example, it has been proposed to form a silicon oxide film on the surface of the negative electrode active material (see, for example, Patent Document 2). ).
U.S. Pat. No. 4,950,566 JP 2004-171874 A JP 2004-319469 A

  However, on the other hand, since the reaction resistance increases when the silicon oxide film is thickened, it has been studied that the cycle characteristics are insufficient (for example, see Patent Document 3). Therefore, in the method of forming a film made of silicon oxide on the surface of a highly active negative electrode active material, sufficient cycle characteristics cannot be obtained, and further improvement has been desired.

  This invention is made | formed in view of this problem, The objective is to provide the negative electrode which can improve charging / discharging efficiency, and a battery using the same.

  The negative electrode of the present invention has a negative electrode current collector and a negative electrode active material layer provided on the negative electrode current collector, and the negative electrode active material layer includes at least one of silicon and tin as a constituent element. The active material is contained, and the negative electrode active material has a film containing at least one oxide and halide of a group consisting of silicon, germanium (Ge), and tin on at least a part of the surface thereof. is there.

  The battery of the present invention includes an electrolyte solution together with a positive electrode and a negative electrode. The negative electrode includes a negative electrode current collector and a negative electrode active material layer provided on the negative electrode current collector. The layer contains a negative electrode active material containing at least one of silicon and tin as a constituent element, and the negative electrode active material is at least part of the surface of at least one member selected from the group consisting of silicon, germanium, and tin. And a film containing an oxide and a halide.

  According to the negative electrode of the present invention, since at least part of the surface of the negative electrode active material is provided with a film containing at least one oxide and halide of the group consisting of silicon, germanium, and tin, Chemical stability can be improved. Therefore, according to the battery using this negative electrode, charge / discharge efficiency can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
(First battery)
FIG. 1 shows a cross-sectional structure of a first secondary battery according to the first embodiment of the present invention. This secondary battery is called a so-called cylindrical type, and a winding in which a strip-like positive electrode 21 and a strip-like negative electrode 22 are laminated and wound inside a substantially hollow cylindrical battery can 11 via a separator 23. An electrode body 20 is provided. The battery can 11 is made of, for example, iron plated with nickel, and has one end closed and the other end open. An electrolyte is injected into the battery can 11 and impregnated in the separator 23. In addition, a pair of insulating plates 12 and 13 are arranged perpendicular to the winding peripheral surface so as to sandwich the winding electrode body 20.

  At the open end of the battery can 11, a battery lid 14, a safety valve mechanism 15 provided inside the battery lid 14 and a heat sensitive resistance element (Positive Temperature Coefficient; PTC element) 16 are interposed via a gasket 17. It is attached by caulking, and the inside of the battery can 11 is sealed. The battery lid 14 is made of, for example, the same material as the battery can 11. The safety valve mechanism 15 is electrically connected to the battery lid 14 via the heat sensitive resistance element 16, and the disk plate 15A is reversed when the internal pressure of the battery exceeds a certain level due to an internal short circuit or external heating. Thus, the electrical connection between the battery lid 14 and the wound electrode body 20 is cut off. When the temperature rises, the heat sensitive resistance element 16 limits the current by increasing the resistance value and prevents abnormal heat generation due to a large current. The gasket 17 is made of, for example, an insulating material, and asphalt is applied to the surface.

  For example, a center pin 24 is inserted in the center of the wound electrode body 20. A positive electrode lead 25 made of aluminum (Al) or the like is connected to the positive electrode 21 of the spirally wound electrode body 20, and a negative electrode lead 26 made of nickel or the like is connected to the negative electrode 22. The positive electrode lead 25 is electrically connected to the battery lid 14 by being welded to the safety valve mechanism 15, and the negative electrode lead 26 is welded to and electrically connected to the battery can 11.

  FIG. 2 shows an enlarged part of the spirally wound electrode body 20 shown in FIG. The positive electrode 21 has, for example, a structure in which a positive electrode active material layer 21B is provided on both surfaces of a positive electrode current collector 21A having a pair of opposed surfaces. The positive electrode current collector 21A is made of, for example, a metal material such as aluminum.

The positive electrode active material layer 21B includes, for example, one or more of positive electrode materials capable of inserting and extracting lithium as a positive electrode active material, and a conductive material such as a carbon material and polyfluoride as necessary. A binder such as vinylidene may be included. The positive electrode material capable of inserting and extracting lithium does not contain lithium such as titanium sulfide (TiS ₂ ), molybdenum sulfide (MoS ₂ ), niobium selenide (NbSe ₂ ), or vanadium oxide (V ₂ O ₂ ). Examples include chalcogenides and lithium-containing compounds containing lithium.

Among these, lithium-containing compounds are preferable because some compounds can obtain a high voltage and a high energy density. Examples of such a lithium-containing compound include a composite oxide containing lithium and a transition metal element, or a phosphoric acid compound containing lithium and a transition metal element. In particular, among cobalt, nickel, manganese, and iron What contains at least 1 sort (s) is preferable. This is because a higher voltage can be obtained. The chemical formula is represented by, for example, Lix MIO ₂ or Liy MIIPO ₄ . In the formula, MI and MII represent one or more transition metal elements. The values of x and y vary depending on the charge / discharge state of the battery, and are generally 0.05 ≦ x ≦ 1.10 and 0.05 ≦ y ≦ 1.10.

Specific examples of the composite oxide containing lithium and a transition metal element include lithium cobalt composite oxide (Li _x CoO ₂ ), lithium nickel composite oxide (Li _x NiO ₂ ), and lithium nickel cobalt composite oxide (Li _x Ni _1-Z Co _Z O ₂ (z <1)), lithium nickel cobalt manganese composite oxide (Li _X Ni _(1-VW) Co _V Mn _W O ₂ (v + w <1)), or spinel type structure Examples thereof include lithium manganese composite oxide (LiMn ₂ O ₄ ). Among these, a composite oxide containing nickel is preferable. This is because a high capacity can be obtained and excellent cycle characteristics can also be obtained. Specific examples of the phosphate compound containing lithium and a transition metal element include, for example, a lithium iron phosphate compound (LiFePO ₄ ) or a lithium iron manganese phosphate compound (LiFe _1-u Mn _u PO ₄ (u <1)). Can be mentioned.

  The negative electrode 22 has, for example, a structure in which a negative electrode active material layer 22B is provided on both surfaces of a negative electrode current collector 22A having a pair of opposed surfaces, as with the positive electrode 21. The negative electrode current collector 22A is made of, for example, a metal material such as copper.

  The negative electrode active material layer 22B contains a negative electrode active material containing at least one of silicon and tin as a constituent element. This is because silicon and tin have a large ability to occlude and release lithium, and a high energy density can be obtained.

  Examples of the negative electrode active material containing at least one of silicon and tin include, for example, a simple substance, an alloy, or a compound of silicon, a simple substance, an alloy, or a compound of tin, or one or more phases thereof. The material which has at least one part is mentioned. In the present invention, alloys include those containing one or more metal elements and one or more metalloid elements in addition to those composed of two or more metal elements. Moreover, the nonmetallic element may be included. There are structures in which a solid solution, a eutectic (eutectic mixture), an intermetallic compound, or two or more of them coexist.

  As an alloy of silicon, for example, as a second constituent element other than silicon, tin, nickel (Ni), copper (Cu), iron (Fe), cobalt (Co), manganese (Mn), zinc (Zn), Examples include those containing at least one selected from the group consisting of indium (In), silver (Ag), titanium (Ti), germanium, bismuth (Bi), antimony (Sb), and chromium (Cr). As an alloy of tin, for example, as a second constituent element other than tin, among the group consisting of silicon, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony and chromium The thing containing at least 1 sort (s) of these is mentioned.

  Examples of the silicon compound or the tin compound include those containing oxygen (O) or carbon (C), and may contain the second constituent element described above in addition to tin or silicon.

  Among them, tin, cobalt, and carbon are included as constituent elements, the carbon content is 9.9 mass% or more and 29.7 mass% or less, and the ratio of cobalt to the total of tin and cobalt Co / ( It is preferable to include a SnCoC-containing material whose Sn + Co) is 30% by mass or more and 70% by mass or less. This is because a high energy density can be obtained in such a composition range, and excellent cycle characteristics can be obtained.

  This SnCoC-containing material may further contain other constituent elements as necessary. As other constituent elements, for example, silicon, iron, nickel, chromium, indium, niobium (Nb), germanium, titanium, molybdenum (Mo), aluminum, phosphorus (P), gallium (Ga) or bismuth is preferable. It may contain more than seeds. This is because the capacity or cycle characteristics can be further improved.

  This SnCoC-containing material has a phase containing tin, cobalt, and carbon, and this phase preferably has a low crystallinity or an amorphous structure. In this SnCoC-containing material, it is preferable that at least a part of carbon that is a constituent element is bonded to a metal element or a metalloid element that is another constituent element. The decrease in cycle characteristics is thought to be due to the aggregation or crystallization of tin or the like, but this is because such aggregation or crystallization can be suppressed by combining carbon with other elements. .

  As a measuring method for examining the bonding state of elements, for example, X-ray photoelectron spectroscopy (XPS) can be cited. In XPS, the peak of the carbon 1s orbital (C1s) appears at 284.5 eV in an energy calibrated apparatus so that the peak of the gold atom 4f orbital (Au4f) is obtained at 84.0 eV if it is graphite. . Moreover, if it is surface contamination carbon, it will appear at 284.8 eV. On the other hand, when the charge density of the carbon element increases, for example, when carbon is bonded to a metal element or a metalloid element, the C1s peak appears in a region lower than 284.5 eV. That is, when the peak of the synthetic wave of C1s obtained for the SnCoC-containing material appears in a region lower than 284.5 eV, at least a part of the carbon contained in the SnCoC-containing material is a metal element or a half of other constituent elements. Combined with metal elements.

  In XPS measurement, for example, the C1s peak is used for correcting the energy axis of the spectrum. Usually, since surface-contaminated carbon exists on the surface, the C1s peak of the surface-contaminated carbon is set to 284.8 eV, and this is used as an energy standard. In the XPS measurement, the waveform of the C1s peak is obtained as a shape including the surface contamination carbon peak and the carbon peak in the SnCoC-containing material. Therefore, by analyzing using, for example, commercially available software, the surface contamination The carbon peak and the carbon peak in the SnCoC-containing material are separated. In the waveform analysis, the position of the main peak existing on the lowest bound energy side is used as the energy reference (284.8 eV).

  Such a negative electrode active material is prepared by, for example, mixing raw materials of respective constituent elements, melting them in an electric furnace, a high frequency induction furnace or an arc melting furnace, and then solidifying them, and various atomizing methods such as gas atomization or water atomization, It can be produced by various roll methods, or methods utilizing mechanochemical reactions such as mechanical alloying methods or mechanical milling methods. Especially, it is preferable to manufacture by the method using a mechanochemical reaction. This is because the negative electrode active material can have a low crystallinity or an amorphous structure. In this method, for example, a production apparatus such as a planetary ball mill apparatus or an attritor can be used.

  At least a part of the surface of the negative electrode active material includes at least one oxide selected from the group consisting of silicon, germanium, and tin, and at least one halide selected from the group consisting of silicon, germanium, and tin. A coating containing is provided. Thereby, the chemical stability of the negative electrode 22 can be improved, and the charging / discharging efficiency can be improved by suppressing the decomposition of the electrolytic solution. For example, when the negative electrode active material layer 22B is composed of a plurality of negative electrode active material particles made of the negative electrode active material described above, the coating is formed so as to cover the periphery of the negative electrode active material particles. Alternatively, it may be formed only on the surface of the negative electrode active material layer 22B, or may be formed on the surface of the negative electrode active material layer 22B and further formed between the negative electrode active material particles.

  As the halide, fluoride is preferred. This is because lithium fluoride is generated during charging and discharging and the surface of the negative electrode 22 is covered, whereby the surface of the negative electrode 22 can be further stabilized.

  Further, this film is formed by, for example, a liquid phase deposition method, an electrodeposition method, a coating method, a dip coating method, a vapor deposition method, a sputtering method, a CVD (Chemical Vapor Deposition) method or a sol-gel method. Can do.

  Especially, it is preferable to form by a liquid phase precipitation method. This is because the film can be deposited easily by controlling. In the liquid phase deposition method, for example, a dissolved species that easily coordinates fluorine (F) as an anion scavenger is added to and mixed with a solution of a fluoride complex of silicon, tin, or germanium. The formed negative electrode current collector 22A is immersed, and the fluorine anions generated from the fluoride complex are captured by the dissolved species, thereby depositing oxide and halide on the surface of the negative electrode active material layer 22B to form a film. Is the method. Instead of the fluoride complex, for example, a silicon compound, a tin compound, or a germanium compound that generates other anions such as sulfate ions may be used. Further, when the film is formed by a sol-gel method, a fluorine anion or a compound of fluorine and one of group 13 to 15 elements (specifically, fluorine ion, tetrafluoroborate ion, A treatment liquid containing hexafluorophosphate ion or the like as a reaction promoting substance may be used. This is because the coating film thus obtained has a low content of alkoxy groups and reduces the amount of gas generated when functioning as a negative electrode in an electrochemical device such as a battery.

  The negative electrode active material layer 22B may also contain other materials such as other negative electrode active materials or conductive materials in addition to the negative electrode active materials described above. Examples of the other negative electrode active material include a carbonaceous material capable of inserting and extracting lithium. This carbonaceous material is preferable because it can improve charge / discharge cycle characteristics and also functions as a conductive material. Examples of the carbonaceous material include any one of non-graphitizable carbon, graphitizable carbon, graphite, pyrolytic carbons, cokes, glassy carbons, organic polymer compound fired bodies, activated carbon and carbon black, or the like. Two or more kinds can be used. Among these, cokes include pitch coke, needle coke, and petroleum coke. Organic polymer compound fired bodies are carbonized by firing polymer compounds such as phenol resin and furan resin at an appropriate temperature. What you did. The shape of these carbonaceous materials may be any of fibrous, spherical, granular or scale-like.

  The negative electrode active material layer 22B is provided with a metal (for example, a plating film) having a metal element that does not alloy with the electrode reactant so as to be fixed to at least one of the surface of the negative electrode active material and the surface of the coating. Is preferred. Examples of the metal element here include at least one of iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), and copper (Cu).

  Such a metal can reduce the surface area of the negative electrode active material and prevent the formation of an irreversible film that can cause the progress of the electrode reaction. For example, when the negative electrode active material particles are formed by a vapor phase method or the like, fine whisker-like protrusions are formed on the surface, and thus many voids are generated between the protrusions. This void increases the surface area of the negative electrode active material, but by providing the above-mentioned metal in advance, it is generated on the surface of the negative electrode active material particles when functioning as a negative electrode in an electrochemical device such as a battery. Irreversible coating will be reduced.

  In addition, when the negative electrode active material layer 22B is composed of a plurality of negative electrode active material particles made of a negative electrode active material, it is desirable that the metal be provided in the gap between adjacent negative electrode active material particles. In this case, the metal may be provided in a gap between the negative electrode active material particles covered with the film, or may be provided in a gap between the negative electrode active material particles that are not yet covered with the film. . In the latter case, a coating may be provided so as to cover both the negative electrode active material particles and the metal filling the gaps. With such a configuration, the binding property between the negative electrode active materials is improved, and the contact between the negative electrode active material and the electrolytic solution is avoided, and the decomposition of the electrolytic solution is suppressed. Furthermore, it is desirable that the metal is filled so as to sufficiently fill the gap between the adjacent negative electrode active material particles in order to enhance the binding property. In this case, it is sufficient that a part of the gap is filled, but a larger filling amount is preferable. This is because the binding property of the negative electrode active material layer 22B is further improved.

  The negative electrode active material layer 22B has a larger formation area than the positive electrode active material layer 21B. That is, the negative electrode active material layer 22B includes a facing portion that faces the positive electrode active material layer 21B, and a surplus portion (a portion that protrudes without facing the positive electrode active material layer 21B) that surrounds the facing portion. Have. With such a configuration, the area of the negative electrode 22 that should receive the lithium ions released from the positive electrode 21 during charging is sufficiently secured, so that an increase in current density at the end of the negative electrode active material layer 22B is suppressed, Precipitation of dendritic (dendritic) metallic lithium can be avoided. Here, the coating film may be provided also on the surface of the negative electrode active material in the surplus portion of the negative electrode active material layer 22B. This is because the effects (described later) of the above-described coating film can be obtained even when the opposing positions of the positive electrode active material layer 21B and the negative electrode active material layer 22B are shifted due to repeated charge and discharge.

  The separator 23 separates the positive electrode 21 and the negative electrode 22 and allows lithium ions to pass through while preventing a short circuit of current due to contact between the two electrodes. The separator 23 is made of, for example, a porous film made of synthetic resin such as polytetrafluoroethylene, polypropylene, or polyethylene, or a porous film made of ceramic, and has a structure in which two or more kinds of porous films are laminated. It may be said. The electrolytic solution impregnated in the separator 23 includes a solvent and an electrolyte salt dissolved in the solvent.

  Examples of the solvent include ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, γ-butyrolactone, γ-valerolactone, 1,2-dimethoxyethane, tetrahydrofuran, and 2-methyl. Tetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, 1,4-dioxane, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, Methyl isobutyrate, methyl trimethylacetate, ethyl trimethylacetate, acetonitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile, N, N-dimethylformamide, N-methylpyrrolidinone, N-methyl Examples thereof include oxazolidinone, N, N'-dimethylimidazolidinone, nitromethane, nitroethane, sulfolane, trimethyl phosphate, dimethyl sulfoxide, and dimethyl sulfoxide phosphoric acid. These may be used alone or in combination of two or more. Among these, at least one selected from the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate is preferable. This is because better cycle characteristics can be obtained. In this case, in particular, a high viscosity (high dielectric constant) solvent such as ethylene carbonate or propylene carbonate (for example, a relative dielectric constant ε ≧ 30) and a low viscosity solvent such as dimethyl carbonate, ethyl methyl carbonate or diethyl carbonate (for example, , Viscosity ≦ 1 mPa · s). This is because the dissociation property of the electrolyte salt and the ion mobility are improved, so that a higher effect can be obtained.

  This solvent preferably further contains a cyclic carbonate having an unsaturated bond. This is because the decomposition reaction of the electrolytic solution containing such a solvent is further suppressed, and the cycle characteristics are further improved. Examples of the cyclic carbonate having an unsaturated bond include at least one selected from the group consisting of vinylene carbonate compounds, vinyl ethylene carbonate compounds and methylene ethylene carbonate compounds.

  Examples of the vinylene carbonate compound include vinylene carbonate (1,3-dioxol-2-one), methyl vinylene carbonate (4-methyl-1,3-dioxol-2-one), and ethyl vinylene carbonate (4-ethyl- 1,3-dioxol-2-one), 4,5-dimethyl-1,3-dioxol-2-one, 4,5-diethyl-1,3-dioxol-2-one, 4-fluoro-1,3 -Dioxol-2-one or 4-trifluoromethyl-1,3-dioxol-2-one and the like.

  Examples of the vinyl carbonate-based compound include vinyl ethylene carbonate (4-vinyl-1,3-dioxolan-2-one), 4-methyl-4-vinyl-1,3-dioxolan-2-one, and 4-ethyl. -4-vinyl-1,3-dioxolan-2-one, 4-n-propyl-4-vinyl-1,3-dioxolan-2-one, 5-methyl-4-vinyl-1,3-dioxolane-2 -One, 4,4-divinyl-1,3-dioxolan-2-one, 4,5-divinyl-1,3-dioxolan-2-one and the like.

  Examples of the methylene ethylene carbonate compound include 4-methylene-1,3-dioxolan-2-one, 4,4-dimethyl-5-methylene-1,3-dioxolan-2-one, and 4,4-diethyl-5-one. And methylene-1,3-dioxolan-2-one.

  These may be used alone or in combination of two or more. Especially, as cyclic carbonate which has an unsaturated bond, at least 1 sort (s) of the group which consists of vinylene carbonate and vinyl ethylene carbonate is preferable. This is because a sufficient effect can be obtained. In this case, vinylene carbonate is particularly preferable to vinyl ethylene carbonate. This is because a higher effect can be obtained.

  The solvent contains, for example, at least one selected from the group consisting of a chain carbonate having a halogen represented by Chemical Formula 1 as a constituent element and a cyclic carbonate having a halogen represented by Chemical Formula 7 as a constituent element. It is preferable. This is because the decomposition reaction of the electrolytic solution containing it is further suppressed, and the cycle characteristics are improved.

(R11 to R16 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, which may be the same or different from each other, but at least one of them is a halogen group or a halogenated alkyl group. is there.)

(R21 to R24 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and they may be the same or different, but at least one of them is a halogen group or a halogenated alkyl group. is there.)

  Examples of the chain carbonate having halogen as a constituent element shown in Chemical Formula 1 include fluoromethyl methyl carbonate, bis (fluoromethyl) carbonate, difluoromethyl methyl carbonate, and the like. These may be used alone or in combination of two or more.

  Examples of the cyclic carbonate having halogen as a constituent element shown in Chemical formula 2 include a series of compounds represented by Chemical formula 3 and Chemical formula 4. That is, 4-fluoro-1,3-dioxolan-2-one of (1) shown in Chemical formula 3, 4-chloro-1,3-dioxolan-2-one of (2), 4,5 of (3) -Difluoro-1,3-dioxolan-2-one, (4) tetrafluoro-1,3-dioxolan-2-one, (5) 4-fluoro-5-chloro-1,3-dioxolane-2-one ON, (6) 4,5-dichloro-1,3-dioxolan-2-one, (7) tetrachloro-1,3-dioxolan-2-one, (8) 4,5-bistrifluoromethyl 1,3-dioxolan-2-one, 4-trifluoromethyl-1,3-dioxolan-2-one of (9), 4,5-difluoro-4,5-dimethyl-1,3 of (10) -Dioxolan-2-one, 4-methyl-5,5 of (11) Difluoro-1,3-dioxolan-2-one, and the like 5,5-difluoro-1,3-dioxolan-2-one (12). In addition, 4-trifluoromethyl-5-fluoro-1,3-dioxolan-2-one of (1) shown in Chemical Formula 4, 4-trifluoromethyl-5-methyl-1,3-dioxolane of (2) 2-one, 4-fluoro-4,5-dimethyl-1,3-dioxolan-2-one of (3), 4,4-difluoro-5- (1,1-difluoroethyl)-of (4) 1,3-dioxolan-2-one, 4,5-dichloro-4,5-dimethyl-1,3-dioxolan-2-one in (5), 4-ethyl-5-fluoro-1, in (6) 3-dioxolan-2-one, 4-ethyl-4,5-difluoro-1,3-dioxolan-2-one of (7), 4-ethyl-4,5,5-trifluoro-1 of (8) , 3-Dioxolan-2-one, 4-fluoro-4-methyl-1 of (9) 3-dioxolan-2-one, and the like. These may be used alone or in combination of two or more. Among them, the cyclic carbonate having a halogen includes at least one selected from the group consisting of 4-fluoro-1,3-dioxolan-2-one and 4,5-difluoro-1,3-dioxolan-2-one. preferable. This is because it is easily available and a sufficient effect can be obtained. In this case, 4,5-difluoro-1,3-dioxolan-2-one is more preferable than 4-fluoro-1,3-dioxolan-2-one. This is because a higher effect can be obtained. Specifically, 4,5-difluoro-1,3-dioxolan-2-one is preferably a trans isomer rather than a cis isomer in order to obtain a higher effect.

  Furthermore, the solvent preferably contains, for example, sultone (cyclic sulfonic acid ester) or an acid anhydride. This is because the decomposition reaction of the electrolytic solution containing it is further suppressed, and the cycle characteristics are improved.

  Examples of sultone include propane sultone and propene sultone. These may be used alone or in combination of two or more. Among them, propene sultone is preferable as sultone. In addition, the content of sultone in the electrolytic solution is preferably in the range of 0.5 wt% to 3 wt%. This is because a sufficient effect can be obtained.

  Examples of the acid anhydride include succinic anhydride, glutaric anhydride, maleic anhydride, anhydrous sulfobenzoic acid, anhydrous sulfopropionic acid, and anhydrous sulfobutyric acid. These may be used alone or in combination of two or more. Among these, as the acid anhydride, at least one member selected from the group consisting of succinic anhydride and sulfobenzoic anhydride is preferable. This is because a sufficient effect can be obtained. In this case, sulfobenzoic anhydride is particularly preferable to succinic anhydride. This is because a higher effect can be obtained. The content of the acid anhydride in the electrolytic solution is preferably in the range of 0.5 wt% to 3 wt%. This is because a sufficient effect can be obtained.

  The electrolyte salt preferably contains, for example, at least one selected from the group consisting of compounds represented by Chemical Formula 5, Chemical Formula 6, and Chemical Formula 7. This is because sufficient conductivity can be stably obtained and cycle characteristics can be improved. The compounds shown in Chemical Formula 5 to Chemical Formula 7 may be used alone, or a plurality of types may be mixed and used.

(X31 is 1A group element or 2A group element or aluminum in the short period type periodic table. M31 is a transition metal, or 3B group element, 4B group element or 5B group element in the short period type periodic table. R31 is R31. Y31 is —OC—R32—CO—, —OC—CR33 ₂ — or —OC—CO—, wherein R32 is an alkylene group, a halogenated alkylene group, an arylene group or a halogenated arylene group. R33 is an alkyl group, a halogenated alkyl group, an aryl group or a halogenated aryl group, which may be the same or different from each other, wherein a3 is an integer of 1 to 4, and b3 is 0, or (It is an integer of 2 or 4, and c3, d3, m3 and n3 are integers of 1 to 3.)

(X41 is a Group 1A element or a Group 2A element in the short period type periodic table. M41 is a transition metal, or a Group 3B element, a Group 4B element, or a Group 5B element in the short period type periodic table. Y41 is —OC—. _{(CR41 2) b4 -CO -,} - R43 2 C- (CR42 2) c4 -CO -, - R43 2 C- (CR42 2) c4 -CR43 2 -, - R43 2 C- (CR42 2) c4 -SO ₂ —, —O ₂ S— (CR42 ₂ ) _d4 —SO ₂ — or —OC— (CR42 ₂ ) _d4 —SO ₂ —, wherein R41 and R43 are hydrogen, alkyl, halogen or halogenated Each of which may be the same as or different from each other, at least one of which is a halogen group or a halogenated alkyl group, R42 is a hydrogen group, an alkyl group A halogen group or a halogenated alkyl group, which may be the same or different from each other, wherein a4, e4 and n4 are integers of 1 or 2, b4 and d4 are integers of 1 to 4, c4 is an integer of 0 to 4, and f4 and m4 are integers of 1 to 3.)

(X51 is a group 1A element or a group 2A element in the short period type periodic table. M51 is a transition metal, or a group 3B element, a group 4B element or a group 5B element in the short period type periodic table. Rf is the number of carbon atoms = A fluorinated alkyl group having 1 to 10 carbon atoms or a fluorinated aryl group having 1 to 10 carbon atoms, Y51 is —OC— (CR51 ₂ ) _d5 —CO—, —R52 ₂ C— (CR51 ₂ ) _d5 —CO—. _{, -R52 2 C- (CR51 2)} d5 -CR52 2 -, - R52 2 C- (CR51 2) d5 -SO 2 -, - O 2 S- (CR51 2) e5 -SO 2 - or -OC- ( CR51 _{2) e5} -SO ₂ -. is, however, R51 is a hydrogen group, an alkyl group, a halogen group or a halogenated alkyl group, it is .R52 may differ and may be identical to one another hydrogen group, an alkyl group A halogen group or a halogenated alkyl group, which may be the same as or different from each other, at least one of which is a halogen group or a halogenated alkyl group, wherein a5, f5 and n5 are 1 or 2; B5, c5 and e5 are integers of 1 to 4, d5 is an integer of 0 to 4, and g5 and m5 are integers of 1 to 3.)

  As an example of the compound shown in Chemical formula 5 to Chemical formula 7, compounds represented by Chemical formula 8 and Chemical formula 9 are mentioned.

  Examples of the compound shown in Chemical formula 5 include compounds represented by Chemical formula 8 (1) to Chemical formula 8 (6).

  Examples of the compound represented by Chemical formula 6 include the compounds represented by Chemical formula 9 (1) to Chemical formula 9 (8).

Examples of the compound represented by Chemical formula 7 include the compound represented by Chemical formula 9 (9).
Is mentioned.

  These may be used alone or in combination of two or more. Especially, as a compound shown to Chemical formula 5-Chemical formula 7, the compound represented by Chemical formula 8 (6) and Chemical formula 9 (2) is preferable. This is because a sufficient effect can be obtained. Needless to say, these compounds are not limited to the compounds shown in Chemical Formula 8 or Chemical Formula 9 as long as they have the structures shown in Chemical Formulas 5 to 7.

Moreover, it is preferable that the electrolyte salt contains other electrolyte salt with the compound shown to above-mentioned Chemical formula 5-Chemical formula 7, for example. This is because a higher effect can be obtained. Other electrolyte salts include, for example, lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium perchlorate (LiClO ₄ ), lithium hexafluoroarsenate (LiAsF _6). ), Lithium tetraphenylborate (LiB (C ₆ H ₅ ) ₄ ), lithium methanesulfonate (LiCH ₃ SO ₃ ), lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ), lithium tetrachloroaluminate (LiAlCl ₄ ) And lithium hexafluorosilicate (Li ₂ SiF ₆ ), lithium chloride (LiCl), and lithium bromide (LiBr). These may be used alone or in combination of two or more. Among these, as the other electrolyte salt, at least one selected from the group consisting of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, and lithium hexafluoroarsenate is preferable. This is because a sufficient effect can be obtained. In this case, lithium hexafluorophosphate is more preferable. This is because a higher effect can be obtained because the internal resistance is lowered. In particular, the electrolyte salt may contain the compounds shown in Chemical Formulas 5 to 7 together with lithium hexafluorophosphate and the like.

  Furthermore, the electrolyte salt preferably contains, for example, compounds represented by Chemical formula 10, Chemical formula 11 and Chemical formula 12. This is because a higher effect can be obtained. These may be used alone or in combination of two or more. In particular, the electrolyte salt contains at least one selected from the group consisting of the compounds shown in Chemical Formulas 10 to 12 together with the above-described lithium hexafluorophosphate, or If the compound shown in Chemical formula 7 and the compound shown in Chemical formulas 10 to 12 are contained, higher effects can be obtained.

(M and n are integers of 1 or more, and they may be the same or different.)

(R61 is a linear or branched perfluoroalkylene group having 2 to 4 carbon atoms.)

(P, q and r are integers of 1 or more, and they may be the same or different from each other.)

Examples of the chain compound shown in Chemical formula 10 include bis (trifluoromethanesulfonyl) imide lithium (LiN (CF ₃ SO ₂ ) ₂ ), bis (pentafluoroethanesulfonyl) imide lithium (LiN (C ₂ F ₅ SO ₂ ) ₂ ), (trifluoromethanesulfonyl) (pentafluoroethanesulfonyl) imide lithium (LiN (CF ₃ SO ₂ ) (C ₂ F ₅ SO ₂ )), (trifluoromethanesulfonyl) (heptafluoropropanesulfonyl) imide lithium ( LiN (CF ₃ SO ₂ ) (C ₃ F ₇ SO ₂ )) or (trifluoromethanesulfonyl) (nonafluorobutanesulfonyl) imidolithium (LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ )) It is done. These may be used alone or in combination of two or more.

  Examples of the cyclic compound represented by Chemical Formula 11 include a series of compounds represented by Chemical Formula 13. That is, 1,2-perfluoroethanedisulfonylimide lithium of (1) shown in Chemical formula 13, 1,3-perfluoropropane disulfonylimide lithium of (2), 1,3-perfluorobutane of (3) Disulfonylimide lithium, 1,4-perfluorobutane disulfonylimide lithium of (4), and the like. These may be used alone or in combination of two or more. Among these, 1,3-perfluoropropanedisulfonylimide lithium is preferable as the cyclic compound shown in Chemical formula 11. This is because a sufficient effect can be obtained.

Examples of the chain compound shown in Chemical formula 12 include lithium tris (trifluoromethanesulfonyl) methide (LiC (CF ₃ SO ₂ ) ₃ ).

  The content of the electrolyte salt is preferably in the range of 0.3 mol / kg or more and 3.0 mol / kg or less with respect to the solvent. This is because, within such a range, higher ion conductivity can be obtained, and the capacity characteristics of the battery can be sufficiently improved.

  By using the electrolytic solution having such a configuration, the chemical stability of the electrolytic solution itself is improved, and the decomposition reaction inside the battery is suppressed.

  For example, the secondary battery can be manufactured as follows.

  First, the positive electrode 21 is produced. Specifically, first, a positive electrode active material, a conductive material, and a binder are mixed to prepare a positive electrode mixture, and this positive electrode mixture is dispersed in a solvent such as N-methyl-2-pyrrolidone. A paste-like positive electrode mixture slurry is obtained. Subsequently, the positive electrode mixture slurry is applied to the positive electrode current collector 21A and the solvent is dried. Then, the positive electrode active material layer 21B is formed by compression molding using a roll press or the like, and the positive electrode 21 is manufactured.

  Subsequently, the negative electrode 22 is produced. Specifically, first, after preparing a negative electrode mixture by mixing a negative electrode active material containing at least one of silicon and tin as a constituent element, a conductive material, and a binder, Disperse in a solvent such as N-methyl-2-pyrrolidone to obtain a paste-like negative electrode mixture slurry. Next, the negative electrode mixture slurry is applied to the negative electrode current collector 22A, dried, and compression molded to form the negative electrode active material layer 22B. Subsequently, the surface of the negative electrode active material constituting the negative electrode active material layer 22B is formed on the surface of the negative electrode active material layer 22B by the method described above, and at least one oxide selected from the group consisting of silicon, germanium, and tin, and the group consisting of silicon, germanium, and tin. The negative electrode 22 is obtained by forming a film containing at least one kind of halide.

  Here, when forming a film using the sol-gel method, it is preferable to add a compound containing tetrafluoroborate ions, hexafluorophosphate ions or fluorine ions to the treatment liquid as a reaction accelerator. By using such a reaction promoting substance, the hydrolysis reaction is promoted, the residual amount of alkoxy groups in the formed film is reduced, and as a result, gas generation inside the battery is suppressed. Specific examples of the reaction accelerator include lithium hexafluorophosphate, lithium tetrafluorophosphate, hydrofluoric acid, lithium fluoride, sodium hexafluorophosphate, sodium tetrafluorophosphate, sodium fluoride, six Examples thereof include ammonium fluorophosphate, ammonium tetrafluorophosphate, and ammonium fluoride. Moreover, as a raw material of the oxide-containing film by the sol-gel method, tetraethoxysilane, tetramethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, tetrabutoxysilane, tetra-2-methoxyethoxysilane, di-secondary (sec)- Examples include butoxyaluminoxytriethoxysilane and oligomers thereof. Alternatively, these may be mixed and used. After hydrolyzing these raw materials in a solvent such as alcohol, water, acid as a catalyst (hydrochloric acid, sulfuric acid, nitric acid, acetic acid, etc.) or alkali (ammonia, lithium hydroxide, etc.), and a reaction accelerator Then, the negative electrode is dipped and pulled up, and then dried. A series of treatments of dipping, pulling up and drying may be performed several times. Finally, a film is obtained by baking at a temperature of 150 ° C. to 1000 ° C.

  In addition, after forming a film on the surface of the negative electrode active material, or before that, a metal element that does not alloy with the electrode reactant so as to adhere to the surface of the negative electrode active material or the surface of the film using a liquid phase method or the like It is preferable to form a metal having As the metal element, at least one of iron, cobalt, nickel, zinc, and copper is used.

  After producing the positive electrode 21 and the negative electrode 22, the positive electrode lead 25 is attached to the positive electrode current collector 21A by welding or the like, and the negative electrode lead 26 is attached to the negative electrode current collector 22A by welding or the like. Subsequently, the positive electrode 21 and the negative electrode 22 are wound through the separator 23, and the tip of the positive electrode lead 25 is welded to the safety valve mechanism 15, and the tip of the negative electrode lead 26 is welded to the battery can 11. The positive electrode 21 and the negative electrode 22 are sandwiched between a pair of insulating plates 12 and 13 and stored in the battery can 11. After the positive electrode 21 and the negative electrode 22 are accommodated in the battery can 11, the electrolytic solution is injected into the battery can 11 and impregnated in the separator 23. After that, the battery lid 14, the safety valve mechanism 15, and the heat sensitive resistance element 16 are fixed to the opening end of the battery can 11 by caulking through a gasket 17. Thereby, the secondary battery shown in FIGS. 1 and 2 is completed.

  In the secondary battery, when charged, for example, lithium ions are extracted from the positive electrode 21 and inserted in the negative electrode 22 through the electrolytic solution. When discharging is performed, for example, lithium ions are released from the negative electrode 22 and inserted in the positive electrode 21 through the electrolytic solution. At this time, at least a part of the surface of the negative electrode active material has at least one oxide selected from the group consisting of silicon, germanium and tin, and at least one halogen selected from the group consisting of silicon, germanium and tin. Since the coating containing the chemical compound is provided, the chemical stability of the negative electrode 22 is improved, and the decomposition reaction of the electrolytic solution is suppressed. In addition, there is a possibility that the fluorine in the electrolytic solution may form a fluoride film on the surface of the negative electrode active material by repeatedly charging and discharging, but in that case, the electrolytic solution is formed when the coating is formed. The decomposition reaction occurs. In the present embodiment, the above-described film is formed in advance in the manufacturing stage, so that the decomposition reaction of the electrolytic solution can be suppressed from the stage of the first charge / discharge.

  As described above, according to the secondary battery of the present embodiment, at least a part of the surface of the negative electrode active material includes a coating containing at least one oxide and halide of the group consisting of silicon, germanium, and tin. Therefore, chemical stability can be improved and charge / discharge efficiency can be improved.

  In addition, after forming a film on the surface of the negative electrode active material, or before that, a metal element that does not alloy with the electrode reactant so as to adhere to the surface of the negative electrode active material or the surface of the film using a liquid phase method or the like By forming a metal having, it is possible to reduce the surface area of the negative electrode active material and to prevent the generation of an irreversible film that can cause the electrode reaction to progress.

  In particular, when the negative electrode active material layer 22B includes a plurality of negative electrode active material particles, the negative electrode active material layer 22B is adjacent to the surface of the negative electrode active material particle by using a liquid phase method or the like after or before the formation of a film. By forming a metal having a metal element that does not alloy with the electrode reactant in the gap between the negative electrode active material particles, the negative electrode active material particles are firmly bound to each other through the metal, and the negative electrode active material layer 22B Crushing and collapsing from the negative electrode current collector 22A are less likely to occur. As a result, cycle characteristics can be improved.

(Second battery)
FIG. 3 shows a configuration of the second secondary battery according to the present embodiment. This secondary battery is a so-called laminate film type, and has a wound electrode body 30 to which a positive electrode lead 31 and a negative electrode lead 32 are attached accommodated in a film-shaped exterior member 40.

  The positive electrode lead 31 and the negative electrode lead 32 are led out from the inside of the exterior member 40 to the outside, for example, in the same direction. The positive electrode lead 31 and the negative electrode lead 32 are made of, for example, a metal material such as aluminum, copper, nickel, or stainless steel, and each have a thin plate shape or a mesh shape.

  The exterior member 40 is made of, for example, a rectangular aluminum laminated film in which a nylon film, an aluminum foil, and a polyethylene film are bonded together in this order. For example, the exterior member 40 is disposed so that the polyethylene film side and the wound electrode body 30 face each other, and the outer edge portions are in close contact with each other by fusion bonding or an adhesive. An adhesive film 41 is inserted between the exterior member 40 and the positive electrode lead 31 and the negative electrode lead 32 to prevent intrusion of outside air. The adhesion film 41 is made of a material having adhesion to the positive electrode lead 31 and the negative electrode lead 32, for example, a polyolefin resin such as polyethylene, polypropylene, modified polyethylene, or modified polypropylene.

  The exterior member 40 may be made of a laminated film having another structure, a polymer film such as polypropylene, or a metal film instead of the above-described aluminum laminated film.

  FIG. 4 shows a cross-sectional structure taken along line IV-IV of the spirally wound electrode body 30 shown in FIG. The wound electrode body 30 is obtained by stacking and winding a positive electrode 33 and a negative electrode 34 with a separator 35 and an electrolyte layer 36 interposed therebetween, and the outermost peripheral portion is protected by a protective tape 37.

  The positive electrode 33 has a structure in which a positive electrode active material layer 33B is provided on both surfaces of a positive electrode current collector 33A. The negative electrode 34 has a structure in which a negative electrode active material layer 34B is provided on both surfaces of a negative electrode current collector 34A, and the negative electrode active material layer 34B and the positive electrode active material layer 33B are arranged to face each other. The configuration of the positive electrode current collector 33A, the positive electrode active material layer 33B, the negative electrode current collector 34A, the negative electrode active material layer 34B, and the separator 35 is the same as that of the positive electrode current collector 21A, positive electrode active material layer 21B, negative electrode in the first secondary battery. This is the same as the current collector 22A, the negative electrode active material layer 22B, and the separator 23.

  The electrolyte layer 36 includes an electrolytic solution and a polymer compound serving as a holding body that holds the electrolytic solution, and has a so-called gel shape. A gel electrolyte is preferable because high ion conductivity can be obtained and battery leakage can be prevented. The configuration of the electrolytic solution is the same as that of the first embodiment. Examples of the polymer compound include, for example, an ether polymer compound such as polyethylene oxide or a crosslinked product containing polyethylene oxide, an ester polymer compound such as polymethacrylate, or an acrylate polymer compound, or polyvinylidene fluoride or vinylidene fluoride. Examples thereof include polymers of vinylidene fluoride such as a copolymer with hexafluoropropylene, and any one of these or a mixture of two or more thereof is used. In particular, from the viewpoint of redox stability, it is desirable to use a fluorine-based polymer compound such as a vinylidene fluoride polymer.

  For example, the secondary battery can be manufactured as follows.

  First, a precursor solution containing an electrolytic solution, a polymer compound, and a mixed solvent is applied to each of the positive electrode 33 and the negative electrode 34 manufactured in the same manner as the positive electrode 21 and the positive electrode 22, and the mixed solvent is volatilized to form an electrolyte layer. 36 is formed. Next, the positive electrode lead 31 is attached to the positive electrode current collector 33A, and the negative electrode lead 32 is attached to the negative electrode current collector 34A. Subsequently, the positive electrode 33 and the negative electrode 34 on which the electrolyte layer 36 is formed are laminated via a separator 35 to form a laminated body, and then the laminated body is wound in the longitudinal direction, and the protective tape 37 is attached to the outermost peripheral portion. The wound electrode body 30 is formed by bonding. After that, for example, the wound electrode body 30 is sandwiched between the exterior members 40, and the outer edge portions of the exterior members 40 are sealed and sealed by thermal fusion or the like. At that time, the adhesion film 41 is inserted between the positive electrode lead 31 and the negative electrode lead 32 and the exterior member 40. Thereby, the secondary battery shown in FIGS. 3 and 4 is completed.

  Further, this secondary battery may be manufactured as follows. First, the positive electrode 33 and the negative electrode 34 are prepared as described above, and after the positive electrode lead 31 and the negative electrode lead 32 are attached to the positive electrode 33 and the negative electrode 34, the positive electrode 33 and the negative electrode 34 are stacked via the separator 35 and wound. Rotate and adhere the protective tape 37 to the outermost periphery to form a wound body that is a precursor of the wound electrode body 30. Next, the wound body is sandwiched between the exterior members 40, and the outer peripheral edge portion excluding one side is heat-sealed to form a bag shape, and is stored inside the exterior member 40. Subsequently, an electrolyte composition including an electrolytic solution, a monomer that is a raw material of the polymer compound, and other materials such as a polymerization initiator or a polymerization inhibitor as necessary is prepared, and the interior of the exterior member 40 is prepared. After the injection, the opening of the exterior member 40 is heat-sealed and sealed. Thereafter, heat is applied to polymerize the monomer to obtain a polymer compound, thereby forming the gel electrolyte layer 36, and assembling the secondary battery shown in FIGS.

  This secondary battery operates in the same manner as the first secondary battery, and can obtain the same effect.

[Second Embodiment]
The secondary battery according to the second embodiment has the same configuration, operation, and effects as those of the first embodiment except that the configurations of the negative electrodes 22 and 34 are different. Can be manufactured. Therefore, referring to FIG. 1, FIG. 2, FIG. 3 and FIG. 4, the corresponding components are denoted by the same reference numerals, and the description of the same parts is omitted.

  Similarly to the first embodiment, the negative electrodes 22 and 34 have a structure in which the negative electrode active material layers 22B and 34B are provided on both surfaces of the negative electrode current collectors 22A and 34A. As in the first embodiment, 34B contains a negative electrode active material containing at least one of silicon and tin as a constituent element, and at least part of the surface of the negative electrode active material contains silicon, A coating comprising at least one oxide from the group consisting of germanium and tin and at least one halide from the group consisting of silicon, germanium and tin is provided. Specifically, the negative electrode active material contains, for example, a simple substance, an alloy, or a compound of silicon, or a simple substance, an alloy, or a compound of tin, and may contain two or more of them.

  The negative electrode active material layers 22B and 34B are formed by using, for example, a vapor phase method, a liquid phase method, a firing method, or two or more methods thereof. The anode current collectors 22A and 34A are preferably alloyed at least at a part of the interface. Specifically, the constituent elements of the negative electrode current collectors 22A and 34A at the interface are the negative electrode active material layers 22B and 34B, the constituent elements of the negative electrode active material layers 22B and 34B are the negative electrode current collectors 22A and 34A, or Are preferably diffusing each other. Breakage due to expansion / contraction of the negative electrode active material layers 22B, 34B due to charge / discharge can be suppressed, and the electron conductivity between the negative electrode active material layers 22B, 34B and the negative electrode current collectors 22A, 34A is improved. Because it can.

  As the vapor phase method, for example, a physical deposition method or a chemical deposition method can be used. Specifically, a vacuum deposition method, a sputtering method, an ion plating method, a laser ablation method, a thermal chemical vapor deposition ( Examples include CVD (Chemical Vapor Deposition), plasma chemical vapor deposition, and thermal spraying. As the liquid phase method, a known method such as electroplating or electroless plating can be used. The firing method is, for example, a method in which a particulate negative electrode active material is mixed with a binder, dispersed in a solvent, applied, and then heat-treated at a temperature higher than the melting point of the binder. A known method can also be used for the firing method, for example, an atmospheric firing method, a reactive firing method, or a hot press firing method.

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

(Examples 1-1 to 1-7)
A coin-type secondary battery as shown in FIG. 5 was produced. This secondary battery is formed by laminating a positive electrode 51 and a negative electrode 52 via a separator 53 impregnated with an electrolytic solution, sandwiching between an outer can 54 and an outer cup 55 and caulking via a gasket 56. is there.

  First, silicon was deposited on a negative electrode current collector 52A made of a copper foil having a thickness of 10 μm by an electron beam evaporation method to form a negative electrode active material layer 52B, and then punched into a pellet having a diameter of 16 mm.

Subsequently, in Examples 1-1 to 1-5, the negative electrode current collector 52A on which the negative electrode active material layer 52B was formed was dissolved in hydrofluoric acid as a fluoride complex with boric acid as an anion scavenger. The film containing silicon oxide (SiO ₂ ) and silicon fluoride was deposited on the surface of the negative electrode active material made of silicon by being immersed in the solution. At that time, the concentration of silicic hydrofluoric acid and boric acid, respectively 2 mol / dm ^3, was 0.028 mol / dm ^3. The immersion time was 1 hour in Example 1-1, 2 hours in Example 1-2, 3 hours in Example 1-3, 6 hours in Example 1-4, and Example 1- 5 was 21 hours. After that, the negative electrode 52 was manufactured by washing with water and drying under reduced pressure.

In Example 1-6, the negative electrode current collector 52A on which the negative electrode active material layer 52B is formed is immersed in a solution in which aluminum chloride as an anion scavenger is dissolved in tin hydrofluoric acid as a fluoride complex. Thus, a film containing tin oxide and tin fluoride was deposited on the surface of the negative electrode active material made of silicon. At that time, the concentration of tin hydrofluoric acid and aluminum chloride, respectively 0.17 mol / dm ^3, and 0.07 mol / dm ^3, the immersion time was 3 hours. After that, the negative electrode 52 was manufactured by washing with water and drying under reduced pressure.

Further, in Example 1-7, the negative electrode current collector 52A on which the negative electrode active material layer 52B was formed was immersed in a solution in which aluminum chloride as an anion scavenger was dissolved in germanium hydrofluoric acid as a fluoride complex. As a result, a film containing germanium oxide and germanium fluoride was deposited on the surface of the negative electrode active material made of silicon. At that time, the concentration of germanium hydrofluoric acid and aluminum chloride, respectively 0.17 mol / dm ^3, and 0.05 mol / dm ^3, the immersion time was 3 hours. After that, the negative electrode 52 was manufactured by washing with water and drying under reduced pressure.

  The ratio of the element in a film was calculated | required by XPS using the produced negative electrode 52. FIG. The results are shown in Table 1.

Also, lithium carbonate (Li ₂ CO ₃ ) and cobalt carbonate (CoCO ₃ ) are mixed at a molar ratio of Li ₂ CO ₃ : CoCO ₃ = 0.5: 1, and calcined in air at 900 ° C. for 5 hours. Lithium / cobalt composite oxide (LiCoO ₂ ) as a positive electrode active material was obtained. Next, 91 parts by mass of this lithium-cobalt composite oxide, 6 parts by mass of graphite as a conductive material, and 3 parts by mass of polyvinylidene fluoride as a binder were prepared to prepare a positive electrode mixture, and then N as a solvent. -Dispersed in methyl-2-pyrrolidone to obtain a positive electrode mixture slurry. Subsequently, the positive electrode mixture slurry was uniformly applied to a positive electrode current collector 51A made of an aluminum foil having a thickness of 20 μm, dried, and then compression molded to form a positive electrode active material layer 51B. After that, the positive electrode 51 was produced by punching into a pellet having a diameter of 15.5 mm.

Next, the prepared positive electrode 51 and negative electrode 52 are placed on the outer can 54 via a separator 53 made of a microporous polypropylene film, and an electrolytic solution is injected thereon, and the outer cup 55 is covered and caulked. Was sealed. In the electrolytic solution, 4-fluoro-1,3-dioxolan-2-one and diethyl carbonate as a solvent are mixed at a mass ratio of 1: 1, and lithium hexafluorophosphate as an electrolyte salt is 1 mol / dm. What was dissolved at a concentration of ³ was used.

  As Comparative Example 1-1 with respect to Examples 1-1 to 1-7, except that a film containing silicon, germanium, or tin oxide and fluoride was not formed, Example 1-1 to 1 were otherwise used. A secondary battery was fabricated in the same manner as in -7. Further, as Comparative Example 1-2, a negative electrode current collector was formed by depositing silicon by an electron beam vapor deposition method to form a negative electrode active material layer, and then a coating made of silicon oxide by a vapor phase method on the surface of the negative electrode active material layer A secondary battery was fabricated in the same manner as in Examples 1-1 to 1-7, except that the negative electrode on which was formed was used.

The cycle characteristics of the fabricated secondary batteries of Examples 1-1 to 1-7 and Comparative Examples 1-1 and 1-2 were examined. As for the cycle characteristics, 100 cycles of charge and discharge were performed at 23 ° C., and the discharge capacity retention rate (%) at the 100th cycle when the discharge capacity at the second cycle was set to 100 was obtained. In that case, charging, after performing a constant current density of 1 mA / cm ² until the battery voltage reached 4.2V, performed at a constant voltage of 4.2V until the current density reached 0.02 mA / cm ^2, discharge Was performed at a constant current density of 1 mA / cm ² until the battery voltage reached 2.5V. The results are shown in Table 1.

  As shown in Table 1, according to the results of XPS, in Examples 1-1 to 1-5, silicon, oxygen, and fluorine were confirmed, and it was confirmed that silicon oxide and a fluoride of silicon were present. . In Example 1-6, oxygen, fluorine, and tin were confirmed, and the presence of tin oxide and tin fluoride was confirmed. Furthermore, in Example 1-7, oxygen, fluorine, and germanium were confirmed, and it was confirmed that germanium oxide and germanium fluoride were present.

  Further, a film containing silicon oxide and silicon fluoride, a film containing tin oxide and tin fluoride, or a film of germanium oxide and germanium on the surface of the negative electrode active material made of silicon. According to Examples 1-1 to 1-7 in which a film was formed from the chemical compound, the discharge capacity retention ratio was improved as compared with Comparative Examples 1-1 and 1-2 in which such a film was not formed.

  That is, if at least part of the surface of the negative electrode active material containing silicon as a constituent element is provided with a film containing at least one oxide and halide of the group consisting of silicon, germanium and tin, It was found that cycle characteristics can be improved.

(Examples 2-1 to 2-5)
First, 90% by mass of silicon powder having an average particle diameter of 1 μm as a negative electrode active material and 10% by mass of polyvinylidene fluoride as a binder are mixed and dispersed in N-methyl-2-pyrrolidone as a solvent to form a negative electrode. A mixture slurry was obtained. Subsequently, the negative electrode mixture slurry was uniformly applied to a negative electrode current collector 52A made of a copper foil having a thickness of 18 μm, dried and pressurized, and then heated at 400 ° C. for 12 hours in a vacuum atmosphere, thereby An active material layer 52B was formed and punched into a pellet having a diameter of 16 mm. Subsequently, the negative electrode current collector 52A on which the negative electrode active material layer 52B was formed was immersed in a solution obtained by dissolving boric acid in hydrofluoric acid similar to Examples 1-1 to 1-5. A film containing silicon oxide (SiO ₂ ) and silicon fluoride was deposited on the surface of the negative electrode active material. At that time, the immersion time was 1 hour in Example 2-1, 2 hours in Example 2-2, 3 hours in Example 2-3, 6 hours in Example 2-4, and Example 2 In -5, it was 21 hours. After that, the negative electrode 52 was manufactured by washing with water and drying under reduced pressure.

  After producing the negative electrode 52, the secondary battery was produced using this negative electrode 52 like Example 1-1 to 1-5.

  As Comparative Example 2-1 with respect to Examples 2-1 to 2-5, except that a film containing a silicon oxide and a silicon fluoride was not formed, the others were Examples 2-1 to 2-5. A secondary battery was fabricated in the same manner as described above. Further, as Comparative Example 2-2, except that a negative electrode in which a surface of a silicon powder having an average particle diameter of 1 μm was oxidized by heating to 1000 ° C. in air to form a film made of silicon oxide was used. Produced secondary batteries in the same manner as in Examples 2-1 to 2-5.

  For the fabricated secondary batteries of Examples 2-1 to 2-5 and Comparative examples 2-1 and 2-2, cycle characteristics were examined in the same manner as in Examples 1-1 to 1-7. The results are shown in Table 2.

  As shown in Table 2, the same results as in Examples 1-1 to 1-5 were obtained. That is, if at least part of the surface of the negative electrode active material containing silicon as a constituent element is provided with a film containing at least one oxide and halide of the group consisting of silicon, germanium and tin, It was found that the cycle characteristics can be improved even if the method for forming the negative electrode active material layer 52B is changed.

(Examples 3-1 to 3-3)
80 parts by mass of SnCoC-containing material as a negative electrode active material, 11 parts by mass of graphite and 1 part by mass of acetylene black as a conductive material, and 8 parts by mass of polyvinylidene fluoride as a binder are mixed, and N-methyl-2 as a solvent -Dispersed in pyrrolidone to make a negative electrode mixture slurry. Subsequently, the negative electrode mixture slurry is uniformly applied to a negative electrode current collector 52A made of a copper foil having a thickness of 10 μm and dried, followed by compression molding to form a negative electrode active material layer 52B, which is punched into a pellet having a diameter of 16 mm. It was. Subsequently, the negative electrode current collector 52A on which the negative electrode active material layer 52B is formed is immersed in a solution obtained by dissolving boric acid in hydrofluoric acid similar to those in Examples 1-1 to 1-5, thereby SnCoC. A film containing silicon oxide (SiO ₂ ) and silicon fluoride was deposited on the surface of the negative electrode active material made of the containing material. At that time, the concentrations of silicofluoric acid and boric acid were 0.1 mol / l and 0.028 mol / l, respectively. The immersion time was 1 hour in Example 3-1, 3 hours in Example 3-2, and 6 hours in Example 3-3. After that, the negative electrode 52 was manufactured by washing with water and drying under reduced pressure.

  The SnCoC-containing material was synthesized using a mechanochemical reaction by mixing tin / cobalt / indium alloy powder and carbon powder. When the composition of the obtained SnCoC-containing material was analyzed, the tin content was 48 mass%, the cobalt content was 23 mass%, the carbon content was 20 mass%, and the cobalt relative to the total of tin and cobalt The ratio Co / (Sn + Co) was 32.4% by mass. The carbon content was measured by a carbon / sulfur analyzer, and the tin and cobalt contents were measured by ICP (Inductively Coupled Plasma) emission analysis. Further, when X-ray diffraction was performed on the obtained SnCoC-containing material, a diffraction peak having a wide half-width with a diffraction angle 2θ of 1.0 ° or more was observed between the diffraction angle 2θ = 20 ° and 50 °. It was. Further, when XPS was performed on this SnCoC-containing material, a peak P1 was obtained as shown in FIG. When the peak P1 was analyzed, a peak P2 of surface contamination carbon and a peak P3 of C1s in the SnCoC-containing material on the lower energy side than the peak P2 were obtained. This peak P3 was obtained in a region lower than 284.5 eV. That is, it was confirmed that carbon in the SnCoC-containing material was bonded to other elements.

  After producing the negative electrode 52, the secondary battery was produced using this negative electrode 52 like Example 1-1 to 1-5.

  As Comparative Example 3-1 with respect to Examples 3-1 to 3-3, except that a film containing a silicon oxide and a silicon fluoride was not formed, the others were Examples 3-1 to 3-3. A secondary battery was fabricated in the same manner as described above.

  For the fabricated secondary batteries of Examples 3-1 to 3-3 and Comparative example 3-1, cycle characteristics were examined in the same manner as in Examples 1-1 to 1-7. The results are shown in Table 3.

  As shown in Table 3, the same results as in Examples 1-1 to 1-5 were obtained. That is, if at least a part of the surface of the negative electrode active material containing tin as a constituent element is provided with a film containing at least one oxide and halide of the group consisting of silicon, germanium and tin, It was found that cycle characteristics can be improved.

(Examples 4-1 to 4-3)
The cylindrical secondary battery shown in FIGS. At that time, the positive electrode 21 and the negative electrode 22 were produced in the same manner as in Examples 1-1, 1-3, and 1-4. The negative electrode 22 is obtained by forming a negative electrode active material layer 22B made of silicon by an electron beam evaporation method and then forming a film containing silicon oxide and silicon fluoride. Further, a microporous polypropylene film having a thickness of 25 μm was used for the separator 23, and the electrolytic solution was the same as in Examples 1-1 to 1-7.

  Moreover, the ratio of the element in a film was calculated | required by XPS using the produced negative electrode 22. FIG. The results are shown in Table 4.

  As Comparative Example 4-1 with respect to Examples 4-1 to 4-3, except that a film containing a silicon oxide and a silicon fluoride was not formed, the others were Examples 4-1 to 4-3. A secondary battery was fabricated in the same manner as described above.

  For the fabricated secondary batteries of Examples 4-1 to 4-3 and Comparative example 4-1, cycle characteristics were examined in the same manner as in Examples 1-1 to 1-7. The results are shown in Table 4.

  As shown in Table 4, the same results as in Examples 1-1 to 1-5 were obtained. That is, even in the case of a secondary battery having another shape, at least part of the surface of the negative electrode active material containing at least one of silicon and tin as a constituent element is selected from the group consisting of silicon, germanium, and tin. It has been found that cycle characteristics can be improved by providing a film containing at least one oxide and a halide.

(Examples 5-1 to 5-3)
The laminate film type secondary battery shown in FIGS. First, the positive electrode 33 and the negative electrode 34 were produced like Example 1-1, 1-3, 1-4. The negative electrode 34 is obtained by forming a negative electrode active material layer 34B made of silicon by an electron beam vapor deposition method and then forming a film containing silicon oxide and silicon fluoride. Moreover, the ratio of the element in a film was calculated | required by XPS using the produced negative electrode 34. FIG. The results are shown in Table 5.

  Next, 4-fluoro-1,3-dioxolan-2-one as a solvent and propylene carbonate are mixed at a mass ratio of 1: 1, and lithium hexafluorophosphate as an electrolyte salt is dissolved at a concentration of 1 mol / l. To prepare an electrolyte solution. Subsequently, a polymer obtained by block copolymerization of vinylidene fluoride and hexafluoropropylene at a mass ratio of vinylidene fluoride: hexafluoropropylene = 93: 7 as a polymer compound was prepared. The prepared electrolytic solution was mixed with a mixed solvent to prepare a precursor solution. After that, the prepared precursor solution was applied to each of the positive electrode 33 and the negative electrode 34, and the mixed solvent was volatilized to form a gel electrolyte layer 36.

  Next, the positive electrode lead 31 made of aluminum is attached to the positive electrode 33, the negative electrode lead 32 made of nickel is attached to the negative electrode 34, and the positive electrode 33 and the negative electrode 34 are laminated via a separator 35 made of polyethylene having a thickness of 25 μm. After that, a secondary battery was produced by enclosing the outer member 40 made of a laminate film under reduced pressure.

  As Comparative Example 5-1 with respect to Examples 5-1 to 5-3, except that a film containing an oxide of silicon and a fluoride of silicon was not formed, other examples 5-1 to 5-3 A secondary battery was fabricated in the same manner as described above.

  For the fabricated secondary batteries of Examples 5-1 to 5-3 and Comparative example 5-1, cycle characteristics were examined in the same manner as in Examples 1-1 to 1-7. The results are shown in Table 5.

  As shown in Table 5, the same results as in Examples 1-1 to 1-5 were obtained. That is, even when a gel electrolyte is used, at least a part of the surface of the negative electrode active material containing at least one of silicon and tin as a constituent element is at least one of the group consisting of silicon, germanium, and tin. It was found that the cycle characteristics can be improved by providing a film containing a seed oxide and a halide.

(Examples 6-1 to 6-11)

First, the positive electrode 33 was produced. That is, lithium carbonate (Li ₂ CO ₃ ) and cobalt carbonate (CoCO ₃ ) are mixed at a molar ratio of Li ₂ CO ₃ : CoCO ₃ = 0.5: 1, and calcined in air at 900 ° C. for 5 hours. Lithium / cobalt composite oxide (LiCoO ₂ ) as a positive electrode active material was obtained. Next, 91 parts by mass of this lithium-cobalt composite oxide, 6 parts by mass of graphite as a conductive material, and 3 parts by mass of polyvinylidene fluoride as a binder were prepared to prepare a positive electrode mixture, and then N as a solvent. -Dispersed in methyl-2-pyrrolidone to obtain a positive electrode mixture slurry. Subsequently, the positive electrode mixture slurry is uniformly applied to both surfaces of a positive electrode current collector 33A made of an aluminum foil having a thickness of 12 μm, dried, and then compression-molded with a roll press to form a positive electrode active material layer 33B. did. After that, the positive electrode lead 31 made of aluminum was welded and attached to one end of the positive electrode current collector 33A.

Next, the negative electrode 34 was produced. Specifically, first, a plurality of negative electrode active material particles made of silicon are formed on a negative electrode current collector 34A made of a copper foil having a thickness of 10 μm by an electron beam evaporation method, and silicon oxide and silicon oxide are formed on the surface of the negative electrode active material particles. A negative electrode active material layer 34B was obtained by selectively forming a film containing a silicon fluoride. The coating was formed using the sol-gel method in Examples 6-1 to 6-9. In performing the sol-gel method, first, 25 g of tetraethoxy was added to a solution in which 75.2 g of ethanol, 23.5 g of water, 0.3 g of hydrochloric acid, and 0.9 g of lithium hexafluorophosphate were mixed. Silane was added and stirred for 2 hours to produce a treatment solution. Subsequently, the negative electrode current collector 34A on which the negative electrode active material layer 34B is formed is immersed in this treatment solution, pulled up from the treatment solution, and sufficiently evaporated a solvent such as ethanol, and then at 200 ° C. for 1 hour. Baked. On the other hand, in Examples 6-10 and 6-11, a film was formed by the liquid phase precipitation method in the same manner as in Example 1-3. The thickness of the coating was adjusted to fall within the range of 30 nm to 300 nm. Furthermore, in Examples 6-9 and 6-11, cobalt was deposited by an electrolytic plating method while supplying air to the plating bath so as to fill the gaps between the negative electrode active material particles covered with the coating film. At this time, a cobalt plating solution manufactured by Japan High Purity Chemical Co., Ltd. was used as the plating solution, the current density was 2 A / dm ^{2 to} 5 A / dm ² , and the plating rate was 10 nm / second. Finally, a nickel negative electrode lead 32 was attached to one end of the negative electrode current collector 34A.

  Subsequently, as a solvent, various additives shown in Table 6 (described later) are mixed with the main agent in which ethylene carbonate (EC) and diethyl carbonate (DEC) are mixed at a mass ratio of 1: 1. After preparing what was mixed each, the electrolyte solution was produced by dissolving lithium hexafluorophosphate as an electrolyte salt at a concentration of 1 mol / kg in this solvent. However, no additive was added in Example 6-1. In Table 6, VC is vinylene carbonate (1,3-dioxol-2-one), VEC is vinyl ethylene carbonate (4-vinyl-1,3-dioxolan-2-one), and FEC is fluoro. Ethylene carbonate (4-fluoro-1,3-dioxolan-2-one), DFEC is difluoroethylene carbonate (4,5-difluoro-1,3-dioxolan-2-one), and PRS is propene sultone. Yes, SCAH is succinic anhydride, and SBAH is anhydrous sulfobenzoic acid. After preparing the electrolytic solution, a polymer prepared by block copolymerization of vinylidene fluoride and hexafluoropropylene at a mass ratio of vinylidene fluoride: hexafluoropropylene = 93: 7 as a polymer compound was prepared. The compound and the previously prepared electrolyte were mixed using a predetermined mixed solvent to prepare a precursor solution. After that, the prepared precursor solution was applied to each of the positive electrode 33 and the negative electrode 34, and the mixed solvent was volatilized to form a gel electrolyte layer 36.

  Next, the positive electrode 33 and the negative electrode 34 were laminated and wound via a separator 35 made of polyethylene having a thickness of 25 μm, and then enclosed in an exterior member 40 made of a laminate film under reduced pressure to produce a secondary battery.

(Comparative Examples 6-1 to 6-3)
Further, as Comparative Example 6-1, a secondary battery was fabricated in the same manner as Example 6-1 except that no coating was provided, and as Comparative Example 6-2, no coating was provided. Other than that, a secondary battery was fabricated in the same manner as in Examples 6-5 and 6-10, and as Comparative Example 6-3, except that no coating was provided, Examples 6-9 and 6-6 were the same. In the same manner as in Example 11, a secondary battery was produced.

The cycle characteristics of the fabricated secondary batteries of Examples 6-1 to 6-11 and Comparative Examples 6-1 to 6-3 were examined. As for the cycle characteristics, 100 cycles of charge and discharge were performed at 23 ° C., and the discharge capacity retention rate (%) at the 100th cycle when the discharge capacity at the second cycle was set to 100 was obtained. In that case, charging, after performing a constant current density of 1 mA / cm ² until the battery voltage reached 4.2V, performed at a constant voltage of 4.2V until the current density reached 0.02 mA / cm ^2, discharge Was performed at a constant current density of 1 mA / cm ² until the battery voltage reached 2.5V. Moreover, about the produced negative electrode 34, the ratio of the element in a film was calculated | required by XPS. The results are shown in Table 6.

  As shown in Table 6, according to the results of XPS, in Examples 6-1 to 6-11, silicon, oxygen, and fluorine were confirmed, and it was confirmed that silicon oxide and a fluoride of silicon were present. . Furthermore, it was found that the cycle characteristics were improved by forming a film containing silicon oxide and silicon fluoride on the surface of the negative electrode active material particles using the sol-gel method or the liquid phase precipitation method. Further, by comparing Example 6-5 with Example 6-9, or comparing Example 6-10 with Example 6-11, the electrode reactant was alloyed with the gap between the adjacent negative electrode active material particles. It was confirmed that the cycle characteristics were further improved by filling a metal having a metal element that was not used. Furthermore, by comparing Examples 6-9 and 6-11 with Comparative Example 6-3, it was confirmed that the cycle characteristics were further improved by filling the above-mentioned metal together with the formation of the film.

(Example 7-1)
Except that LiPF ₆ and LiBF ₄ were dissolved in an electrolyte solution at concentrations of 0.9 mol / kg and 0.1 mol / kg, respectively, as the electrolyte salt, Example 6-1 and others were used. Similarly, a secondary battery of Example 7-1 was produced.

(Example 7-2)
Except that LiPF ₆ and the compound shown in Chemical Formula 8 (6) were dissolved in the electrolyte solution at concentrations of 0.9 mol / kg and 0.1 mol / kg, respectively, as the electrolyte salt, Otherwise, the secondary battery of Example 7-2 was produced in the same manner as Example 6-1.

(Example 7-3)
Except that LiPF ₆ and the compound shown in Chemical Formula 9 (2) were dissolved in the electrolyte at concentrations of 0.9 mol / kg and 0.1 mol / kg, respectively, as the electrolyte salt, Otherwise, the secondary battery of Example 7-3 was produced in the same manner as Example 6-1.

(Example 7-4)
Except that LiPF ₆ and the compound shown in chemical formula 13 (2) were dissolved in the electrolyte at concentrations of 0.9 mol / kg and 0.1 mol / kg, respectively, as the electrolyte salt, Otherwise, the secondary battery of Example 7-4 was produced in the same manner as Example 6-1.

(Example 7-5)
As the electrolyte salt, LiPF ₆ , the compound shown in Chemical formula 8 (6) and the compound shown in Chemical formula 13 (2) are respectively 0.9 mol / kg, 0.05 mol / kg and 0.05 mol / kg with respect to the electrolytic solution. A secondary battery of Example 7-5 was made in the same manner as Example 6-1 except that the material dissolved at a concentration of 5 was used.

  Further, as Comparative Example 7-1, a secondary battery was fabricated in the same manner as in Example 7-2 except that the oxide-containing film was not provided.

  For the fabricated secondary batteries of Examples 7-1 to 7-5 and Comparative example 7-1, cycle characteristics were examined in the same manner as in Examples 6-1 to 6-11. The results are shown in Table 7 together with Example 6-1 and Comparative example 6-1.

As shown in Table 7, from comparison between Example 6-1 and Examples 7-1 to 7-5, in addition to LiPF ₆ , LiBF ₄ , a compound of Chemical formula 8 (6), Chemical formula 9 It was found that higher cycle characteristics can be obtained by including the compound (2), the compound (13), and the like. In addition, comparison between Example 7-2 and Comparative Example 7-1 confirms that the effect of improving the cycle characteristics by providing a film can be obtained even when another electrolyte salt is added to LiPF _6. did it.

  Although the present invention has been described with reference to the embodiments and examples, the present invention is not limited to the embodiments and examples, and various modifications can be made. For example, in the above-described embodiments and examples, the case where the electrolyte solution or the gel electrolyte in which the polymer solution is held in the polymer compound is used as the electrolyte has been described, but other electrolytes may be used. Other electrolytes include, for example, ion conductive inorganic compounds such as ion conductive ceramics, ion conductive glass or ionic crystals, or other inorganic compounds, or a mixture of these inorganic compounds and an electrolyte or gel electrolyte. The thing which was done is mentioned.

  In the above embodiment and examples, a battery using lithium as an electrode reactant has been described. However, other alkali metals such as sodium (Na) or potassium (K), magnesium (Mg), or calcium (Ca). The present invention can also be applied to the case of using alkaline earth metals such as other light metals or other light metals such as aluminum.

  Further, in the above-described embodiment or example, a cylindrical type, laminated film type, or coin type secondary battery has been specifically described, but the present invention has other shapes such as a button type or a square type. The present invention can be similarly applied to a secondary battery or a secondary battery having another structure such as a laminated structure. Further, the present invention is not limited to the secondary battery, and can be similarly applied to other batteries such as a primary battery.

  Moreover, although the said Example demonstrated the case where cyclic carbonate was used as a solvent, the same tendency was confirmed also when the chain carbonate which has the halogen represented by Chemical formula 1 is used.

It is sectional drawing showing the structure of the 1st secondary battery which concerns on the 1st Embodiment of this invention. It is sectional drawing which expands and represents a part of winding electrode body in the secondary battery shown in FIG. It is a disassembled perspective view showing the structure of the 2nd secondary battery which concerns on the 1st Embodiment of this invention. It is sectional drawing showing the structure along the IV-IV line of the wound electrode body shown in FIG. It is sectional drawing showing the structure of the secondary battery produced in the Example. 1 shows an example of a peak obtained by X-ray photoelectron spectroscopy relating to a SnCoC-containing material produced in an example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Battery can, 12, 13 ... Insulation board, 14 ... Battery cover, 15 ... Safety valve mechanism, 15A ... Disc board, 16 ... Heat sensitive resistance element, 17, 56 ... Gasket, 20, 30 ... Winding electrode body, 21 , 33, 51 ... positive electrode, 21A, 33A, 51A ... positive electrode current collector, 21B, 33B, 51B ... positive electrode active material layer, 22, 34, 52 ... negative electrode, 22A, 34A, 52A ... negative electrode current collector, 22B, 34B, 52B ... negative electrode active material layer, 23, 35, 53 ... separator, 24 ... center pin, 25, 31 ... positive electrode lead, 26, 32 ... negative electrode lead, 36 ... electrolyte layer, 37 ... protective tape, 40 ... exterior member 41 ... Adhesion film, 54 ... Exterior can, 55 ... Exterior cup.

Claims (26)

A negative electrode current collector, and a negative electrode active material layer provided on the negative electrode current collector,
The negative electrode active material layer contains a negative electrode active material containing at least one of silicon (Si) and tin (Sn) as a constituent element,
The negative electrode active material has a coating film containing at least one oxide selected from the group consisting of silicon, germanium (Ge), and tin and a halide on at least a part of the surface of the negative electrode active material.   The negative electrode according to claim 1, wherein the halide contains a fluoride.   The negative electrode according to claim 1, wherein the coating is formed by a liquid phase deposition method or a sol-gel method.   The coating film is formed by a sol-gel method using a fluorine anion or a compound of fluorine and one of elements in groups 13 to 15 as a sol-gel reaction promoting substance. The negative electrode described.   2. The negative electrode according to claim 1, wherein the coating is formed by a sol-gel method using tetrafluoroborate ions, hexafluorophosphate ions or fluorine ions as a sol-gel reaction promoting substance. The negative electrode according to claim 1, wherein the coating film includes a fluorine anion or a compound of fluorine and one of group 13 to group 15 elements.   The negative electrode according to claim 1, wherein the negative electrode active material layer includes a metal having a metal element that does not alloy with the electrode reactant in a gap between adjacent negative electrode active material particles.   The negative electrode according to claim 7, wherein the metal is filled in a gap between the negative electrode active material particles.   8. The metal element according to claim 7, wherein the metal element is at least one selected from the group consisting of iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), and copper (Cu). Negative electrode. A battery comprising an electrolyte together with a positive electrode and a negative electrode,
The negative electrode has a negative electrode current collector and a negative electrode active material layer provided on the negative electrode current collector,
The negative electrode active material layer contains a negative electrode active material containing at least one of silicon (Si) and tin (Sn) as a constituent element,
The negative electrode active material has a coating film containing at least one oxide of a group consisting of silicon, germanium (Ge), and tin and a halide on at least a part of a surface of the negative electrode active material.   The battery according to claim 10, wherein the halide includes a fluoride.   The battery according to claim 10, wherein the coating is formed by a liquid phase deposition method or a sol-gel method.   11. The coating film is formed by a sol-gel method using a fluorine anion or a compound of fluorine and one of elements in groups 13 to 15 as a sol-gel reaction promoting substance. The battery described.   11. The battery according to claim 10, wherein the coating is formed by a sol-gel method using tetrafluoroborate ions, hexafluorophosphate ions or fluorine ions as a sol-gel reaction promoting substance. The battery according to claim 10, wherein the coating film includes a fluorine anion or a compound of fluorine and one of elements in groups 13 to 15.   The battery according to claim 10, wherein the negative electrode active material layer includes a metal including a metal element that does not alloy with the electrode reactant in a gap between the adjacent negative electrode active material particles.   The battery according to claim 16, wherein the metal is filled in a gap between the negative electrode active material particles.   The metal element is at least one selected from the group consisting of iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), and copper (Cu). battery. The electrolyte includes at least one selected from the group consisting of a chain carbonate having a halogen represented by Chemical Formula 1 and a cyclic carbonate having a halogen represented by Chemical Formula 2 as a solvent. Item 11. The battery according to Item 10.

(R11 to R16 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, which may be the same or different from each other, but at least one of them is a halogen group or a halogenated alkyl group. is there.)

(R21 to R24 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and they may be the same or different, but at least one of them is a halogen group or a halogenated alkyl group. is there.) The chain carbonate having halogen includes at least one of fluoromethyl methyl carbonate, bis (fluoromethyl) carbonate and difluoromethyl methyl carbonate,
The cyclic ester carbonate having halogen includes at least one of 4-fluoro-1,3-dioxolan-2-one and 4,5-difluoro-1,3-dioxolan-2-one. The battery according to claim 19.   The battery according to claim 10, wherein the electrolyte contains sultone as a solvent.   The battery according to claim 10, wherein the electrolyte contains an acid anhydride as a solvent. 11. The battery according to claim 10, wherein the electrolyte contains at least one selected from the group consisting of compounds represented by Chemical Formula 3, Chemical Formula 4 and Chemical Formula 5 as an electrolyte salt.

(X31 is a 1A group element or 2A group element or aluminum (Al) in the short period type periodic table. M31 is a transition metal, or a 3B group element, 4B group element or 5B group element in the short period type periodic table. R31 is a halogen group, Y31 is —OC—R32—CO—, —OC—CR33 ₂ — or —OC—CO—, wherein R32 is an alkylene group, a halogenated alkylene group, an arylene group or a halogenated group. R33 is an alkyl group, a halogenated alkyl group, an aryl group or a halogenated aryl group, which may be the same or different from each other, wherein a3 is an integer of 1 to 4, and b3 is (It is an integer of 0, 2 or 4. c3, d3, m3 and n3 are integers of 1 to 3.)

(X41 is a Group 1A element or a Group 2A element in the short period type periodic table. M41 is a transition metal, or a Group 3B element, a Group 4B element, or a Group 5B element in the short period type periodic table. Y41 is —OC—. _{(CR41 2) b4 -CO -,} - R43 2 C- (CR42 2) c4 -CO -, - R43 2 C- (CR42 2) c4 -CR43 2 -, - R43 2 C- (CR42 2) c4 -SO ₂ —, —O ₂ S— (CR42 ₂ ) _d4 —SO ₂ — or —OC— (CR42 ₂ ) _d4 —SO ₂ —, wherein R41 and R43 are hydrogen, alkyl, halogen or halogenated Each of which may be the same as or different from each other, at least one of which is a halogen group or a halogenated alkyl group, R42 is a hydrogen group, an alkyl group A halogen group or a halogenated alkyl group, which may be the same or different from each other, wherein a4, e4 and n4 are integers of 1 or 2, b4 and d4 are integers of 1 to 4, c4 is an integer of 0 to 4, and f4 and m4 are integers of 1 to 3.)

(X51 is a group 1A element or a group 2A element in the short period type periodic table. M51 is a transition metal, or a group 3B element, a group 4B element or a group 5B element in the short period type periodic table. Rf is the number of carbon atoms = A fluorinated alkyl group having 1 to 10 carbon atoms or a fluorinated aryl group having 1 to 10 carbon atoms, Y51 is —OC— (CR51 ₂ ) _d5 —CO—, —R52 ₂ C— (CR51 ₂ ) _d5 —CO—. _{, -R52 2 C- (CR51 2)} d5 -CR52 2 -, - R52 2 C- (CR51 2) d5 -SO 2 -, - O 2 S- (CR51 2) e5 -SO 2 - or -OC- ( CR51 _{2) e5} -SO ₂ -. is, however, R51 is a hydrogen group, an alkyl group, a halogen group or a halogenated alkyl group, it is .R52 may differ and may be identical to one another hydrogen group, an alkyl group A halogen group or a halogenated alkyl group, which may be the same as or different from each other, at least one of which is a halogen group or a halogenated alkyl group, wherein a5, f5 and n5 are 1 or 2; B5, c5 and e5 are integers of 1 to 4, d5 is an integer of 0 to 4, and g5 and m5 are integers of 1 to 3.) The compound represented by Chemical Formula 3 includes at least one of the compounds represented by Chemical Formula 6 (1) to Chemical Formula 6 (6),
The compound represented by Chemical Formula 4 includes at least one of the compounds represented by Chemical Formula 7 (1) to Chemical Formula 7 (8),
24. The battery according to claim 23, wherein the compound represented by chemical formula 5 is a compound represented by chemical formula 7 (9).
The electrolyte comprises, as an electrolyte salt, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, and compounds represented by chemical formula 8, chemical formula 9 and chemical formula 10. The battery according to claim 10, comprising at least one member of the group.

(M and n are integers of 1 or more, and they may be the same or different.)

(R61 is a linear or branched perfluoroalkylene group having 2 to 4 carbon atoms.)

(P, q and r are integers of 1 or more, and they may be the same or different from each other.) The battery according to claim 10, wherein the coating is also provided on a surface of the negative electrode active material in a region other than a region of the negative electrode active material layer facing the positive electrode active material layer of the positive electrode. .