JP2007103197A - Negative electrode, and battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a negative electrode capable of improving cycle characteristics, and a battery using the same. <P>SOLUTION: A negative electrode active material layer 12 containing Si is provided on a negative electrode collector 11. The negative electrode collector 11 is roughened by providing a base material projection part 11B on a base material 11A, and a surface projection part 11C smaller than the base material projection part 11B is formed on a surface of the base material projection part 11B. Thereby, adhesiveness of the negative electrode collector 11 and the negative electrode active material layer 12 is improved, and exfoliation of the negative electrode active material layer 12 is suppressed even when the negative electrode active material layer 12 is expanded or contracted by discharge and charge. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a negative electrode in which a negative electrode active material layer containing silicon (Si) as a constituent element is provided on a negative electrode current collector, and a battery including the same.

  In recent years, as mobile devices have higher performance and more functions, there is a demand for higher capacities of secondary batteries serving as power sources thereof. Secondary batteries that meet this requirement include lithium ion secondary batteries, but those currently in practical use use graphite for the negative electrode, so the battery capacity is saturated and it is difficult to achieve significant increases in capacity. . Therefore, it has been studied to use silicon or the like for the negative electrode, and recently, it has been reported that a negative electrode active material layer is formed on the negative electrode current collector by a vapor phase method or the like. Since silicon and the like have a large expansion / contraction due to charging / discharging, deterioration of cycle characteristics due to pulverization has been a problem. However, according to a vapor phase method or the like, miniaturization can be suppressed and a negative electrode current collector and Since the negative electrode active material layer can be integrated, the electron conductivity in the negative electrode becomes extremely good, and high performance is expected in terms of capacity and cycle life.

However, even in the negative electrode in which the negative electrode current collector and the negative electrode active material layer are integrated as described above, when the charge and discharge are repeated, the negative electrode current collector and the negative electrode active material layer are separated by vigorous expansion and contraction of the negative electrode active material layer. There was a problem in that stress was applied in the meantime, the negative electrode active material layer was dropped, and the cycle characteristics deteriorated. Then, improving the adhesiveness with a negative electrode collector by roughening a negative electrode collector is examined (for example, refer patent documents 1, 2).
International Publication No. WO01 / 031723 Pamphlet JP 2002-313319 A

  However, even with these techniques, peeling of the negative electrode active material layer is inevitable, and there is a problem that it is difficult to sufficiently improve cycle characteristics.

  The present invention has been made in view of such problems, and an object thereof is to provide a negative electrode and a battery that can improve adhesion between the negative electrode current collector and the negative electrode active material layer and suppress peeling of the negative electrode active material layer. There is to do.

  A negative electrode according to the present invention includes a negative electrode current collector provided with a negative electrode active material layer containing silicon as a constituent element. The negative electrode current collector includes a base material and a base material protrusion provided on the base material. The surface protrusion part smaller than this base material protrusion part is formed in the surface in at least one part of this base material protrusion part.

  A battery according to the present invention includes an electrolyte together with a positive electrode and a negative electrode. The negative electrode includes a negative electrode current collector provided with a negative electrode active material layer containing silicon as a constituent element. Material and a base projection provided on the base, and a surface projection smaller than the base projection is formed on the surface of at least a part of the base projection. Is.

  According to the negative electrode of the present invention, since the surface protrusion is provided on the surface of the base material protrusion, the adhesion between the negative electrode current collector and the negative electrode active material layer can be improved. Peeling can be suppressed. Therefore, according to the battery of the present invention, battery characteristics such as cycle characteristics can be improved.

  In particular, if the average diameter of the base protrusion is 50 nm or more and 5 μm or less, a higher effect can be obtained.

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

  FIG. 1 shows a configuration of a negative electrode 10 according to an embodiment of the present invention. The negative electrode 10 has, for example, a structure in which a negative electrode current collector 11 is provided with a negative electrode active material layer 12 containing silicon as a constituent element. This is because silicon has a large ability to occlude and release lithium (Li), and a high energy density can be obtained. Silicon may be contained as a simple substance, an alloy, a compound, or a mixture of two or more thereof. Although FIG. 1 shows the case where the negative electrode active material layer 12 is provided on one surface of the negative electrode current collector 11, the negative electrode active material layer 12 may be provided on both surfaces of the negative electrode current collector 11.

  The negative electrode current collector 11 has a base material 11A and a particulate base material protrusion 11B provided on the base material 11A. This is because the adhesion between the negative electrode current collector 11 and the negative electrode active material layer 12 can be improved by the anchor effect of the base material protruding portion 11B.

  The base material 11A is preferably made of a metal material containing a metal element that does not form an intermetallic compound with lithium. This is because when lithium and an intermetallic compound are formed, they expand and contract with charge / discharge, structural breakdown occurs, current collection performance decreases, and the ability to support the negative electrode active material layer 12 decreases. Note that in this specification, the metal material includes not only a single metal element but also an alloy composed of two or more metal elements or one or more metal elements and one or more metalloid elements. Examples of the metal element that does not form an intermetallic compound with lithium include copper (Cu), nickel (Ni), titanium (Ti), iron (Fe), and chromium (Cr).

  Further, it may be more preferable that the base material 11 </ b> A contains a metal element that can be alloyed with the negative electrode active material layer 12. This is because the adhesion between the negative electrode current collector 11 and the negative electrode active material layer 12 can be further improved by alloying. Examples of the metal element that forms an alloy with lithium and does not form an intermetallic compound with lithium, that is, the metal element that forms an alloy with silicon, include copper, nickel, and iron. Among these, copper is preferable from the viewpoints of conductivity and strength.

  The base material 11A may be composed of a single layer, but may be composed of a plurality of layers. In that case, the layer in contact with the negative electrode active material layer 12 may be made of a metal material that is easily alloyed with the negative electrode active material layer 12, and the other layers may be made of another metal material.

  The base protrusion 11B only needs to be provided at least on the surface of the base 11A on which the negative electrode active material layer 12 is formed, and preferably includes an element that can be alloyed with the negative electrode active material layer 12. This is because the adhesion with the negative electrode active material layer 12 can be further improved by alloying. Examples of elements that are easily alloyed with silicon include copper, nickel, iron, aluminum (Al), indium (In), cobalt (Co), manganese (Mn), zinc (Zn), silver (Ag), and tin (Sn). ), Germanium (Ge) or lead (Pb). The constituent elements of the base protrusion 11B may be the same as or different from those of the base 11A.

  The base protrusion 11B may have any shape such as a spherical shape or a square shape. The average diameter of the base protrusion 11B is preferably 50 nm to 5 μm, and more preferably 100 nm to 4 μm. This is because if the average diameter is too small, a sufficient anchoring effect cannot be obtained, and if it is too large, the adhesion between the negative electrode current collector 11 and the negative electrode active material layer 12 tends to decrease.

  A surface projection 11C having a size smaller than that of the substrate projection 11B is formed on the surface of at least a part of the substrate projection 11B. This is because the adhesion between the negative electrode current collector 11 and the negative electrode active material layer 12 can be further improved by the surface protrusion 11C. The surface protrusion 11C preferably contains an element that can be alloyed with the negative electrode active material layer 12, similarly to the base protrusion 11B. The constituent elements of the surface protrusion 11C may be the same as or different from the base protrusion 11B, and may be the same as or different from the base 11A. Moreover, it is preferable that the surface protrusion part 11C is formed radially from the surface of the base material protrusion part 11B. This is because a higher effect can be obtained.

  The negative electrode active material layer 12 is preferably formed at least partly by, for example, one or more methods selected from the group consisting of a vapor phase method, a liquid phase method, a firing method, and a thermal spray method. It may be formed by combining two or more. Breakage due to expansion / contraction of the negative electrode active material layer 12 due to charge / discharge can be suppressed, the negative electrode current collector 11 and the negative electrode active material layer 12 can be integrated, and electrons in the negative electrode active material layer 12 can be integrated. This is because the conductivity can be improved. Note that the “firing method” means that a layer formed by mixing a powder containing an active material and a binder is heat-treated in a non-oxidizing atmosphere or the like, so that the volume density is higher than that before the heat treatment and the denser. It means the method of forming a layer.

  The negative electrode active material layer 12 is preferably alloyed with the negative electrode current collector 11 at least at a part of the interface with the negative electrode current collector 11. Specifically, the constituent elements of the negative electrode current collector 11 are diffused in the negative electrode active material layer 12, the constituent elements of the negative electrode active material layer 12 are diffused in the negative electrode current collector 11, or they are mutually diffused at the interface. preferable. This is because the adhesion can be improved and the negative electrode active material layer 12B can be prevented from falling off the negative electrode current collector 12A due to expansion and contraction. Note that in this specification, the above-described element diffusion is also included in one form of alloying.

  The negative electrode 10 can be manufactured as follows, for example.

  First, a metal foil is prepared as the base 11A, and the base protrusion 11B and the surface protrusion 11C are formed on the metal foil by an electrolytic deposition method or the like, so that the negative electrode current collector 11 is manufactured. At that time, it is preferable to use an electrolytic copper foil for the base material 11A because the negative electrode current collector 11 can be easily manufactured.

  Next, the negative electrode 12 is produced by forming the negative electrode active material layer 12B on the negative electrode current collector 11 by using, for example, a vapor phase method, a liquid phase method, a firing method, a thermal spraying method, or two or more methods thereof. . Examples of the vapor phase method include a physical deposition method or a chemical deposition method. Specifically, a vacuum deposition method, a sputtering method, an ion plating method, a laser ablation method, or a CVD (Chemical Vapor Deposition; chemical vapor phase). (Growth) method. Examples of the liquid phase method include plating.

  Note that although the negative electrode active material layer 12 and the negative electrode current collector 11 may be alloyed at the same time when the negative electrode active material layer 12 is formed, the negative electrode active material layer 12 is formed in a vacuum atmosphere after forming the negative electrode active material layer 12. Alternatively, heat treatment may be performed in a non-oxidizing atmosphere to form an alloy. Thereby, the negative electrode 10 shown in FIG. 1 is obtained.

  This negative electrode 10 is used for the following secondary batteries, for example.

  FIG. 2 shows the configuration of the secondary battery. This secondary battery is a so-called coin-type battery, in which the negative electrode 10 accommodated in the exterior cup 21 and the positive electrode 23 accommodated in the exterior can 22 are stacked via a separator 24. is there. In FIG. 2, depiction of the base protrusion 11B and the surface protrusion 11C is omitted.

  The peripheral portions of the outer cup 21 and the outer can 22 are sealed by caulking through an insulating gasket 25. The exterior cup 21 and the exterior can 22 are made of, for example, a metal such as stainless steel or aluminum.

  The positive electrode 23 includes, for example, a positive electrode current collector 23A and a positive electrode active material layer 23B provided on the positive electrode current collector 23A so that the positive electrode active material layer 23B side faces the negative electrode active material layer 12. Is arranged. The positive electrode current collector 23A is made of, for example, aluminum, nickel, stainless steel, or the like.

The positive electrode active material layer 23B includes, for example, any 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 the like as necessary. A binder such as polyvinylidene fluoride may be included. As the positive electrode material capable of inserting and extracting lithium, for example, a lithium-containing metal composite oxide represented by the general formula Li _x MIO ₂ is preferable. This is because the lithium-containing metal composite oxide can generate a high voltage and has a high density, so that the capacity of the secondary battery can be further increased. MI is one or more kinds of transition metals, and for example, at least one of cobalt and nickel is preferable. x varies depending on the charge / discharge state of the battery and is usually a value in the range of 0.05 ≦ x ≦ 1.10. Specific examples of such a lithium-containing metal composite oxide include LiCoO _{2 and} LiNiO ₂ .

  The positive electrode 23 is prepared, for example, by mixing a positive electrode active material, a conductive material, and a binder to prepare a mixture, and dispersing the mixture in a dispersion medium such as N-methyl-2-pyrrolidone. This mixture slurry is applied to the positive electrode current collector 23A made of a metal foil, dried, and then compression molded to form the positive electrode active material layer 23B.

  The separator 24 separates the negative electrode 10 and the positive electrode 23 and allows lithium ions to pass through while preventing a short circuit of current due to contact between both electrodes. The separator 24 is made of, for example, polyethylene or polypropylene.

  The separator 24 is impregnated with an electrolytic solution that is a liquid electrolyte. This electrolytic solution contains, for example, a solvent and an electrolyte salt dissolved in this solvent, and may contain an additive as necessary. Examples of the solvent include nonaqueous solvents such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. Any one of the solvents may be used alone, or two or more of them may be mixed and used.

Examples of the electrolyte salt include lithium salts such as LiPF ₆ , LiCF ₃ SO _{3, and} LiClO ₄ . Any one electrolyte salt may be used alone, or two or more electrolyte salts may be mixed and used.

  This secondary battery can be manufactured, for example, by laminating the negative electrode 10, the separator 24 impregnated with the electrolytic solution, and the positive electrode 23, placing them in the outer cup 21 and the outer can 22, and caulking them. it can.

  In the secondary battery, when charged, for example, lithium ions are extracted from the positive electrode 23 and inserted in the negative electrode 10 through the electrolytic solution. When discharging is performed, for example, lithium ions are released from the negative electrode 10 and inserted in the positive electrode 23 via the electrolytic solution. In this embodiment, since the negative electrode current collector 11 provided with the surface protrusion 11C on the base material protrusion 11B is used, the adhesion between the negative electrode current collector 11 and the negative electrode active material layer 12 is improved. Even if the negative electrode active material layer 12 expands and contracts due to charge and discharge, peeling of the negative electrode active material layer 12 is suppressed.

  The negative electrode 10 according to the present embodiment may be used for the following secondary battery.

  FIG. 3 shows the configuration of the secondary battery. In this secondary battery, the wound electrode body 30 to which the leads 31 and 32 are attached is housed in a film-like exterior member 41, and can be reduced in size, weight, and thickness.

  The leads 31 and 32 are led out from the inside of the exterior member 41 to the outside, for example, in the same direction. The leads 31 and 32 are made of a metal material such as aluminum, copper, nickel, or stainless steel, respectively, and have a thin plate shape or a mesh shape, respectively.

  The exterior member 41 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. The exterior member 41 is disposed, for example, so that the polyethylene film side and the electrode winding body 30 face each other, and the outer edge portions are in close contact with each other by fusion or an adhesive. An adhesion film 42 for preventing the entry of outside air is inserted between the exterior member 41 and the leads 31 and 32. The adhesion film 42 is made of a material having adhesion to the leads 31 and 32, for example, a polyolefin resin such as polyethylene, polypropylene, modified polyethylene, or modified polypropylene.

  The exterior member 41 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 II of the electrode winding body 30 shown in FIG. The electrode winding body 30 is obtained by laminating and winding the negative electrode 10 and the positive electrode 33 with the separator 34 and the electrolyte layer 35 interposed therebetween, and the outermost peripheral portion is protected by a protective tape 36. In addition, in FIG. 4, illustration of the base material projection part 11B and the surface projection part 11C is abbreviate | omitted.

  The negative electrode 10 has a structure in which a negative electrode active material layer 12 is provided on both surfaces of a negative electrode current collector 11. The positive electrode 33 also has a structure in which the positive electrode active material layer 33B is provided on both surfaces of the positive electrode current collector 33A, and the positive electrode active material layer 33B and the negative electrode active material layer 12 are arranged to face each other. The configurations of the positive electrode current collector 33A, the positive electrode active material layer 33B, and the separator 34 are the same as those of the positive electrode current collector 23A, the positive electrode active material layer 23B, and the separator 24 described above.

  The electrolyte layer 35 is configured by a so-called gel electrolyte in which an electrolytic solution is held in a holding body made of a polymer compound. 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 coin-type secondary battery shown in FIG. An example of the polymer material is polyvinylidene fluoride.

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

  First, on each of the negative electrode 10 and the positive electrode 33, an electrolyte layer 35 in which an electrolytic solution is held in a holding body is formed, and leads 31 and 32 are attached. Next, the negative electrode 10 on which the electrolyte layer 35 is formed and the positive electrode 33 are laminated via the separator 34 and wound, and the protective tape 36 is adhered to the outermost peripheral portion to form the electrode winding body 30. Subsequently, for example, the electrode winding body 30 is sandwiched between the exterior members 41, and the outer edge portions of the exterior members 41 are sealed and sealed by thermal fusion or the like. At that time, the adhesion film 42 is inserted between the leads 31 and 32 and the exterior member 41. Thereby, the secondary battery shown in FIGS. 3 and 4 is completed.

  Moreover, you may manufacture as follows. First, after the leads 31 and 32 are attached to the negative electrode 10 and the positive electrode 33, the negative electrode 10 and the positive electrode 33 are laminated and wound via the separator 34, and the protective tape 36 is adhered to the outermost peripheral portion to A wound body that is a precursor of the wound body 30 is formed. Next, the wound body is sandwiched between exterior members 41, and the outer peripheral edge except for one side is heat-sealed into a bag shape, and then the electrolyte, the monomer that is the raw material of the polymer compound, the polymerization initiator, An electrolyte composition containing another material such as a polymerization inhibitor is injected into the exterior member 41 as necessary. Subsequently, the opening of the exterior member 41 is heat-sealed and sealed in a vacuum atmosphere, and heat is applied to polymerize the monomer to form a polymer compound, thereby forming the gel electrolyte layer 35. Thereby, the secondary battery shown in FIGS. 3 and 4 is completed.

  The operation of this secondary battery is the same as that of the coin-type secondary battery shown in FIG.

  As described above, according to the present embodiment, since the surface protrusion 11C is provided on the surface of the base material protrusion 11B, the adhesion between the negative electrode current collector 11 and the negative electrode active material layer 12 can be improved. And the peeling of the negative electrode active material layer 12 can be suppressed. Therefore, battery characteristics such as cycle characteristics can be improved.

  In particular, if the average diameter of the base protrusion 11B is set to 50 nm or more and 5 μm or less, a higher effect can be obtained.

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

(Examples 1-1 to 1-7)
A secondary battery having the structure shown in FIGS.

  First, an electrolytic copper foil having a thickness of 12 μm was prepared as the base material 11A, and the negative electrode current collector 11 was prepared by forming the base protrusion 11B and the surface protrusion 11C by electrolytic deposition. At that time, the average diameter of the base protrusion 11B was changed as shown in Table 1 in Examples 1-1 to 1-7. When the surface state of each of the manufactured negative electrode current collectors 11 was observed with a scanning electron microscope (SEM), it was confirmed that the surface protrusions 11C were radially formed on the surface of the base protrusion 11B. It was done. 5 and 6 representatively show SEM photographs of Example 1-3. FIG. 6 is an enlarged view of a part of FIG. Next, a negative electrode active material layer 12 made of silicon and having a thickness of about 9 μm was formed on the negative electrode current collector 11 by vacuum deposition, and heat treatment was performed in a reduced-pressure atmosphere. A cross section of the prepared negative electrode 10 was cut out, and the interface between the negative electrode current collector 11 and the negative electrode active material layer 12 was analyzed by AES (Auger electron spectroscopy). It was confirmed that the copper component of the electric body 11 was diffused. That is, it was confirmed that the negative electrode current collector 11 and the negative electrode active material layer 12 were alloyed.

Also, 92 parts by mass of lithium cobaltate (LiCoO ₂ ) powder having an average particle diameter of 5 μm as a positive electrode active material, 3 parts by mass of carbon black as a conductive material, and 5 parts by mass of polyvinylidene fluoride as a binder are mixed. This was put into N-methyl-2-pyrrolidone as a dispersion medium to form a slurry. Next, this was applied to a positive electrode current collector 33A made of an aluminum foil having a thickness of 15 μm, dried, and then pressed to form a positive electrode active material layer 33B.

Subsequently, 37.5% by mass of ethylene carbonate, 37.5% by mass of propylene carbonate, 10% by mass of vinylene carbonate, and 15% by mass of LiPF ₆ were prepared to prepare an electrolyte solution, and 30 parts by mass of this electrolyte solution Then, 10 parts by mass of polyvinylidene fluoride, which is a block copolymer having a weight average molecular weight of 600,000, were mixed and applied to both surfaces of the negative electrode 10 and the positive electrode 33 to form the electrolyte layer 35.

  After that, the leads 31 and 32 were attached, the negative electrode 10 and the positive electrode 33 were laminated via a separator 34 and wound, and sealed in an exterior member 41 made of an aluminum laminate film. Thus, secondary batteries of Examples 1-1 to 1-7 were obtained.

  As Comparative Examples 1-1 to 1-3 with respect to Examples 1-1 to 1-7, except that no surface protrusion was formed on the negative electrode current collector, Example 1-1 to 1-7 were otherwise used. Similarly, a secondary battery was produced. At that time, the average diameter of the base protrusions was changed as shown in Table 1 in Comparative Examples 1-1 to 1-3. When the surface state of the negative electrode current collectors of Comparative Examples 1-1 to 1-3 was observed by SEM, it was confirmed that only the base material protrusions were formed. 7 and 8 representatively show SEM photographs of Comparative Example 1-2. FIG. 8 is an enlarged view of a part of FIG.

The fabricated secondary batteries of Examples 1-1 to 1-7 and Comparative Examples 1-1 to 1-3 were subjected to a charge / discharge test under the condition of 25 ° C., and the discharge capacity was maintained at the 31st cycle relative to the 2nd cycle. The rate was determined. At that time, charging is performed at a constant current density of 1 mA / cm ² until the battery voltage reaches 4.2 V, and then at a constant voltage of 4.2 V until the current density reaches 0.05 mA / cm ^2. Was performed at a constant current density of 1 mA / cm ² until the battery voltage reached 2.5V. In addition, when performing charging, the utilization factor of the capacity of the negative electrode 10 was set to 90% so that metallic lithium was not deposited on the negative electrode 10. The discharge capacity retention ratio was calculated as the ratio of the discharge capacity at the 31st cycle to the discharge capacity at the 2nd cycle, that is, (discharge capacity at the 31st cycle / discharge capacity at the 2nd cycle) × 100. The results are shown in Table 1.

  As shown in Table 1, according to Examples 1-1 to 1-7, the discharge capacity retention ratio could be improved as compared with Comparative Examples 1-1 to 1-3. That is, if the surface protrusion 11C is provided on the surface of the base protrusion 11B, the adhesion between the negative electrode current collector 11 and the negative electrode active material layer 12 can be improved, and battery characteristics such as cycle characteristics can be improved. It has been found that it can be improved.

(Examples 2-1 and 2-2)
A secondary battery was fabricated in the same manner as in Examples 1-1 and 1-3 except that the negative electrode active material layer 12 was formed by a firing method. The negative electrode active material layer 12 was applied to the negative electrode current collector 11 by dispersing 90 parts by mass of silicon powder having an average particle diameter of 1 μm and 1 part by mass of polyvinylidene fluoride in N-methyl-2-pyrrolidone as a dispersion medium. After drying and pressing, the film was formed by heat treatment at 400 ° C. for 12 hours in a vacuum atmosphere. The negative electrode current collector 11 used in Example 2-1 is the same as that in Example 1-1, and the negative electrode current collector 11 used in Example 2-2 is the same as that in Example 1-3.

  Moreover, as Comparative Example 2-1 with respect to Examples 2-1 and 2-2, except that the same negative electrode current collector as that of Comparative Example 1-2 was used, the rest was the same as in Examples 2-1 and 2-2. Similarly, a secondary battery was produced. For the secondary batteries of Examples 2-1 and 2-2 and Comparative Example 2-1, the discharge capacity retention ratio was determined 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 result was obtained when the negative electrode active material layer 12 was formed by a firing method.

  Although the present invention has been described with reference to the embodiments and examples, the present invention is not limited to the above embodiments and examples, and various modifications can be made. For example, in the above-described embodiments and examples, the case where an electrolytic solution which is a liquid electrolyte or a so-called gel electrolyte is used has been described, but another electrolyte may be used. Examples of other electrolytes include solid electrolytes having ionic conductivity, a mixture of a solid electrolyte and an electrolyte solution, and a mixture of a solid electrolyte and a gel electrolyte.

  As the solid electrolyte, for example, a polymer solid electrolyte in which an electrolyte salt is dispersed in a polymer compound having ion conductivity, or an inorganic solid electrolyte made of ion conductive glass or ionic crystals can be used. Examples of the polymer compound of the solid polymer electrolyte 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, and an acrylate polymer compound. Or can be copolymerized. As the inorganic solid electrolyte, one containing lithium nitride or lithium phosphate can be used.

  In the above embodiments and examples, a coin type or wound laminate type secondary battery has been described. However, the present invention is not limited to a cylindrical type, a square type, a button type, a thin type, a large size, or a laminated laminate type. The present invention can be similarly applied to a secondary battery having the shape. In addition, the present invention can be applied not only to secondary batteries but also to primary batteries.

It is sectional drawing showing the structure of the negative electrode which concerns on one embodiment of this invention. It is sectional drawing showing the structure of the secondary battery using the negative electrode shown in FIG. It is a disassembled perspective view showing the structure of the other secondary battery using the negative electrode shown in FIG. It is sectional drawing showing the structure along the II line of the secondary battery shown in FIG. It is a SEM photograph showing the surface structure of the negative electrode collector which concerns on Example 1-3. 6 is an SEM photograph showing an enlarged part of the negative electrode current collector shown in FIG. 5. It is a SEM photograph showing the surface structure of the negative electrode collector which concerns on Comparative Example 1-3. 8 is an SEM photograph showing an enlarged part of the negative electrode current collector shown in FIG. 7.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Negative electrode, 11 ... Negative electrode collector, 11A ... Base material, 11B ... Base material protrusion part, 11C ... Surface protrusion part, 12 ... Negative electrode active material layer, 21 ... Exterior cup, 22 ... Exterior can, 23, 33 ... Positive electrode, 23A, 33A ... Positive electrode current collector, 23B, 33B ... Positive electrode active material layer, 24, 34 ... Separator, 25 ... Gasket, 31, 32 ... Lead, 30 ... Electrode wound body, 35 ... Electrolyte layer, 36 ... Protective tape

Claims (14)

A negative electrode provided with a negative electrode active material layer containing silicon (Si) as a constituent element on a negative electrode current collector,
The negative electrode current collector has a base material, and a base material protrusion provided on the base material,
A negative electrode characterized in that a surface protrusion smaller than the base protrusion is formed on the surface of at least a part of the base protrusion.   2. The negative electrode according to claim 1, wherein the base protrusion has a particle shape and an average diameter of 50 nm to 5 μm.   The negative electrode according to claim 1, wherein the surface protrusion is formed radially from the surface of the base protrusion.   The negative electrode according to claim 1, wherein the base protrusion and the surface protrusion are formed by electrolytic deposition.   The negative electrode according to claim 1, wherein the base material is an electrolytic copper foil.   The negative electrode according to claim 1, wherein the negative electrode current collector and the negative electrode active material layer are alloyed at least at a part of the interface.   2. The negative electrode according to claim 1, wherein at least a part of the negative electrode active material layer is formed by one or more methods selected from the group consisting of a vapor phase method, a liquid phase method, a firing method, and a thermal spray method. . A battery comprising an electrolyte together with a positive electrode and a negative electrode,
The negative electrode is provided with a negative electrode active material layer containing silicon (Si) as a constituent element in a negative electrode current collector,
The negative electrode current collector has a base material, and a base material protrusion provided on the base material,
A battery having a surface protrusion smaller than the base protrusion on the surface of at least a part of the base protrusion.   The battery according to claim 8, wherein the base protrusion is particulate and has an average diameter of 50 nm to 5 μm.   The battery according to claim 8, wherein the surface protrusion is formed radially from the surface of the base protrusion.   9. The battery according to claim 8, wherein the base protrusion and the surface protrusion are formed by electrolytic deposition.   The battery according to claim 8, wherein the base material is an electrolytic copper foil.   The battery according to claim 8, wherein the negative electrode current collector and the negative electrode active material layer are alloyed at least at a part of the interface.   9. The battery according to claim 8, wherein at least a part of the negative electrode active material layer is formed by one or more methods selected from the group consisting of a vapor phase method, a liquid phase method, a firing method, and a thermal spray method. .

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