JP2007220451A - Anode for lithium secondary battery and lithium secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-capacity lithium secondary battery in which a material which can make an alloy with lithium is used as an anode active substance and a peeling off of this material because of swelling at a time of charging can be prevented and deterioration of service life due to a fine internal short circuit together with a work of a surface layer formed on the anode can be controlled. <P>SOLUTION: The anode for a lithium secondary battery is composed of a compound layer, made of active substance particles which can make an alloy with lithium, a carbon material and an adhesive agent, provided on a collector, and the surface layer, made of solid particles, provided on the above compound layer. An average particle diameter of the active substance particle shall be 0.1μm to 10μm, and a first kind having an average particle diameter of 0.1μm to 15μm and a second kind having an average particle diameter of 0.3μ m to 45μ m are used as the carbon materials, and furthermore, an average particle diameter ratio of the first carbon material against the second carbon material shall be 3 to 5 times. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a negative electrode for a lithium secondary battery, and more particularly to a technique for solving the problems of a high-capacity lithium secondary battery.

  With the reduction in size and weight of various electronic devices, demand for lithium secondary batteries with high energy density is increasing. In order to respond to the further increase in capacity from the market, it is essential to improve the negative electrode. As this background, there is a maturation of cell design and electrode manufacturing process for maximizing the theoretical capacity (372 mAh / g) of graphite widely used as a negative electrode active material. That is, in order to further increase the capacity of the negative electrode, it is indispensable to use a material having a theoretical capacity much larger than that of graphite and capable of being alloyed with lithium.

Since materials that can be alloyed with lithium generally have low conductivity, a negative electrode is formed in combination with a carbon material having high conductivity. In addition, this material has significant volume expansion and contraction during charging and discharging. In particular, when this material expands during charging, the distance between the positive electrode and the negative electrode is narrowed, so that a minute internal short circuit is induced and the life characteristics may be deteriorated. Therefore, in addition to a widely used resin separator such as polyethylene, a technique for forming a surface layer capable of transmitting lithium ions on the negative electrode (for example, Patent Documents 1 and 2), hard lithium ion conductive glass ceramics as a solid electrolyte It is considered to be effective to utilize the technique used for the above (for example, Patent Document 3).
Japanese Patent Laid-Open No. 07-220759 Republication 97/001870 Japanese Patent Laid-Open No. 2000-026135

  However, no matter how the techniques of Patent Documents 1 and 2 are utilized, if a negative electrode is randomly formed, peeling occurs due to a volume change of a material that can be alloyed with lithium. I found that I could not prevent it. Although the solid electrolyte of Patent Document 3 has hardness that can suppress the volume change of this material, it is inferior in ionic conductivity as compared with the conventional non-aqueous electrolyte, so that practical discharge characteristics can be realized. I can't.

  The present invention has been made on the basis of the above-mentioned problems. While using a material that can be alloyed with lithium as a negative electrode active material, the material is prevented from peeling off due to expansion during charging, and the surface layer formed on the negative electrode An object of the present invention is to provide a high-capacity lithium secondary battery capable of suppressing a decrease in life characteristics due to a minute internal short circuit in combination with the function.

  In view of the above problems, the negative electrode for a lithium secondary battery according to the present invention is provided with a mixture layer composed of active material particles that can be alloyed with lithium, a carbon material, and a binder on a current collector. A negative electrode for a lithium secondary battery in which a surface layer made of solid particles is provided on a mixture layer, wherein the active material particles have an average particle diameter of 0.1 to 10 μm, and the carbon material has an average particle diameter of 0.1 A first carbon material having a particle diameter of ˜15 μm and a second carbon material having an average particle diameter of 0.3 to 45 μm are used, and the average particle diameter ratio of the second carbon material to the first carbon material is 3 It is characterized by having become 5 times.

As a result of intensive studies, the inventor has made the carbon material contained in the mixture layer not only impart conductivity to the active material particles, but also easily adheres to the binder, so that the adhesion between the mixture layer and the current collector is good. It was clarified that it has the effect of increasing However, unlike the general “relationship between the main agent and additive”, the carbon material has an average particle diameter almost equal to that of the active material particles. A dead space is formed, and the carbon material cannot be efficiently disposed near the surface of the current collector, the adhesiveness is lowered, and the active material particles are easily separated. Therefore, the carbon material having two kinds of average particle diameters is used to reduce dead space, and the carbon material is efficiently arranged near the surface of the current collector, thereby improving the adhesion between the mixture layer and the current collector. Can be increased. Furthermore, the presence of an electrically insulating surface layer can suppress a minute internal short circuit even if a slight peeling occurs in the mixture layer, so that the life characteristics can be improved. By the above effects, a negative electrode for a lithium secondary battery using active material particles that can be alloyed with lithium can be made practical.

  As described above, according to the present invention, it is possible to utilize active material particles that have high capacity but poor conductivity and have many problems associated with volume changes. Therefore, high-capacity lithium secondary batteries that can meet market demands can be widely provided.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  1st invention provides the mixture layer which consists of an active material particle which can be alloyed with lithium, a carbon material, and a binder on a collector, and the surface which consists of solid particles on this mixture layer A lithium secondary battery negative electrode provided with a layer, wherein the average particle diameter of the active material particles is 0.1 to 10 μm, and the average carbon particle diameter is 0.1 to 15 μm as the carbon material and the average The second carbon material having a particle diameter of 0.3 to 45 μm is used, and the average particle diameter ratio of the second carbon material to the first carbon material is 3 to 5 times. To do.

  FIG. 1 is a schematic cross-sectional view showing a negative electrode for a lithium secondary battery of the present invention. A mixture layer 2 is provided on the current collector 1, and a surface layer 3 is provided on the mixture layer 2. In the mixture layer 2, a first carbon material 22, a second carbon material 23 having an average particle diameter larger than this, and a binder 24 are arranged around the active material particles 21 that can be alloyed with lithium. Has been. Although the active material particles 21 are poor in conductivity, the first carbon material 22 and the second carbon material 23 arranged in the periphery can take the active material particles 21 into the conductive network. Furthermore, since the first carbon material 22 is disposed in the dead space composed of the active material particles 21 and the second carbon material 23, the carbon material is uniformly present in the mixture layer 2. This structure not only further strengthens the conductive network described above, but also allows a large amount of carbon material that is easily compatible with the binder 24 to be present on the current collector 1, and as a result, the current collector 1 and the mixture layer 2. Adhesion with is increased. Due to this effect, even if the volume of the active material particles 21 changes during charging and discharging, the active material particles 21 are protected by the three-dimensional structure composed of the carbon material, and thus are difficult to peel off from the negative electrode. Furthermore, since the solid particles 31 in the surface layer 3 have high insulation properties, it is possible to suppress a decrease in life characteristics due to a minute internal short circuit. In addition, since the solid particles 31 have an appropriate hardness, they are not deformed even when the mixture layer 2 presses the surface layer 3 due to the expansion of the active material particles 21 during charging, and the gaps between the solid particles 31 can be maintained appropriately. Therefore, it also has the effect of keeping the ionic conductivity high and improving the life characteristics.

  Examples of the current collector 1 include an electrolytic copper foil and a rolled copper foil. Moreover, it is preferable that the thickness is 8-15 micrometers from a viewpoint of ensuring mechanical strength.

As the active material particles 21, a titanium silicon compound or the like is preferable from the viewpoint of increasing the capacity. The average particle diameter of the active material particles 21 needs to be 0.1 to 10 μm. When the average particle size is less than 0.1 μm, the bulk density is lowered, so that the filling property is lowered, and the mixture layer 2 is remarkably peeled by the load during rolling. On the other hand, if it exceeds 10 μm, the surface area involved in the reaction is reduced, and the battery reaction is inactivated.

  The first carbon material 22 needs to have an average particle diameter of 0.1 to 15 μm, and specifically includes TIMCAL graphite KS4 (trade name). When the average particle size is less than 0.1 μm, the filling property is lowered as a whole, and the mixture layer 2 is remarkably peeled by the load during rolling. On the other hand, if it exceeds 15 μm, the particle size difference from the second carbon material becomes small, the filling property is lowered, and the mixture layer 2 is remarkably peeled by the load during rolling.

  As the 2nd carbon material 23, an average particle diameter needs to be 0.3-45 micrometers, and specifically, Hitachi Chemical graphite MAG (brand name) etc. are mentioned. When the average particle size is less than 0.3 μm, the particle size difference from the first carbon material is reduced, the filling property is lowered, and the mixture layer 2 is remarkably peeled by the load during rolling. On the other hand, when it exceeds 45 μm, the dispersibility in the mixture layer 2 is lowered and the battery reaction is inactivated.

  Here, the average particle diameter ratio of the second carbon material to the first carbon material needs to be 3 to 5 times. When this ratio deviates from the above range, the first carbon material 22 is not well disposed in the dead space formed by the second carbon material 23, so that the filling property is lowered, and the mixture layer 2 is formed by the load during rolling. Remarkably peels off.

  As the binder 24, a fluorine-based material such as PTFE is preferable from the viewpoint of being easily compatible with the first carbon material 22 and the second carbon material 23. The familiarity between the binder 24 and the carbon material is considered to be manifested when the binder component is adsorbed on the carbon material.

  The solid particles 31 constituting the surface layer 3 may be any solid particles that can provide lithium ion conductivity by providing appropriate voids in the surface layer 3. In addition, it is more preferable that the average particle diameter of the solid particles 31 is 0.1 to 3 μm because the gap structure of the surface layer 3 is optimized and the injection property of the electrolytic solution is increased.

  The second invention is characterized in that, in the first invention, at least a part of the surface of the active material particles 21 is coated with a material having higher conductivity than the active material particles 21. An example of such a material is ketjen black. The battery reaction of the active material particles 21 with poor conductivity is activated by the configuration of the second invention.

  The third invention is characterized in that, in the first invention, the surface roughness Ra of the mixture layer 21 is 0.4 to 3 μm. When the mixture layer 21 is smoothed by a process such as rolling, the diffusion of lithium ions is hindered due to the reduction in the reaction area, and therefore an appropriate surface roughness is required. In order to make the surface roughness of the mixture layer 21 0.4 μm or more, there is a method of roughening by sandblasting or the like in addition to using a material having high rigidity and easily maintaining the original particle shape after rolling. It is done. However, if the surface roughness is to be 3 μm or more, it is necessary to perform an excessive sandblast treatment, which is not preferable because a short circuit due to mixing of the scraped mixture layer 21 may occur.

  The fourth invention is characterized in that, in the first invention, the surface layer 3 has a function of holding an electrolytic solution, and the solid particles 31 are water-insoluble. Although the electrolyte solution of the lithium secondary battery uses an organic solvent system, if the water-soluble solid particles 31 are used, the solid particles 31 may not maintain the original shape and may not be able to hold the electrolyte solution.

  The fifth invention is characterized in that, in the fourth invention, an oxide containing at least one of aluminum, silicon, zirconium, and magnesium is used as the solid particles 31. Since these oxides are not only insoluble in water but also have high mechanical strength, it is preferable because the shape of the surface layer 3 can be maintained even when the negative electrode is deformed due to charging / discharging of the battery.

  The sixth invention is characterized in that, in the first invention, the thickness of the surface layer 3 is 1 to 30 μm. If the thickness is less than 1 μm, the volume of the surface layer 3 is excessively small, so that the electrolyte holding power is slightly reduced. If the thickness exceeds 30 μm, the surface layer 3 itself becomes a reaction resistance and the reactivity at the electrode interface is reduced.

  A seventh invention relates to a lithium secondary battery using the first to sixth negative electrodes for lithium secondary batteries.

As the positive electrode, those conventionally used for lithium secondary batteries can be used without limitation. Examples of such positive electrode active materials include lithium-containing transition metal oxides such as LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiMnO ₂ , LiCo _0.5 Ni _0.5 O ₂ , LiNi _0.7 Co _0.2 Mn _0.1 O ₂ , and MnO _2. Examples thereof include metal oxides that do not contain lithium, such as spinel compounds such as titanium spinel compounds such as Li ₄ TiO ₁₂ . In addition, any substance that electrochemically inserts and desorbs lithium can be used without limitation.

The electrolytic solution is not particularly limited, and examples of the solvent include mixed solvents of cyclic carbonates such as ethylene carbonate, propylene carbonate, and butylene carbonate, and chain carbonates such as dimethyl carbonate, methyl ethyl carbonate, and diethyl carbonate. Further, mixed solvents of the cyclic carbonate and ether solvents such as 1,2-dimethoxyethane and 1,2-diethoxyethane are also exemplified. As solutes, LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), Examples include LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ and mixtures thereof. Furthermore, the electrolytic solution is not limited to a liquid phase, and a gel polymer electrolyte obtained by impregnating a polymer electrolyte such as polyethylene oxide or polyacrylonitrile with an electrolytic solution, or ethyl-3-methylimidazolium chloride (EMIC) as a main component. Examples thereof include inorganic solid electrolytes such as molten salt, LiI, and Li ₃ N. The electrolyte of the secondary battery according to the present invention can be used without restriction unless the Li compound as a solvent that develops ionic conductivity and the solvent that dissolves and retains the lithium compound are not decomposed at the potential during charging, discharging, or storage of the battery. be able to.

  Hereinafter, the present invention will be described in more detail based on examples. However, the present invention is not limited to the following examples, and can be implemented with appropriate modifications within a range not changing the gist thereof. Is.

Example 1
The positive electrode was produced as follows. First, Li ₂ CO ₃ and CoCO ₃ are weighed so that the atomic ratio of Li: Co is 1: 1, mixed in a mortar, pressed and pressed, and then in air at 800 ° C. for 24 hours. Firing was performed to obtain a LiCoO ₂ fired body. This was pulverized with a mortar until the average particle size became 20 μm. The resulting LiCoO ₂ powder is 100 parts by weight, acetylene black as a conductive material is 10 parts by weight, and polytetrafluoroethylene as a binder is 10 parts by weight. Got. This mixture was applied to both surfaces of a positive electrode current collector made of an aluminum foil having a thickness of 20 μm, and then dried and rolled to obtain a positive electrode. After the positive electrode lead was spot welded to the positive electrode, vacuum drying was performed at 110 ° C. for 3 hours.

The negative electrode was produced as follows. First, titanium powder having a maximum particle size of 150 μm or less (99.9%) and silicon powder having a maximum particle size of 100 μm or less (99.9%) are mixed at a weight ratio of 1:10, and using a meso-fusion made by Hosokawa Micron. Mechanical alloying treatment was performed at 2000 rpm for 168 hours. As a result of analysis after finely pulverizing the obtained titanium silicon compound, the average particle diameter was 0.3 μm, and a broad peak as proof of amorphization was observed by X-ray diffraction. 4 parts by weight of ketjen black is further added to the active material particles 21 (96 parts by weight), and a mechanical alloying method (at 2000 rpm for 10 minutes) is performed, so that most of the surfaces of the active material particles 21 are made conductive. Coated with high ketjen black. 20 parts by weight of the active material particles 21, 30 parts by weight of graphite (KS4 made by TIMCAL) having an average particle diameter of 4 μm as the first carbon material 22, and graphite having an average particle diameter of 12 μm as the second carbon material 23 ( MAG manufactured by Hitachi Chemical Co., Ltd.), 10 parts by weight of acetylene black as a conductive material, and 10 parts by weight of a solid solution of N-methyl-2-pyrrolidone (NMP) solution of polyvinylidene fluoride as a binder 24 And kneaded to obtain a paste-like negative electrode mixture. This paste was applied to both sides of a negative electrode current collector made of rolled copper foil so as to have a thickness of 100 μm on one side, dried at 60 ° C. for 8 hours, and rolled to form a mixture layer 2. The surface roughness Ra at this time was 0.48 μm. On both surfaces of this mixture layer 2, 970 g of alumina as solid particles 31 and 375 g of polyacrylonitrile modified rubber binder BM-720H (trade name / solid content 8% by weight) manufactured by Nippon Zeon Co., Ltd. as binders. The paste obtained by kneading together with an appropriate amount of NMP was applied and dried to prepare a surface layer 3 having a thickness of 10 μm on one side.

The lithium secondary battery was produced as follows. First, the positive electrode and the negative electrode were wound in an approximately elliptical shape through a 25 μm thick polyethylene separator, and inserted into an aluminum rectangular case having a width of 5.3 mm, a length of 30 mm, and a total height of 48 mm. An electrolyte solution prepared by dissolving 1 mol / liter of LiPF ₆ in an equal volume mixed solvent of ethylene carbonate and diethyl carbonate was poured into this, and sealed to obtain a lithium secondary battery having a theoretical capacity of 950 mAh. This is Example 1.

(Examples 2 to 4)
Compared to Example 1, by changing the finely pulverizing conditions of the titanium silicon compound, the average particle diameter of the active material particles 21 was 0.1 μm (Example 2), 1 μm (Example 3), and 10 μm (Example 3). A lithium secondary battery similar to that of Example 1 was obtained except that. Let this be Examples 2-4.

(Examples 5-6)
In contrast to Example 1, as the second carbon material 23, graphite having an average particle size of 16 μm (Hitachi Chemical MAG / Example 5) and graphite having an average particle size of 20 μm (Hitachi Chemical MAG / Example 6) are used. A lithium secondary battery similar to that of Example 1 was obtained except that there was Let this be Examples 5-6.

(Example 7)
Example 1 is different from Example 1 except that graphite having an average particle diameter of 0.1 μm is used as the first carbon material 22 and graphite having an average particle diameter of 0.3 μm is used as the second carbon material 23. A lithium secondary battery similar to 1 was obtained. This is Example 7.

(Example 8)
In contrast to Example 1, graphite having an average particle diameter of 1 μm was used as the first carbon material 22, and graphite having an average particle diameter of 3 μm was used as the second carbon material 23. A lithium secondary battery was obtained. This is Example 8.

Example 9
In contrast to Example 1, graphite (MAG made by Hitachi Chemical) having an average particle diameter of 10 μm is used as the first carbon material 22, and graphite (MAG made by Hitachi Chemical) having an average particle diameter of 30 μm is used as the second carbon material 23. A lithium secondary battery similar to that of Example 1 was obtained except that it was used. This is shown in Example 9.
And

(Example 10)
For Example 1, graphite having an average particle diameter of 15 μm (MAG made by Hitachi Chemical) is used as the first carbon material 22, and graphite having an average particle diameter of 45 μm (MAG made by Hitachi Chemical) is used as the second carbon material 23. A lithium secondary battery similar to that of Example 1 was obtained except that it was used. This is Example 10.

(Examples 11 to 13)
In contrast to Example 1, the surface roughness Ra of the mixture layer 2 was changed to 0.32 μm (Example 11), 0.4 μm (Example 12), and 1 μm (Example 13) by changing the rolling conditions. Obtained the same lithium secondary battery as Example 1. This is designated as Examples 11 to 13.

(Examples 14 to 15)
Example 1 is performed except that the surface roughness Ra of the mixture layer 2 is set to 3 μm (Example 14) and 3.5 μm (Example 15) by performing sandblasting treatment under different conditions with respect to Example 1. The same lithium secondary battery was obtained. Let this be Examples 14-15.

(Examples 16 to 19)
Example 1 except that the thickness of the surface layer 3 was set to 0.5 μm (Example 16), 1 μm (Example 17), 30 μm (Example 18) and 35 μm (Example 19) with respect to Example 1. The same lithium secondary battery was obtained. Let this be Examples 16-19.

(Examples 20 to 22)
In contrast to Example 3, zirconia (Example 20), silica (Example 21), and magnesia (Example 22) having the same average particle diameter are used as the solid particles 31 of the surface layer 3 instead of alumina. Obtained the same lithium secondary battery as Example 1. Let this be Examples 20-22.

(Comparative Examples 1-2)
Example 1 is different from Example 1 except that the average particle size of the active material particles 21 is set to 0.05 μm (Comparative Example 1) and 12 μm (Comparative Example 2) by changing the finely pulverizing conditions of the titanium silicon compound. A lithium secondary battery similar to 1 was obtained. This is referred to as Comparative Examples 1 and 2.

(Comparative Example 3)
In contrast to Example 1, graphite having an average particle diameter of 0.05 μm was used as the first carbon material 22, and graphite having an average particle diameter of 0.15 μm was used as the second carbon material 23. A lithium secondary battery similar to 1 was obtained. This is referred to as Comparative Example 3.

(Comparative Example 4)
In contrast to Example 1, graphite (MAG made by Hitachi Chemical) having an average particle diameter of 18 μm is used as the first carbon material 22, and graphite (MAG made by Hitachi Chemical) having an average particle diameter of 54 μm is used as the second carbon material 23. A lithium secondary battery similar to that of Example 1 was obtained except that it was used. This is referred to as Comparative Example 4.

(Comparative Examples 5-6)
For Example 1, graphite having an average particle size of 10 μm (MAG / Comparative Example 5) and graphite having an average particle size of 23 μm (MAG / Comparative Example 6 made by Hitachi Chemical) are used as the second carbon material 23. A lithium secondary battery similar to that of Example 1 was obtained except that there was This is designated as Comparative Examples 5-6.

  The obtained lithium secondary battery of each example was charged at a constant voltage and constant current with a charging control voltage of 4.2 V and a maximum current of 950 mA at 20 ° C. until the end of 34 mA. The cycle of continuous discharge to 5 V was set as one cycle, and 200 cycles were repeated. The discharge capacity at the 200th cycle relative to the discharge capacity at the second cycle is shown in (Table 1) as an index of life characteristics.

Comparative Examples 1 and 2 in which the average particle size of the active material particles 21 deviated from the preferred range (0.1 to 10 μm), and the average particle size of the first carbon material 22 deviated from the preferred range (0.1 to 15 μm). And the average particle diameter ratio of the 2nd carbon material 23 with respect to the comparative examples 3 and 4 and the 1st carbon material 22 from which the average particle diameter of the 2nd carbon material 23 deviated from the suitable range (0.3-45 micrometers) is suitable. Comparative Examples 5 and 6 that deviated from the range (3 to 5 times) both showed a significant decrease in life characteristics. As the reason, in the case of the comparative example 2, since the surface area which participates in reaction falls, it is thought that the battery reaction was inactivated. In the case of Comparative Examples 1 and 3 to 6, since the filling property was lowered and the mixture layer 2 was remarkably peeled by the load during rolling, it is considered that a minute internal short circuit occurred. Furthermore, in the case of the comparative example 4, since the 2nd carbon material 23 is too large, it is thought that the dispersibility in the mixture layer 2 fell and the battery reaction was deactivated.

In contrast to these comparative examples, the lithium secondary batteries of the respective examples exhibited relatively good life characteristics. However, in Example 11 in which the surface roughness Ra of the mixture layer 21 is less than 0.4 μm, the diffusion characteristics of lithium ions are hindered due to the reduction in the reaction area, so that the life characteristics are slightly lowered as compared with Example 1. . On the contrary, in Example 15 in which the surface roughness Ra exceeds 3 μm, it was necessary to excessively perform the sand blasting process, so that a slight internal short circuit occurred due to the mixing of the scraped pieces of the mixture layer 21. In addition, the life characteristics were slightly deteriorated as compared with Example 1. Further, in Example 16 in which the thickness of the surface layer 3 was less than 1 μm, the volume of the surface layer 3 was excessively small, so that the electrolytic solution holding power was slightly reduced, and the life characteristics were slightly deteriorated as compared with Example 1. On the contrary, in Example 19 in which the thickness of the surface layer 3 exceeds 30 μm, the surface layer 3 itself becomes a reaction resistance, the reactivity at the electrode interface is lowered, and the life characteristics are slightly lowered as compared with Example 1.

  Since the present invention is indispensable for practical use of a lithium secondary battery aiming at high capacity, it is not only highly available but also highly useful.

Schematic sectional view showing a negative electrode for a lithium secondary battery of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Current collector 2 Mixture layer 3 Surface layer 21 Active material particle 22 1st carbon material 23 2nd carbon material 24 Binder 31 Solid particle

Claims (7)

Lithium secondary in which a mixture layer composed of active material particles that can be alloyed with lithium, a carbon material, and a binder is provided on a current collector, and a surface layer composed of solid particles is provided on the mixture layer A negative electrode for a battery,
The average particle diameter of the active material particles is 0.1 to 10 μm,
As the carbon material, using a first carbon material having an average particle diameter of 0.1 to 15 μm and a second carbon material having an average particle diameter of 0.3 to 45 μm,
The negative electrode for a lithium secondary battery is characterized in that the average particle size ratio of the second carbon material to the first carbon material is 3 to 5 times. The negative electrode for a lithium secondary battery according to claim 1, wherein at least a part of the surface of the active material particles is coated with a material having higher conductivity than the active material particles. 2. The negative electrode for a lithium secondary battery according to claim 1, wherein the mixture layer has a surface roughness Ra of 0.4 to 3 μm. 2. The negative electrode for a lithium secondary battery according to claim 1, wherein the surface layer has a function of holding an electrolytic solution and water-insoluble solid particles are used. The negative electrode for a lithium secondary battery according to claim 4, wherein an oxide containing at least one of aluminum, silicon, zirconium, and magnesium is used as the solid particles. The negative electrode for a lithium secondary battery according to claim 1, wherein the thickness of the surface layer is 1 to 30 μm. A lithium secondary battery using the negative electrode for a lithium secondary battery according to claim 1.