JP2007311279A - Nonaqueous electrolytic solution secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high capacity type nonaqueous electrolytic solution secondary battery having superior cycle characteristics and high temperature storing characteristics by improving dispersibility of composite particles which are negative electrode active materials, and by optimizing surfaces of carbonaceous materials which are source of conductivity. <P>SOLUTION: The nonaqueous electrolytic solution secondary battery is provided with a positive electrode, a negative electrode having the negative electrode active materials capable of reversibly storing and releasing lithium ions, and a nonaqueous electrolytic solution, and the negative electrode active materials are constituted by adhering the carbonaceous materials in which a surfactant is adsorbed to at least one part of the surface of metal oxide or semimetal oxide at one part of the surface. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a non-aqueous electrolyte secondary battery, and more particularly to a negative electrode for a non-aqueous electrolyte secondary battery.

  Non-aqueous electrolyte secondary batteries are lightweight and have high energy density, and are therefore used in various portable devices. Currently, carbon materials such as graphite are put into practical use as negative electrode active materials for non-aqueous electrolyte secondary batteries. However, its theoretical capacity density is 372 mAh / g. Therefore, silicon (Si), tin (Sn), germanium (Ge), and oxides and alloys thereof, which are alloyed with lithium, are being studied in order to further increase the energy density of nonaqueous electrolyte secondary batteries. . The theoretical capacity density of these negative electrode active material materials is larger than that of carbonaceous materials. In particular, silicon-containing particles such as Si particles and silicon oxide particles are widely studied because they are inexpensive.

  However, when these materials are used as the negative electrode active material and the charge / discharge cycle is repeated, the volume of the active material particles changes due to charge / discharge. This volume change makes the active material particles fine, and as a result, the conductivity between the active material particles decreases. Therefore, sufficient charge / discharge cycle characteristics (hereinafter referred to as “cycle characteristics”) cannot be obtained.

Therefore, it has been proposed to combine a plurality of carbonaceous materials (mainly carbon fibers) into composite particles by using an active material containing a metal or metalloid capable of forming a lithium alloy as a core. In this configuration, it has been reported that conductivity is ensured and cycle characteristics can be maintained even if the volume of the active material changes (for example, Patent Document 1).
JP 2004-349056 A

  The composite particles described above are usually formed as a negative electrode by forming a mixture layer by applying a solvent to a current collector and then applying the mixture to a current collector. However, when the technique of Patent Document 1 is used, the carbonaceous material has low wettability with respect to the solvent of the paint, so that the dispersibility of the composite particles is reduced, and the composite particles are unevenly distributed in the mixture layer. When a non-aqueous electrolyte secondary battery using this negative electrode is charged / discharged, lithium is likely to be selectively occluded and released only in a part of the composite particles, the deterioration is partially promoted, and the cycle characteristics are lowered. Furthermore, if the surface area of the carbonaceous material on the surface of the negative electrode active material is excessive, there is a problem in that gas generation during high-temperature storage is correspondingly increased and the internal pressure of the battery tends to increase. These two problems are remarkable when the carbonaceous material has a large surface area.

  The present invention is for solving the above-mentioned problems, and by improving the dispersibility of the composite particles as the negative electrode active material, by optimizing the surface of the carbonaceous material as the conductive source, an excellent cycle is achieved. The present invention provides a high capacity type non-aqueous electrolyte secondary battery having characteristics and high-temperature storage characteristics.

  In order to solve the above-described problems, a non-aqueous electrolyte secondary battery of the present invention includes a positive electrode, a negative electrode having a negative electrode active material capable of reversibly occluding and releasing lithium ions, and a non-aqueous electrolyte including a non-aqueous electrolyte. An electrolyte secondary battery comprising a carbonaceous material adsorbed with a surfactant on a part of the surface and attached to at least a part of the surface of the metal oxide or metalloid oxide. Characterized by substance.

  Metal oxides or metalloid oxides are high-capacity negative electrode active materials, but have poor conductivity because they are easily pulverized. Conductivity can be secured by adhering a carbonaceous material to at least a part of the surface, but it has poor dispersibility when forming the negative electrode and becomes a gas generation source during high-temperature storage. Therefore, by adsorbing the surfactant to a part of the surface of the carbonaceous material, the wettability of the carbonaceous material with respect to the solvent used for coating is improved and the dispersibility is improved, and the uneven distribution in the negative electrode mixture layer The cycle characteristics are improved by suppressing the crystallization. Furthermore, since the surfactant adsorbed on the carbonaceous material blocks the gas generation reaction during high temperature storage, it is possible to avoid deformation of the battery and release of the nonaqueous electrolytic solution to the outside.

  According to the present invention, since the cycle characteristics and high-temperature storage characteristics of a negative electrode active material having a large theoretical capacity can be enhanced, a practical and high capacity non-aqueous electrolyte secondary battery can be provided.

  The present invention will be described in detail below with reference to the drawings.

  A first invention is a non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode having a negative electrode active material capable of reversibly occluding and releasing lithium ions, and a non-aqueous electrolyte, wherein a part of the surface A negative electrode active material is characterized in that a carbonaceous material adsorbed with a surfactant is attached to at least a part of the surface of a metal oxide or metalloid oxide.

  As shown in the schematic diagram of FIG. 1, the negative electrode active material of the first invention includes composite particles in which a carbonaceous material 2 is attached to a part of the surface of a metal oxide or metalloid oxide 1. Furthermore, a surfactant 5 having both an adsorption site 3 and a non-adsorption site 4 for the carbonaceous material 2 is adsorbed on a part of the surface of the carbonaceous material 2.

  As described above, the metal oxide or metalloid oxide 1 has a high capacity, but is poor in conductivity because it is easily pulverized. Conductivity can be secured by adhering the carbonaceous material 2 to at least a part of the surface of the metal oxide or metalloid oxide 1, but the dispersibility in the negative electrode mixture layer is poor, and gas generation during high-temperature storage is achieved. The source. Therefore, by adsorbing the surfactant 5 on a part of the surface of the carbonaceous material 2, the wettability of the carbonaceous material 2 with respect to the solvent used for coating is improved and the dispersibility is enhanced. This is because the affinity for the solvent is increased at the non-adsorption site 4 in the surfactant 5. This effect can eliminate the uneven distribution of the composite particles inside the negative electrode mixture layer, thereby improving the cycle characteristics. Furthermore, since the surfactant 5 adsorbed on the carbonaceous material 2 blocks the gas generation reaction during high temperature storage, it is possible to avoid deformation of the battery and release of the non-aqueous electrolyte to the outside.

  The metal oxide or metalloid oxide 1 includes Si, Ge, Sn, Pb, Mn, Fe, Co, Ni, Cu, Zn, Ag, Al, Zn, Mg, and Cd from the viewpoint of occluding and releasing a large amount of lithium. Further, it is possible to use a metal oxide or a semimetal oxide selected from Mg and Mg alone, or an alloy or a compound and a mixture with another metal.

Examples of the carbonaceous material 2 include activated carbon, graphite carbon, amorphous carbon, carbon fiber, artificial graphite, flake graphite, spherical graphite obtained by graphitizing mesophase spherules, carbon nanofiber (CNF), CNF. A modified composite material, a carbon nanotube (CNT), a CNT-modified composite material, or the like sintered alone or mixed can be used, and can be attached to the surface of a metal oxide or a semi-metal oxide. In addition, since the larger the specific surface area, the easier it is to impart conductivity to the composite particles and the greater the effect of the surfactant, the carbonaceous material used for the negative electrode active material is activated carbon, flake graphite, carbon fiber, CNF. CNF-modified composite material, CNT, and CNT-modified composite material are preferable.

  As the surfactant 5, an anionic surfactant, a nonionic surfactant, a zwitterionic surfactant, or a cationic surfactant can be used. Although the mechanism by which the surfactant 5 is adsorbed on the surface of the carbonaceous material 2 will be described in detail later, since the exposed area of the carbonaceous material 2 used as a gas generation field during high-temperature storage is controlled by the surfactant 5, Gas generation amount can be suppressed.

  The second invention is characterized in that, in the first invention, the carbonaceous material 2 is fibrous. As described above, the carbonaceous material 2 is used for imparting electrical conductivity. However, when the metal oxide or metalloid oxide 1 is pulverized, the carbonaceous material 2 is entangled with each other to easily secure a conductive network. The carbonaceous material 2 is more preferably fibrous. Examples of such fibrous carbonaceous material 2 include carbon fiber, CNF, CNF-modified composite material, CNT, and CNT-modified composite material.

  The third invention is characterized in that, in the first invention, the surfactant 5 covers 0.1 to 70% of the carbonaceous material 2. When the coating degree of the surfactant 5 is less than 0.1% with respect to the carbonaceous material 2, the wettability of the carbonaceous material 2 with respect to the solvent used at the time of preparing the paint is not sufficient, and the dispersibility of the composite particles is slightly lowered. The cycle characteristics are slightly degraded. Furthermore, the gas generation reaction through the surface of the carbonaceous material 2 slightly increases during high temperature storage. On the other hand, when the covering degree of the surfactant 5 exceeds 70% with respect to the carbonaceous material 2, the exposed area of the carbonaceous material 2 is slightly insufficient, so that the conductive network through the surface of the carbonaceous material 2 becomes insufficient. The cycle characteristics are slightly deteriorated. The degree of coverage of the surfactant 5 on the carbonaceous material 2 can be confirmed by measuring the electric double layer capacity and specific surface area of the electrode using the carbonaceous material 2.

  A fourth invention is characterized in that, in the first invention, the surfactant 5 includes any one of anionic, amphoteric, and nonionic surfactants, or a mixture of two or more thereof. At the time of coating formation, the surface of the metal oxide or metalloid oxide 1 is negatively charged, while the carbonaceous material 2 is positively charged in a manner repelling it. The above three surfactants 5 are adsorbed on the carbonaceous material 2 by the adsorption sites 3 each having a negative charge as shown below, whereby the composite particles are unevenly distributed in the negative electrode mixture layer. Is suppressed.

  In the case of an anionic surfactant, it dissociates into an anion and a cation in the paint. Here, the portion of the anion that is the binding site with the cation is adsorbed to the carbonaceous material 2 as the adsorption site 3, while the opposite side is adsorbed to the solvent constituting the paint as the non-adsorption site 4, thereby dispersing the composite particles in the paint. Therefore, uneven distribution of the composite material can be suppressed.

  In the case of a zwitterionic surfactant, both anion and cation sites exist in one molecule. Here, while the anion site is adsorbed on the carbonaceous material 2 as the adsorption site 3, the dispersibility of the composite particles in the paint is improved because the opposite side has affinity with the solvent constituting the paint as the non-adsorption site 4. Uneven distribution of the material can be suppressed.

  In the case of a nonionic surfactant, the lipophilic group in the molecule is not ionized in the solution but is adsorbed on the carbonaceous material 2 as the adsorption site 3, while the dispersibility of the composite particles in the coating is caused by repulsion between the hydrophilic groups. Since it improves, the uneven distribution of a composite material can be suppressed. In addition, since nonionic surfactants are not ionized, interference with metal ions can be ignored even in the presence of metal ions as in the case of anionic surfactants.

On the other hand, in the case of a cationic surfactant, it dissociates into an anion and a cation in the paint, but the site of the cation binding site with the anion is not the carbonaceous material 2 but the metal oxide or semi-metal oxide as the adsorption site 3. Since it is selectively adsorbed by the negative charge on the surface of 1, the occlusion and release reaction of lithium performed on the surface of the metal oxide or metalloid oxide 1 is inhibited. Further, as representative cationic surfactants, quaternary ammonium alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, amine salt N-methylbishydroxyethylamine fatty acid esters and hydrochlorides, etc. However, it is not preferable because many of them contain a halogen element and gas such as hydrogen chloride or hydrogen fluoride is easily generated.

  The outline of the nonaqueous electrolyte secondary battery of the present invention will be described in more detail.

  The non-aqueous electrolyte secondary battery of the present invention includes a positive electrode, a negative electrode, and a non-aqueous electrolyte that can reversibly store and release lithium ions.

The positive electrode active material of the non-aqueous electrolyte secondary battery according to the present invention is not particularly limited as long as it is a material capable of reversibly occluding and releasing lithium ions. For example, LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiMnO ₂ , Li _x TiS ₂ , Li _x V ₂ O ₅ , V ₂ MoO ₈ , MoS ₂ , LiFePO ₄ or the like can be used. Among them, NiNi of LiNiO ₂ and LiNiO ₂ having a large theoretical capacity having a crystal structure similar to that of LiCoO ₂ of a Co-based material having a layered rock salt structure that is relatively easy to synthesize with Mn, Al, Co, etc. Substituted materials such as LiMn ₂ O ₄ having a spinel structure, LiMnO ₂ having an orthorhombic or monoclinic structure, and LiFePO ₄ having an olivine structure are desirable.

  The metal oxide or metalloid oxide 1 is not particularly limited as long as it can occlude and release lithium. For example, Si, Ge, Sn, Pb, Mn, Fe, Co, Ni, Cu, Zn, Ag, Al It is possible to contain an oxide of an element selected from Zn, Mg, Cd and Mg as a single substance or a mixture of two or more. Among them, Si and Sn oxides having a large capacity are preferably used.

  The negative electrode active material of the present invention is obtained by mixing a metal oxide or semi-metal oxide 1 with a binder and further mixing a carbonaceous material 2, thereby converting the carbonaceous material 2 into a metal oxide or semi-metal oxide 1. And then sintered at 400 to 3000 ° C. in a reducing atmosphere or an inert atmosphere.

  A method for producing the nonaqueous electrolyte secondary battery of the present invention will be described.

  As a method for producing a positive electrode and a negative electrode, the positive electrode and the negative electrode can be obtained by dispersing each active material in a solvent to form an electrode paste, and applying and drying to a current collector.

  The electrode paste can contain a binder. Binders include polyacrylic acid (PAA), modified acrylic rubber, fluororesins such as polyvinylidene fluoride (PVDF), diene rubbers such as styrene butadiene rubber (SBR), polyvinylacetamide (PNVA), polyacrylic acid, etc. Can be used alone or in combination of two or more. In addition, in the case of the negative electrode, the addition amount of the binder is preferably 0.1% by weight to 20% by weight with respect to the total weight of the active material. Further, various dispersants, stabilizers and the like can be added as necessary. The solvent of the electrode paste is not particularly limited, but water, N-methyl-2-pyrrolidone (NMP), cyclohexane, N, N-dimethylformamide, tetrahydrofuran, acetone, methanol, ethanol, propanol, methyl ethyl ketone, etc. alone or in combination A mixture of the above can be used.

For the method of applying the electrode paste to the current collector, for example, any thickness and any shape using means such as roller coating such as applicator roll, screen coating, doctor blade method, transfer method, spin coating, bar coder, etc. Although it is desirable to apply | coat to, it is not limited to these. Which method should be used must be individually selected according to the fluidity of the electrode paste and the binding property of the electrode paste to the current collector.

  The current collector can be arbitrarily selected as long as it is an electronic conductor that does not adversely affect the constructed battery. For example, although copper, nickel, aluminum, stainless steel, molybdenum, etc. are mentioned, it is preferable that it is formed from the material which does not alloy with lithium, and copper is mentioned as a particularly preferable material. The current collector is preferably thin, and particularly preferably 5 μm to 100 μm. Examples of such copper foil include electrolytic copper foil. Electrolytic copper foil, for example, immerses a metal drum in a non-aqueous electrolytic solution in which copper ions are dissolved, and allows current to flow while rotating it, thereby depositing copper on the surface of the drum and peeling it off It is the copper foil obtained. Furthermore, if necessary, the electrode paste can be applied to a current collector, dried, and then rolled by a roller press or the like.

  The non-aqueous electrolyte according to the present invention is prepared by dissolving a non-aqueous electrolyte in a non-aqueous solvent. Examples of the non-aqueous solvent include ethylene carbonate (EC), ethyl methyl carbonate (EMC), propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyl lactone, 1,2-dimethoxymethane, 1,2-dichloroethane. 1,3-dimethoxypropane, 4-methyl-2-pentanone, 1,4-dioxane, acetonitrile, propionitrile, butyronitrile, benzonitrile, sulfolane, 3-methyl-sulfolane, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, dimethyl Formamide, trimethyl phosphate, triethyl phosphate and the like can be used. These non-aqueous solvents can be used alone or in admixture of two or more.

  Further, examples of the electrolyte contained in the nonaqueous electrolytic solution according to the present invention include lithium such as lithium perchlorate, lithium hexafluorophosphate, lithium borofluoride, lithium hexafluoroarsenide, and lithium trifluorometasulfonate. A salt can be used.

  The shape of the non-aqueous electrolyte secondary battery of the present invention may be any of coin type, button type, sheet type, laminated type, cylindrical type, flat type, square type, large size used for electric vehicles, etc. .

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to the following description.

Example 1
(I) Production of Positive Electrode As a positive electrode active material, Li ₂ CO ₃ and Co ₃ O ₄ were mixed at a molar ratio of 3: 2, and baked to synthesize LoCoO ₂ . 5 parts by weight of acetylene black as a conductive material and 10 parts by weight of PVDF as a binder were mixed with 100 parts by weight of LiCoO ₂ thus obtained. Next, this mixture was suspended in an equivalent amount of N-methyl-2-pyrrolidone (NMP) to LiCoO ₂ to obtain a positive electrode paste. The aluminum foil having a thickness of 20 μm was used as a current collector, the positive electrode paste was applied onto the current collector with a doctor blade, dried at 120 ° C. for 60 minutes, and rolled using a pair of stainless steel rollers, and then 10 mm. It cut | judged in * 10mm and was set as the positive electrode.

(Ii) Production of negative electrode active material SiO ₂ and CNF manufactured by Showa Denko KK were mixed in an NMP solution of PVDF as a binder, and carbon nanofibers were bound to the surface of SiO ₂ . This was sintered at 1500 ° C. in an argon atmosphere to obtain a negative electrode active material.

(Iii) Preparation of negative electrode An aqueous solution of sodium laurate, which is an anionic surfactant, was prepared, and the negative electrode active material was adjusted so that the amount of surfactant was 0.18 g per 1 m ² of the surface area of the negative electrode active material described above. Was added and stirred. Furthermore, as a binder, 20 parts by weight of PAA having an average molecular weight of 100,000 was added to 100 parts by weight of the negative electrode active material and kneaded to prepare a negative electrode paste by setting the solid content of the negative electrode paste to 40%. Then, a 15 μm thick copper foil was used as a current collector, and a negative electrode paste was applied to the current collector by a doctor blade method so that the total thickness of the dried current collector and the negative electrode mixture layer was 100 μm. And dried at 120 ° C. for 60 minutes. Furthermore, the dried negative electrode was cut into 10 mm × 10 mm to obtain a negative electrode.

  The negative electrode of Example 1 was measured by time-of-flight mass spectrometry (TOF-SIMS), and the coverage of the surfactant with respect to the carbonaceous material on the surface of the negative electrode active material was determined by the amount of ions having the molecular structure of the surfactant. As a result, it was 0.1%.

(Iv) Preparation of non-aqueous electrolyte A non-aqueous electrolyte was prepared by dissolving 1 mol / liter (1.0 M) of LiPF ₆ in a solvent in which EC and EMC were mixed at a volume ratio of 1: 3.

(V) Production of Battery An aluminum lead was welded to the positive electrode, and a nickel lead was welded to the negative electrode. Next, it is wound between a positive electrode and a negative electrode through a separator made of a polyethylene microporous film, inserted into a bag-like aluminum laminate film (inner size 35 mm width), and then injected with 1 ml of a non-aqueous electrolyte. Then, the open end of the aluminum laminate film was heat sealed to produce a non-aqueous electrolyte secondary battery. This is Example 1.

(Example 2)
A nonionic polyoxyethylene alkyl ether is used as the surfactant, and the negative electrode active material is added so that the amount of the surfactant is 0.1 g per 1 m ² of the surface area of the negative electrode active material. Produced. A nonaqueous electrolyte secondary battery produced in the same manner as in Example 1 except that this was used is referred to as Example 2. In addition, it was 2.7% as a result of calculating | requiring the coverage of the surfactant with respect to the carbonaceous material of the negative electrode active material surface similarly to Example 1. FIG.

(Example 3)
A nonionic polyoxyethylene sorbitan fatty acid ester is used as the surfactant, and the negative electrode active material is added so that the amount of the surfactant is 20 g per 1 m ² of the surface area of the negative electrode active material to produce a negative electrode paste. did. A nonaqueous electrolyte battery produced in the same manner as in Example 1 except that this was used is referred to as Example 3. In addition, it was 35.6% as a result of calculating | requiring the coverage of the surfactant with respect to the carbonaceous material of the negative electrode active material surface similarly to Example 1. FIG.

Example 4
A zwitterionic sodium alkylamino fatty acid was used as the surfactant, and the negative electrode active material was added so that the amount of the surfactant was 10 g per 1 m ² of the surface area of the negative electrode active material to prepare a negative electrode paste. A non-aqueous electrolyte battery produced in the same manner as in Example 1 except that this was used is referred to as Example 4. In addition, it was 70% as a result of calculating | requiring the coating rate of surfactant with respect to the carbonaceous material of the negative electrode active material surface similarly to Example 1. FIG.

(Examples 5-7)
As the surfactant, sorbitan fatty acid ester (solvent: ethanol) which is a nonionic surfactant is used, and the amount of the surfactant is 3 g (Example 5) and 0.15 g per 1 m ² of the surface area of the negative electrode active material ( The negative electrode active material was added so that it might become Example 6) and 14g (Example 7), and the negative electrode paste was produced. Except having used this, the nonaqueous electrolyte battery produced similarly to Example 1 is made into Examples 5-7. As in Example 1, the surfactant coverage on the carbonaceous material on the surface of the negative electrode active material was determined. As a result, 13.3% (Example 5), 0.09% (Example 6), and 70. It was 8% (Example 7).

(Comparative Example 1)
A non-aqueous electrolyte secondary battery is referred to as Comparative Example 1 as in Example 1 except that only SiO ₂ is used as the negative electrode active material.

  Each battery described above was evaluated as follows. The results are shown in (Table 1).

(Cycle characteristics)
After constant current charging at 2 mA until reaching 4.2 V, constant voltage charging was further performed until reaching 0.2 mA, and after a pause of 30 minutes, constant current discharging was performed at 1 mA until 3.0 V was reached. . This charge / discharge was repeated, and the ratio of the discharge capacity at the 50th cycle to the discharge capacity at the 2nd cycle was determined as the “capacity maintenance ratio”. The results are shown in (Table 1).

(High temperature storage characteristics)
Charging was performed for 4 hours at an environmental temperature of 20 ° C., a constant voltage of 4.2 V, and a limiting current of 2 mA. These batteries in a charged state were discharged at a constant current of 1 mA, and this was repeated for 3 cycles, and then only the charge was performed in the fourth cycle. After leaving for 6 hours in an environment of 40 ° C., a hole was made in one end of the aluminum laminate film of each battery, and the gas inside the battery was collected in a non-aqueous electrolyte. The amount of collected gas (cm ³ ) is shown in (Table 1).

実施例１〜７は、比較例１と比べて容量維持率が高くなっている。この理由として負極合剤層中の負極活物質の分散性が界面活性剤の作用によって向上していることが挙げられる。その効果は負極活物質表面の炭素質材料に対する界面活性剤の被覆率が０．１％以上の場合に顕著であるが、この被覆率が７０％を超えるとＳｉＯ₂のリチウム吸蔵放出反応が阻害されるために、かえってややサイクル特性が低下する傾向が見られた。

In Examples 1 to 7, the capacity retention rate is higher than that of Comparative Example 1. This is because the dispersibility of the negative electrode active material in the negative electrode mixture layer is improved by the action of the surfactant. The effect is remarkable when the coverage of the surfactant to the carbonaceous material on the surface of the negative electrode active material is 0.1% or more, but when this coverage exceeds 70%, the lithium occlusion / release reaction of SiO ₂ is inhibited. As a result, there was a tendency for the cycle characteristics to decrease rather.

In Examples 1 to 7, the amount of gas collected is smaller than that of Comparative Example 1. The reason for this is that the generation of gas during charging and discharging is suppressed by selectively adsorbing and coating the surface of the carbonaceous material of the negative electrode active material. The effect was remarkable when the coverage of the surfactant with respect to the carbonaceous material on the surface of the negative electrode active material was 0.1% or more.

  The non-aqueous electrolyte secondary battery of the present invention has a higher capacity than conventional batteries and exhibits well-balanced battery characteristics. Therefore, the non-aqueous electrolyte secondary battery is highly usable as a power source for various fields such as notebook computers, mobile phones, and digital cameras. And useful.

Schematic showing the negative electrode active material of the present invention

Explanation of symbols

1 Metal oxide or metalloid oxide 2 Carbonaceous material 3 Adsorption site 4 Non-adsorption site 5 Surfactant

Claims (4)

A non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode having a negative electrode active material capable of reversibly occluding and releasing lithium ions, and a non-aqueous electrolyte,
Non-aqueous electrolysis characterized in that the negative electrode active material is configured by adhering a carbonaceous material having a surfactant adsorbed on a part of the surface to at least a part of the surface of the metal oxide or semi-metal oxide. Liquid secondary battery. The non-aqueous electrolyte secondary battery according to claim 1, wherein the carbonaceous material is fibrous. The non-aqueous electrolyte secondary battery according to claim 1, wherein the surfactant covers 0.1 to 70% of the carbonaceous material. 2. The non-aqueous composition according to claim 1, wherein the surfactant contains any one of an anionic surfactant, a zwitterionic surfactant, and a nonionic surfactant as a single type or a mixture of two or more types. Electrolyte secondary battery.

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