| 摘要 |
PURPOSE: To provide a seconrary battery whose Coulomb efficiency is enhanced and charge-discharge characteristic is not reduced by using an electrode using a carbon material where silicon exists on a surface as an active material, as a negative electrode. CONSTITUTION: A silicon element is made to exist on a surface of a carbon material such as carbon fiber by covering or the like. An electrode is formed by using this as an active material. This electrode is used as a negative electrode, and a secondary battery is formed by using nonaqueous electrolyte using lithium salt as electrolyte. A polyacrylonitrile baked body or the like is used as carbon fiber. As a positive electrode active material of this secondary battery, it is preferable to contain at least a lithium composite oxide. In the silicon element, the ratio of the silicon atom number to the carbon atom number is preferable to be in a range of 0.01 to 0.58 in respect of improving a charge- discharge characteristic. Therefore, an electrode by which reduction in discharge capacity at charging time after one day passes after charge and discharge is hardly caused and a secondary battery using its electrode, can be provided. |
