| 摘要 |
PROBLEM TO BE SOLVED: To reduce a cost, enhance cycle characteristics and secure safety when overcharging as well as to stabilize a positive electrode active material itself, by using a positive electrode active material of a lithium nickel composite oxide having a rock-salt structure with orderly arranged layers obtained by substituting a part of a Ni site by other elements for the positive electrode and a negative electrode active material of a mixture of graphite and coke for the negative electrode. SOLUTION: The composition of a composite oxide for a positive electrode active material is shown by the formula LiNixM1yM2zO2z. (In the formula, Mi: At least one kind Selected from Co, Mn, M2: one or more kinds selected from Al, B, Fe, Cr, Mg; x+y+z=1, 0.5<x<0.95, 0.01<y<0.4, 0.001<z<0.2. A part of inexpensive Ni contained in the positive electrode active material is substituted by two or more elements to improve cycle characteristics. A negative electrode active material of a mixture of highly crystalline graphite and inexpensive coke increases a battery capacity, and suppresses a crystal from being collapsed by restricting a movement of a Li ion between both electrodes during normal charge and discharge. In addition, deposition of a dendrite on the negative electrode at the time of excessive charging is prevented by irreversible large capacity. |
