| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a battery that obtains excellent cycle characteristics and swelling characteristics. <P>SOLUTION: The battery includes a negative electrode 21, an positive electrode 22 and an electrolyte solution as well, and the electrolyte solution is impregnated into the separator 23 which is arranged between the negative electrode 21 and the positive electrode 22. An positive electrode active material layer 22B of the positive electrode contains a plurality of positive electrode active material particles and the positive electrode active material particle contains silicon and a multilayer structure inside the particle. The electrolyte solution contains cyclic carbonic acid ester which has halogen as a solvent, tetrafluoroborate lithium as an electrolyte salt, and a unsymmetrical ester compound which, while having a methyl group at one end, has an alkyl group (carbon number =2-4) at the other end. Since the electrolyte solution becomes hard to be decomposed even if charging/discharging is repeated, a discharging capacity becomes hard to be reduced and a secondary battery becomes hard to swell. <P>COPYRIGHT: (C)2009,JPO&INPIT |
