Secondary battery
A secondary battery includes a negative electrode containing a lithium silicate phase and silicon particles dispersed in the lithium silicate phase and an electrolytic solution containing a fluorine-containing linear carboxylic acid ester represented by R 1 —(CO)O—CH 2 —R 2 (wherein R 1 is an alkyl group and R 2 is an alkyl group in which at least one hydrogen atom is substituted with fluorine).
1. A secondary battery comprising a negative electrode containing a silicon composite particle which includes a lithium silicate phase and silicon particles dispersed in the lithium silicate phase, and
an electrolytic solution containing a fluorine-containing linear carboxylic acid ester represented by R 1 —(CO)O—CH 2 —R 2 (wherein R 1 is an alkyl group and R 2 is an alkyl group in which at least one hydrogen atom is substituted with fluorine),
wherein the electrolytic solution further contains 2-chloro-1,1-difluoroethyl-2,2,2-trifluoroethyl ether.
2. The secondary battery according to claim 1 , wherein the fluorine-containing linear carboxylic acid ester contains 2,2,2-trifluoroethyl acetate.
3. The secondary battery according to claim 1 , wherein the electrolytic solution further contains methyl 3,3,3-trifluoropropionate.
4. The secondary battery according to claim 1 , wherein, in the lithium silicate phase, a half-width of a diffraction peak of a (111) plane of lithium silicate phase in an XRD pattern measured through X-ray diffraction analysis is 0.05° to 0.55°.
5. The secondary battery according to claim 1 , wherein at least a portion of a surface of the silicon composite particle is coated with a conductive material.