FIELD: electricity.
SUBSTANCE: invention relates to the auxiliary lithium ion battery and method of its production. The auxiliary lithium ion battery includes: a positive electrode sheet that includes a layer of a positive electrode active material comprising particles of positive electrode active material; a negative electrode sheet; and a non-aqueous electrolytic solution which comprises a compound containing fluorine, wherein the surface of the particles of the positive electrode active material includes a film containing fluorine and phosphorus, and the Cf/Cp ratio meets value of 1.89≤Cf/Cp≤2.61, where Cf represents the number of fluorine atoms in the film, and Cp represents the number of phosphorus atoms in the film.
EFFECT: invention is designed to increase the battery capacity under the cyclical impact of charging and discharging.
9 cl, 10 dwg, 5 tbl
