Non-aqueous electrolyte secondary battery, and battery pack obtained by connecting plurality of non-aqueous electrolyte secondary batteries

Abstract

A non-aqueous electrolyte secondary battery comprising an enclosure in which plural kinds of positive electrodes having a positive electrode active material; a non-aqueous electrolyte; a negative electrode containing a titanium compound as a main component of a negative electrode active material; and a separator held between the positive electrode and the negative electrode and formed from an electrical insulating material are enclosed, which comprises a separator-holding negative electrode which is held by the separator from both sides thereof and is disposed between one of the positive electrodes and the other one of the positive electrode adjacent thereto, the separator-holding negative electrode serving as the negative electrode, and wherein the plural kinds of the positive electrodes comprises a first positive electrode containing a layered rock salt compound as the positive electrode active material, and a second positive electrode whose main component is a positive electrode active material different in kind from the layered rock salt compound. According to the battery, even when the titanium compound is used for the negative electrode, the amount of gas generated during a cycle test is remarkably decreased, and the cycle stability is excellent.