Preparation method of secondary battery with high energy density and high safety

Abstract

The invention discloses a preparation method of a secondary battery with high energy density and high safety, and belongs to the technical field of secondary batteries. In order to solve the problems of low energy density, poor safety and the like of the lithium titanate negative electrode of the lithium ion secondary battery, the method comprises the following steps: taking a mixture of a high-capacity phosphorus-carbon negative electrode material and a carbon-based negative electrode material as a battery negative electrode active material; after a battery pole piece is prepared from the negative electrode active material, the battery pole piece, a battery positive plate and a diaphragm are assembled into a secondary battery cell, and after liquid injection and standing, formation is carried out in a proper voltage range, so that the lithium ion secondary battery with high energy density and high safety is obtained. Compared with 1.55 V vs.Li < + > / Li of a lithium titanate negative electrode, the first section lithium storage potential platform 0.5 V vs.Li < + > / Li of the phosphorus-carbon negative electrode material adopted by the invention is about 1.05 V lower than 1.55 V vs.Li < + > / Li, so that the upper limit voltage of the prepared total battery paired with the same positive electrode can be increased by about 1.05 V, and in practical application, the number of battery systems connected in series can be greatly reduced, and the integration cost of the battery system can be greatly reduced.