In order to improve the safety performance of the battery, in most of the prior arts, a manner of mixing materials with high safety in the slurry is adopted, which in most cases needs a high proportion of the materials with high safety so as to obtain the effect of significantly improving the safety of the battery. However, in the meantime of improving the safety, this manner selected will usually greatly reduce the energy density of the battery and increase the internal resistance of the battery when applied in low state of charge (State Of Charge, SOC). Besides, it is still difficult for this manner to prominently improve the safety of the battery with large capacity used in electric vehicles.
Additionally, in some other prior arts, in order to improve the safety of the battery, a manner of coating an active material layer on the positive electrode current collector and then coating another active material layer is adopted, however, this manner will lead to increasing of polarization of the battery and degeneration or even rapid slump of cycle performance.
However, the above-mentioned manners of improving the safety of the battery will deteriorate the performance and reliability of the battery, such as reducing energy density of the battery, increasing internal resistance of the battery and resulting in cycle slump and so on.