POSITIVE POLE PIECE, AND LITHIUM ION BATTERY, BATTERY MODULE, BATTERY PACK AND DEVICE USING POSITIVE POLE PIECE

摘要

Disclosed are a positive pole piece (521), and a lithium ion battery (5), a battery module (4), a battery pack (1) and a device using the positive pole piece (521). The lithium ion battery (5) includes the positive pole piece (521), a negative pole piece, a separator and an electrolyte. The positive pole piece (521) includes a positive electrode current collector (521a) and a positive electrode active substance layer (521b) disposed on the surface of the positive electrode current collector (521a) and containing a positive electrode active material; an inorganic dielectric layer (521c) without a binder is disposed on the surface of the positive electrode active substance layer (521b); and the resistance of the positive pole piece (521) is not higher than 8 ohm. Due to the good chemical stability of the inorganic dielectric layer (521c), same can exist stably under a high voltage, which can slow down the surface structure change of the active substance caused by an excessively high voltage of the positive electrode active material, improve the stability of the positive electrode material, at the same time effectively isolate the strong oxidizing positive electrode active substance in direct contact with the less stable additives, solvents and the outer surface of the separator in the electrolyte, reduce the gas production amount of the lithium ion battery (5), and prevent the surface polymer of the separator from failing under a high voltage; and the resistance of the positive pole piece (521) being not higher than 8 ohm is beneficial to ensure that the battery has a lower internal resistance, less polarization, and better cycling performance and rate performance.