Negative pole piece, preparation method thereof and secondary battery

The invention belongs to the technical field of secondary batteries, and particularly relates to a negative pole piece, a preparation method of the negative pole piece and a secondary battery. The negative pole piece comprises a negative current collector, a negative active coating arranged on at least one surface of the negative current collector and a safety coating, the safety coating is arranged on one side surface, far away from the negative current collector, of the negative active coating, the safety coating comprises modified polyolefin particles, an inorganic filler, a binder and a cross-linking agent, and the weight part ratio of the modified polyolefin particles to the inorganic filler to the binder to the cross-linking agent is (90-110): (5-20): (10-20): (0.05-3). The negative pole piece disclosed by the invention can be expanded under a high-temperature condition, so that a gap is reduced, the resistance of the safety coating is increased, and short-circuit current is reduced or even cut off. In