In-situ growth poly(N-methylaniline) coating on sulfur cathode for lithium-sulfur battery

Lithium-sulfur batteries are considered to be the most promising high-energy-density storage system, yet the dissolution of polysulfides during the charging process limits the utilization, and cycle stability of active materials, which affects the practical application of lithium-sulfur batteries. Herein, a poly(N-methylaniline) (PMAn) coating film is formed in situ on the cathode surface by electrochemically polymerizing the monomer of N-methylaniline(MAn) contained in the electrolyte during film formation process. The PMAn coating film on the surface of the cathode can prevent the dissolution of polysulfide, then reduce the loss of active material, and slow the oxidation of polysulfide by lithium nitrate, resulting in improved cycle stability. As a result, the lithium-sulfur battery with 0.5 wt% MAn render an initial discharge specific capacity of 1224 mAh/g and a capacity retention of 63.79% for 200 cycles, which is better than the performance of the battery without MAn.