Achieving stable Na metal cycling via polydopamine/multilayer graphene coating of a polypropylene separator
Jieqiong Qin, Haodong Shi, Kai Huang, Pengfei Lu, Pengchao Wen, Feifei Xing, Bing Yang, Mao Ye, Yan Yu, Zhong‐Shuai Wu
Abstract
Abstract Sodium metal batteries are considered one of the most promising low-cost high-energy-density electrochemical energy storage systems. However, the growth of unfavourable Na metal deposition and the limited cell cycle life hamper the application of this battery system at a large scale. Here, we propose the use of polypropylene separator coated with a composite material comprising polydopamine and multilayer graphene to tackle these issues. The oxygen- and nitrogen- containing moieties as well as the nano- and meso- porous network of the coating allow cycling of Na metal electrodes in symmetric cell configuration for over 2000 h with a stable 4 mV overpotential at 1 mA cm −2 . When tested in full Na || Na 3 V 2 (PO 4 ) 3 coin cell, the coated separator enables the delivery of a stable capacity of about 100 mAh g −1 for 500 cycles (90% capacity retention) at a specific current of 235 mA g −1 and satisfactory rate capability performances (i.e., 75 mAh g −1 at 3.5 A g −1 ).