Polycationic Polymer Layer for Air‐Stable and Dendrite‐Free Li Metal Anodes in Carbonate Electrolytes. Issue 12 (4th February 2021)

• Record Type: Journal Article
• Authors: Wu, Jingyi; Rao, Zhixiang; Liu, Xueting; Shen, Yue; Fang, Chun; Yuan, Lixia; Li, Zhen; Zhang, Wuxing; Xie, Xiaolin; Huang, Yunhui
• Is Part Of: Advanced materials. Volume 33:Issue 12(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-02-04
• Subjects: air‐stable and dendrite‐free Li metal anodes -- electrostatic shielding -- lithium metal batteries -- polycationic polymers; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.202007428
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: The short cycle life and safety concerns caused by uncontrollable dendrite growth have severely hindered the commercialization of lithium metal batteries. Here, a polycationic and hydrophobic polymer protective layer fabricated by a scalable tape‐casting method is developed to enable air‐stable, dendrite‐free, and highly efficient Li metal anodes. The polymeric cations of poly(diallyl dimethyl ammonium) (PDDA) provide an electrostatic shielding effect that unifies Li + flux at the surface of the Li anode and promotes a homogeneous Li plating, while the bis(trifluoromethanesulfonyl)imide (TFSI) anions bring hydrophobic characteristics and improve moisture stability. The accumulated TFSI anions by the polycationic film also facilitate the formation of a stable solid electrolyte interphase (SEI). Steady Li plating/stripping in the carbonate electrolyte can be achieved under a high areal capacity of 10 mAh cm −2 for 700 h with Li utilization efficiency up to 51.6%. LiNi0.8 Mn0.1 Co0.1 O2 and LiFePO4 cells using the modified anode exhibit much improved electrochemical performance compared with the bare Li counterpart. Moreover, ultrasonic imaging shows no gas generation in the modified Li/LiFePO4 pouch cell. Mechanism investigation demonstrates the stable SEI and homogeneous Li deposition derived by the polycationic layer. Abstract : A polycationic and hydrophobic polymer protective layer of Li metal is developed by a scalable tape‐casting method. Steady Li plating/stripping in commercial carbonate electrolyte can be achieved under a high areal capacity of 10 mAh cm −2 with Li utilization efficiency up to 51.6%. The modified Li also shows unaffected performance after exposure to ambient air or contact with water.