Functional polymers for lithium metal batteries

Rechargeable batteries that use Li metal as anode are regarded as the most viable alternative to state-of-the-art lithium ion batteries (LIBs), since Li metal batteries (LMBs) are capable of higher-density energy storage. The Nobel Prize in Chemistry 2019 awarded to J. B. Goodenough, S. M. Whittingham, and A. Yoshino for their contributions to the development of LIBs, drew increasing attention to the design of LMBs. Due to the highly reactive nature of metallic lithium and the need to tweak the design of cathode, electrolyte and anode, the industrial success of LMBs has yet to be achieved. In a battery cell, polymeric materials were traditionally used only as separators, cathode binders and packaging materials. In contrast, the enormous progress achieved in a century of polymer chemistry has enabled a large variety of application of polymers in numerous areas of material science. The design and implementation of functional polymers in LMBs is crucial to enhance their practical performance, safety and durability, paving the way to LMB commercialization. This review describes recent advances in the synthesis and tailoring of functional polymer materials to improve the stability of LMBs. The role and application of polymers in different parts of an LMB are presented, including anode, cathode, electrolyte and anode/electrolyte interphases.