Optimization of Lithium Metal Battery Performance By Fluorinated Graphene/Polyacrylonitrile Composite Flexible Materials

Uncontrolled ion transport, fragile solid electrolyte interphase (SEI), and unstable lithium-plated microstructures in the anode are key factors inducing the growth of lithium dendrites and hindering the development of lithium metal batteries (LMBs). In this paper, a fluorinated graphene/polyacrylonitrile composite flexible material is simultaneously designed as the separator and the anode host, forming a comprehensive improved structure (optimized separator-SEI-host system) to enhance the LMB performance. The host and separator are modified with F, O-co-doped graphene, inducing the formation of a stable artificial SEI. Meanwhile, the Li+ transport behavior was improved, and the Li deposition was well-guided. Thanks to this exquisite design, 7000 h of dendrite-free cycling and a low polarization of 10 mV are achieved by the symmetric cell at 1 mA cm-2 and 1 mAh cm-2. At the same time, the full battery assembled with lithium iron phosphate established a 72% capacity retention and a 99.7% Coulombic efficiency after 1400 cycles. Moreover, impressive performances were also achieved when pairing with an NCM cathode. Our study demonstrates a strategy for LMB performance optimization, facilitating the practical application of LMB.