A polymer brush-based robust and flexible single-ion conducting artificial SEI film for fast charging lithium metal batteries

Lithium metal anode has attracted wide research interests because of its very high theoretical capacity and low potential. However, severe safety issues arising from lithium dendrite growth have gripped the throat of the practical application of lithium metal batteries. Herein, a novel superstructured single-ion conducting polymer brush (CNF-g-PSSLi) is proposed as artificial solid electrolyte interphase (SEI) film to inhibit the lithium dendrite growth. The as-obtained CNF-g-PSSLi integrates merits of robust CNF backbone nanonetwork, brush-improved interfacial compatibility, -SO3− group-guided rapid transportation of lithium ions, and -SO3− group-induced electrostatic repulsion against initially formed lithium dendrites. As a result, CNF-g-PSSLi film exhibits good mechanical properties (elasticity modulus = 5.3 GPa) against dendrite growth upon cell cycling, comfortable interfacial contact, and fast ionic transport. Symmetric Li|Li cells with CNF-g-PSSLi as artificial SEI show outstanding plating/stripping stabilities at ultrahigh current densities (20 mA cm−2). In addition, Li|LiFePO4 full cell with Li@CNF-g-PSSLi anode exhibits a long lifespan (300 cycles) with a tiny capacity decay of 0.08% per cycle at a high current density of 5 C. This work could provide an efficient attempt to develop superior artificial SEI films by well-orchestrated macromolecular engineering.