Interfacial issues and dendritic Li deposition in lithium metal batteries (LMBs) hamper the practical application of liquid or solid-state cells. Here, a hybrid solid electrolyte interphase (SEI), based on hydroxyl-functionalized boron nitride (BN) nanosheets and poly(vinyl alcohol), is designed to solve the unstable nature of the Li anode-electrolyte interface. Rather than acquiring a rich Li halide environment through intense electrolyte decomposition, the hybrid SEI effectively regulates electrolyte decomposition and guarantees uniform Li plating via boosting interfacial Li+ ion transport at the interface. The Li+ ion boosting kinetics were deeply analyzed using simulations and spectroscopic analysis. It is revealed that the hydroxyl-functionalized BN can decrease kinetic energy barriers for Li+ ions and strongly holds TFSI- ions, thereby ensuring faster Li+ ion migration between electrodes and electrolytes. Tailoring the interfacial Li+ ion dynamics with hybrid SEI renders the Li transference number enhancement from 0.391 to 0.562 and 0.178 to 0.327 in liquid and solid-state cells, respectively. Moreover, Li symmetric cells with hybrid SEI exhibit an ultrahigh stability over 3500 h at 2 mA cm-2 with 2 mA h cm-2, along with the improved solid-state LMB performances. Our results suggest increasing Li+ ion transport at the interface is an alternative to resolve Li anode issues.
Keywords: boron nitride; dendrite-free; lithium anodes; lithium metal batteries; solid electrolyte interphase; solid-state electrolytes.