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Poor stability of lithium metal anodes in liquid electrolytes hinders its practical application in rechargeable batteries with very high energy density. Herein, we present an approach to tackle the intrinsic problems of Li metal anodes from the standpoint of separators. By a facile and versatile method based on mussel-inspired surface chemistry, a hybrid polydopamine/octaammonium POSS (PDA/POSS) coating was spontaneously formed on the surface of PE separators through the self-polymerization and strong adhesion feature of dopamine. This ultrathin PDA/POSS coating endows PE separators with different surface characteristics while keeping its microporous structure almost unchanged. The altered surface characteristics influence the separator/electrolyte interaction, and lead to remarkable enhanced ionic conductivity (from 0.36 mS cm −1 to 0.45 mS cm −1 ) and Li + ion transference number (from 0.37 to 0.47) of PE separators as well as the improved stability of lithium/electrolyte interface, which effectively decreases the electrode polarization and suppresses the lithium dendrites formation, contributing to superior C-rates capability and cycling performance of cells. [ABSTRACT FROM AUTHOR]

Low Li + ion transference number is one fatal defect of the liquid LiPF 6 electrolyte for Li-metal anode based batteries. This work aims to improve Li + ion transference number and ionic conductivity polyethylene (PE) separators. By a simple dip-coating method, the water-borne nanosized molecular sieve with 3D porous structure (ZSM-5) can be coated on PE separators. Especially, the Li + ion transference number is greatly enhanced from 0.28 to 0.44, which should be attributed to the specific pore structure and channel environment of ZSM-5 as well as the interaction between ZSM-5 and electrolyte. Compared with the pristine PE separator, the ionic conductivity of modified separators is remarkably improved from 0.30 to 0.54 mS cm −1 . As results, the C-rate capability and cycling stability are both improved. The Li-metal battery using the ZSM-5-modified PE separator keeps 94.2% capacity after 100 cycles. In contrast, the discharge capacity retention of the battery using pristine PE is only 74.7%. [ABSTRACT FROM AUTHOR]