High Polarity Poly(vinylidene difluoride) Thin Coating for Dendrite-Free and High-Performance Lithium Metal Anodes

Abstract

The high-polarity £]-phase poly(vinylidene difluoride) (£]-PVDF), which has all trans conformation with F and H atoms located on the opposite sides of the polymer backbone, is demonstrated to be a promising artificial solid-electrolyte interphase coating on both Cu and Li metal anodes for dendrite-free Li deposition/stripping and enhanced cycling performance. A thin (?4 ?m) £]-PVDF coating on Cu enables uniform Li deposition/stripping at high current densities up to 5 mA cm ?2 , Li-plating capacity loadings of up to 4 mAh cm ?2 , and excellent cycling stability over hundreds of cycles under practical conditions (1 mA cm ?2 with 2 mAh cm ?2 ). Full cells containing an LiFePO 4 cathode and an anode of either £]-PVDF coated Cu or Li also exhibit excellent cycling stability. The profound effects of the high-polarity PVDF coating on dendrite suppression are attributed to the electronegative F-rich interface that favors layer-by-layer Li deposition. This study offers a new strategy for the development of dendrite-free metal anode technology. ? 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim