材料科学
法拉第效率
阳极
电解质
锂(药物)
X射线光电子能谱
化学工程
成核
电极
物理化学
化学
医学
工程类
内分泌学
有机化学
作者
Ke Zhang,Feng Wu,Kun Zhang,Suting Weng,Xinran Wang,Mingda Gao,Yahui Sun,Dong Cao,Ying Bai,Huajie Xu,Xuefeng Wang,Chuan Wu
标识
DOI:10.1016/j.ensm.2021.06.023
摘要
Lithium metals offer great promises to achieve higher energy density beyond conventional lithium-ion batteries (LIBs) because of its ultrahigh specific capacity (3860 mAh g−1) and the lowest reduction potentials (-3.04 V vs. standard hydrogen electrode). Unfortunately, the application of lithium metal anode has been long-standingly handicapped by uncontrollable dendrite growth, which induces instable solid electrolyte interface (SEI), performance degradation and thermal runaway. Herein, a compositionally favorable and structurally robust dual-protective layer (DPL) is proposed, where at the bottom, in-situ formed LiCl film provides sufficient rigidity (6.5 GPa) and low Li+ diffusion barriers (0.09 eV) against dendrite growth. The poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) gel-electrolyte as the top layer is rationally selected with high flexibility to accommodate volume variation. Due to the synergy of DPL, the instability of interface is ultimately regulated to favor an extremely stabilized SEI with enhanced Li+ diffusion kinetics. Depth profiling of X-ray photoelectron spectroscopy (XPS) revealed a spontaneously-formed gradient SEI hierarchy, a first-of-this-kind structure that enables long-term cycle stability and high rate capability. Cryo-electron microscopy (cryo-EM) provides direct proof on the formation of halide-rich SEI interlayers that strengthen the interfacial stability during cycles. As a consequence, dendrite-proof lithium deposition, critical Li+ flux and fast ion-diffusion kinetics have been synergistically achieved to greatly improve the high-rate cycle stability (10 mA cm−2), high Coulombic efficiency (99.5%), and prolonged cycle lifespan (1600 h) for lithium metal batteries (LMBs). The design of DPL from this contribution has opened up opportunities of lithium chlorides in purpose of constructing dendrite-free and Li+ permeable interface, and provided insights for the realization of high energy density LMBs.
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