Tuning the Unloading and Infiltrating Behaviors of Li-Ion by a Multiphases Gradient Interphase for High-Rate Lithium Metal Anodes.

Abstract

The random distribution of organic-phases (OPs) and inorganic-phases (IOPs) in native solid electrolyte interface (SEI) derived a sluggish Li-ion de-solvation and transmission, impairing the high-rate performance of lithium metal anodes (LMAs). Herein, a multiphases gradient distribution hybrid interface is constructed on metallic Li by surface chemical reconstruction. Theoretical simulations and experiments verify that the Li-ion unloading and infiltrating behaviors are tuned by functional complementary effects, enabling speedy kinetics. The upper OPs with polar functional group (─COO-) convert near-surface solvation structure, pushing Li-ion to unload the solvation cluster. Simultaneously, the bottom IOPs with plenty of crystal boundary accelerates Li-ion infiltration. Moreover, flexible OPs cooperate with rigid IOPs to buffer volume fluctuation and suppress dendritic Li growth. Consequently, the lifespan of the composited electrode is significantly prolonged over 520h at 5mAcm-2. The full cells also exhibit an exhilarated rate performance and capacity retention even under a low N/P ratio (≈2.5). This work offers a characteristic insight for the rational design of gradient hybrid interface on the practical LMAs.