Lithium Ion Repulsion-Enrichment Synergism Induced by Core-Shell Ionic Complexes to Enable High-Loading Lithium Metal Batteries.

Abstract

A core-shell additive with anionic Keggin-type polyoxometalate (POM) cluster as core and N-containing cation of ionic liquid (IL) as shell is proposed to stabilize Li-metal batteries (LMBs). The suspended POM derived complex in ether-based electrolyte is absorbed around the protuberances of anode and triggers a lithiophobic repulsion mechanism for the homogenization of Li+ redistribution. The gradually released POM cores with negative charge then enrich Li+ and co-assemble with Li. The Li+ repulsion-enrichment synergism can compact Li deposition and reinforce solid electrolyte interphase. This sustained-release additive enables Li∥Li symmetric cells with a long lifetime over 500 h and 300 h at high current densities of 3 and 5 mA cm-2 respectively. The complex additive is also compatible with high-voltage Li∥LiNi0.8 Co0.15 Al0.05 O2 (NCA) cells. Even with a NCA loading as high as ca. 20 mg cm-2 , the additive contained Li∥NCA cell can still cycle for over 100 cycles at 2.6 mA cm-2 .