Cross-Linking Surface Chemistry Regulation by an Ionic Complex Anchored Interlayer for Stable Li Metal Batteries

Abstract

Lithium (Li) metal batteries (LMBs) using a Li anode and nickel (Ni)-rich cathode constitute a promising powering solution for long-range electric vehicles. Unfortunately, both the Li anode and Ni-rich cathode suffer from surface deterioration-related failures. Herein, an ionic complex-anchored interlayer consisting of positively charged skeletons with conjugated π bonds, Li⁺ ions, and functional anions is investigated to trigger a cross-linked surface chemistry regulation in LMBs. It is revealed that the Li⁺ and anions electrostatically anchored on the interlayer can be released to alter the crossover electrochemistry of LMB for durable electrode interphases. Furthermore, by presetting the interlayer on a carbonaceous scaffold, an extended delocalization path of π electrons enables uniform adsorption of the anions, while the prelithiated carbon scaffold by Li⁺ from the interlayer facilitates the anion decomposition to form a robust bilayer surface, affording reversible Li plating/stripping with high average coulombic efficiency beyond 99.5% over 500 cycles. Simultaneously, the modified cathode interphase withstands structural stability of the Ni-rich materials and mitigates current collector corrosion efficiently. These merits lead to significantly enhanced performance of LMBs, where stable cycling over 150 cycles is achieved for an anode-free pouch cell with a high cathode loading of 6 mAh cm⁻².