A Dynamic, Electrolyte-Blocking, and Single-Ion-Conductive Network for Stable Lithium-Metal Anodes

Summary

Implementation of lithium (Li)-metal anodes requires developments to solve the heterogeneity and instability issues of naturally formed solid-electrolyte interphase (SEI). The artificial SEI, as an alternative, enables an ideal interface by regulating critical features such as fast ion transport, conformal protection, and parasitic reaction mitigation. Herein, for the first time, we integrate all of these desired properties into a single matrix, the dynamic single-ion-conductive network (DSN), as a multifunctional artificial SEI. The DSN incorporates the tetrahedral Al(OR)₄⁻ (R = soft fluorinated linker) centers as both dynamic bonding motifs and counter anions, endowing it with flowability and Li⁺ single-ion conductivity. Simultaneously, the fluorinated linkers provide chain mobility and electrolyte-blocking capability. A solution-processed DSN coating was found to simultaneously hinder electrolyte penetration, mitigate side reactions between Li and electrolyte, maintain low interfacial impedance, and allow homogenous Li deposition. With this coating, long cycle life and high Coulombic efficiency are achieved for Li-metal battery in a commercial carbonate electrolyte.