Boosted Li+ transference number enabled via interfacial engineering for dendrite-free lithium metal anodes

Abstract

Adverse dendritic growth destabilizes Li metal anodes (LMAs), dramatically limiting the commercial applications of Li metal batteries (LMBs). Herein, ZIF-67 with unsaturated coordinative metal sites is used to construct a protective coating to immobilize anions, which is capable of increasing the Li⁺ transference number (t_Li⁺) to mitigate the electrolyte concentration gradient in the vicinity of LMAs. In addition, the ZIF-67-based layer provides highly ordered ionic diffusion pathways, thus enabling dendrite-free Li deposition. With a considerable Li⁺ transference number of 0.57, ZIF-67-Cu@Li symmetric cells deliver a superior long-term performance (over 1000 h), and Li–O₂ full batteries with ZIF-67-Cu@Li electrodes display a high energy density of 1911.61 W h kg⁻¹.