A single-ion-conducting lithium-based montmorillonite interfacial layer for stable lithium–metal batteries

Abstract

Constructing a robust interfacial layer on lithium metal anodes (LMAs) to inhibit dendrite growth is vital in the pursuit of high-energy density lithium metal batteries (LMBs). Here, lithium-based montmorillonite (Li-MMT) is fabricated as an artificial protective layer to suppress dendritic Li deposition. The Li-MMT layer can not only act as a Li⁺ ion reservoir but also as a single Li⁺ ion conductor, enhancing Li⁺ ion transport kinetics and alleviating the interfacial Li⁺ ion concentration gradient. Theoretical calculations confirm that Li-MMT can immobilize TFSI⁻ ions and allow fast Li⁺ ion shuttle with a low migration energy barrier of 0.28 eV. Finite element method (FEM) simulations further demonstrate the effective modulation of the Li-MMT layer for Li plating behavior, leading to a high Li⁺ transference number (t_Li⁺) of 0.85, a favorable ionic conductivity (σ_Li⁺) of 5.77 × 10⁻⁴ S cm⁻¹ and an extended Li plating/stripping stability over 1300 h. Consequently, excellent cycling performance (206 cycles) with remarkably improved energy density is realized for lithium–oxygen (Li–O₂) full batteries based on Li-MMT–Cu@Li electrodes.