High dielectric barium titanate porous scaffold for efficient Li metal cycling in anode-free cells

Abstract

Li metal batteries are being intensively investigated as a means to achieve higher energy density when compared with standard Li-ion batteries. However, the formation of dendritic and mossy Li metal microstructures at the negative electrode during stripping/plating cycles causes electrolyte decomposition and the formation of electronically disconnected Li metal particles. Here we investigate the use of a Cu current collector coated with a high dielectric BaTiO₃ porous scaffold to suppress the electrical field gradients that cause morphological inhomogeneities during Li metal stripping/plating. Applying operando solid-state nuclear magnetic resonance measurements, we demonstrate that the high dielectric BaTiO₃ porous scaffold promotes dense Li deposition, improves the average plating/stripping efficiency and extends the cycling life of the cell compared to both bare Cu and to a low dielectric scaffold material (i.e., Al₂O₃). We report electrochemical tests in full anode-free coin cells using a LiNi_0.8Co_0.1Mn_0.1O₂-based positive electrode and a LiPF₆-based electrolyte to demonstrate the cycling efficiency of the BaTiO₃-coated Cu electrode.