Inverse-opal structured TiO2 regulating electrodeposition behavior to enable stable lithium metal electrodes

Abstract

Lithium metal anode is almost the ultimate choice for high-energy density rechargeable batteries, but its uneven electrochemical dissolution-deposition characteristics lead to poor cycle stability and lithium dendrites safety problems. The fundamental solution to the problems is to interfere electrodeposition process of lithium metal so that it can be carried out reversibly and stably. In this work, an inverse-opal structured TiO2 membrane with a thickness of only ∼1 μm is designed to regulate the electrodeposition behavior of lithium metal, in which the ordered channels homogenize mass transfer process, the anatase TiO2 walls of the ion channels reduce desolvation barrier of solvated lithium-ions, and the spherical cavities with a diameter of ∼300 nm confine migration of the adsorbed lithium atoms during electrocrystallization to diminish overpotential of lithium. These systematic effects cover and essentially change the whole process of electrodeposition of lithium metal and eliminate the possibility of lithium dendrite formation. The as-obtained lithium metal electrode delivers a Coulombic efficiency of 99.86% in the 100th cycle, and maintains a low deposition overpotential of 0.01 V for 800 h.

Keywords

• Lithium metal anode
• Inverse-opal structure
• TiO2
• Electrodeposition
• Lithium-sulfur battery