Searching for the Ideal Li1+xTMO2 Cathode for Anode-free Li Metal Batteries

Abstract

Anode-free lithium metal batteries push the energy density higher and minimize battery production costs as low as possible. However, the fast capacity decay impedes their commercial viability, primarily due to the lack of excessive Li from the anode to compensate for the irreversible lithium loss. Thus, the Li-rich NCM cathode is a feasible way to solve the issue. In this work, to search for the ideal Li_1+xTMO₂ cathode for anode-free Li metal batteries, we selected the two types of commonly used layered cathode materials (LiTMO₂: NCM622 and NCM811) to enrich Li converting into Li₂TMO₂ by both chemical lithiation (C-Li) and electrochemical lithiation (E-Li) methods. Our findings show that the Li-rich NCM622 lithiated by the E-Li method is an ideal choice among our candidates, which has a high lithiation degree that almost covers the entire reversible transition range from Li₁ to Li₂ without additional by-products and a negative impact on kinetic performance. Based on the above results, we further demonstrated that the Li_1.33NCM622|Cu pouch cell presents a longer cycle life of more than 200 times with a high capacity retention of 74%.