Abstract The combination of Li-rich layered oxide cathodes and lithium metal anodes enables lithium metal batteries (LMBs) to achieve specific energies exceeding 600 Wh kg−1, which is a crucial threshold requiring the activation of anionic oxygen-redox of cathode. The specific energy is attained owing to oxygen-redox reactions at the cathode and reversible Li plating–stripping at the anode, but these processes also induce distinct failure mechanisms.