Crossover effects of transition metal ions in high-voltage lithium metal batteries

Enhancing the cut-off voltage of high-nickel layered oxide cathodes is an efficient way to obtain higher energy density of lithium-metal batteries (LMBs). However, the phase transition of the cathode materials and the uncontrolled decomposition of the electrolytes at high voltage can lead to irreversible dissolution of transition metal ions, which might cause the crossover effects on the lithium metal anodes. Nonetheless, the mechanism and electrolyte dependence of the crossover effects for Li metal anodes are still unclear. Herein, we investigate the crossover effects between LiNi_0.8Mn_0.1Co_0.1O₂ and Li-metal anode in two electrolyte systems. For ether-based electrolyte, its poor oxidation stability results in massive dissolution of transition metal ions, leading to dendrite growth on anode and rapid cells failure. Conversely, ester-based electrolyte exhibits good electrochemical performances at 4.5 V with little crossover effect. This study provides an idea for electrolyte systems selection for high-voltage LMBs, and verifies that the crossover effect should not be neglected in LMBs.