Crossover Effects in Batteries with High‐Nickel Cathodes and Lithium‐Metal Anodes

Abstract It is well understood that cathode‐to‐anode crossover, especially of transition‐metal ions, can significantly impact the long‐term cycling of lithium‐ion batteries. The dissolved transition‐metal ions in lithium‐ion cells deposit on the graphite anode, disrupt the solid‐electrolyte interphase (SEI), and catalyze further side reactions. Meanwhile, crossover effects in lithium‐metal batteries have rarely been studied. This study is the first to investigate crossover effects in lithium‐metal batteries with high‐nickel layered‐oxide cathodes. It is shown that the crossover of transition‐metal ions from LiNi 0.9 Mn 0.05 Co 0.05 O 2 has minimal effect on the lithium‐metal anode (LMA) due to the following reasons. The catalytic transition metals 1) have less effect on an inherently reactive LMA, 2) are diluted in a thicker SEI, and 3) are produced in overall lower quantity due to the limited cycle life of the LMA. Conversely, the LMA generates soluble decomposition products that cross over to the cathode even during early cycling. This crossover accelerates impedance growth and capacity fade at the cathode and is partially responsible for the mismatch between the performance of half and full‐cells with layered‐oxide cathodes. This study highlights the need for better battery design with LMA, potentially including electrolyte or cell modifications.