Abstract
The intercalation compounds are generally considered as ideal electrode materials for lithium-ion
batteries thanks to their minimum volume expansion and fast lithium ion diffusion. However, cracking still occurs in those compounds and has been identified as one of the critical issues responsible for their capacity decay and short cycle life, although the diffusion-induced stress and volume expansion are much smaller than those in alloying-type electrodes. Here, we designed a thin-film model system that enables us to tailor the cation ordering in LiNi0.5Mn1.5O4 spinels and correlate the stress patterns, phase evolution, and cycle performances. Surprisingly, we found that distinct reaction paths cause negligible difference in the overall stress patterns but significantly
different cracking behaviors and cycling performances: 95% capacity retention for disordered LiNi0.5Mn1.5O4 and 48% capacity retention for ordered LiNi0.5Mn1.5O4 after
2000 cycles. We were able to pinpoint that the extended solid-solution region with suppressed phase transformation attributed to the superior electrochemical performance of disordered spinel. This work envisions a strategy for rationally designing stable cathodes for lithium-ion
batteries through engineering the atomic structure that extends the solid-solution region and suppresses phase transformation.
