Does “zero-strain” lithiated spinel serve as a strain retardant and an irreversible phase transition regulator for layered oxide cathodes?

Abstract

Layered oxide cathodes encounter structural challenges during cycling, prompting the exploration of an ingenious heterostructure strategy, which incorporates stable components into the layered structure as strain regulators to enhance materials cycle stability. Despite considerable research efforts, identifying suitable, convenient, and cost-effective materials and methods remains elusive. Herein, focused on lithium cobalt oxide (LiCoO₂), we utilized its low-temperature polymorph as a strain-retardant embedded within a cathode. Our findings reveal that the low-temperature component, exhibiting zero-strain characteristic, adopts a complex configuration with a predominant lithiated spinel structure, also featuring both cubic-layered and typical-layered configurations. But this composite cathode exhibits a sluggish lithium-ion transport rate, attributed to Co&Li dislocation at the dual structural boundaries and the formation of cobalt(III) oxide. This investigation presents a pioneering endeavor in employing heterostructure strategies, underscoring the critical role of such strategies in component selection, which ultimately propels the advancement of layered oxide cathode candidates for Li-ion battery technology.