Construction of self-sacrificing selenium interfacial coating and its performance in all-solid-state lithium-ion batteries

Abstract

All-solid-state lithium-ion batteries (ASSLIBs) are considered a crucial direction for the development of next-generation energy technologies, owing to their high energy density and superior safety performance. However, the incompatibility between high-voltage cathode materials, such as LiCoO2 (LCO), and sulfide solid electrolytes (sulfide SEs) presents a bottleneck that limits overall performance. To address this issue, we have proposed an in situ selenium-induced thermal reduction strategy to form a selenium-containing interfacial layer. Within this layer, Co (III) from LCO is reduced to the less oxidative Co (II), effectively suppressing the parasitic reactions between LCO and sulfide SEs. Employing this interface engineering approach, the Se-LCO/ Li6PS5Cl /Li-In ASSLIB cell achieves a high initial specific capacity of 157.2 mAh g−1 at 0.2 C, significantly enhanced Li+ diffusivity with a DLi of 10−9 cm2 s−1 (approximately one order of magnitude higher than the original sample), and excellent cycling stability with a capacity retention of 90.1% after 100 cycles at 0.5 C. The experimental results confirm the effectiveness of the selenium coating strategy in enhancing interface compatibility and optimising electrochemical cycling performance. This study introduces a self-sacrificing in situ coating method for selenium-reduced cathode materials, offering innovative insights into the design of high-performance ASSLIBs with stable cathode/sulfide SEs interfaces.