Stress-enhanced lithiation in MAX compounds for battery applications

Abstract

Li-ion batteries are well-established energy storage systems. Upon lithiation conventional group IVA compound anodes undergo large volume expansion and thus suffer from stress-induced performance degradation. Instead of the emerging MXene anodes fabricated by an expensive and difficult-to-control etching technique, we study the feasibility of utilizing the parent MAX compounds. We reveal that M2AC (M=Ti, V and A=Si, S) compounds repel lithiation at ambient conditions, while structural stress turns out to support lithiation, in contrast to group IVA compounds. For V2SC the Li diffusion barrier is found to be lower than reported for group IVA compound anodes, reflecting potential to achieve fast charge/discharge.