Stress-enhanced lithiation in MAX compounds for battery applications

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.