First-principle study of Ti2XS2 (X = C/N) MXenes as high capacity anodes for rechargeable potassium-ion batteries

[Display omitted] •2D sulfurized MXenes (Ti2CS2 and Ti2NS2) are proposed as potassium ion battery anode materials.•Strong adsorption and low diffusion energy barrier of K adatom are received.•Higher theoretical capacity of potassium ion battery than most carbon-based materials. Potassium-ion batteries (KIBs) are potential substitutions of lithium-ion batteries, considering the superiority of K in abundance and safety compared with lithium. Recently, the MXenes emerged as a significant class of two-dimensional materials in energy storage applications. Herein we investigated the performances of two S-functionalized MXenes (S-MXenes), Ti2CS2 and Ti2NS2, as anodes for KIBs through first-principle calculations. The results show that both S-MXenes possess metallic nature and structural integrity. Besides, the two functionalized structures exhibit strong adsorptions and low diffusion energy barriers, suggesting fast charge–discharge rates. By reaching the ultimate structural configurations, the theoretical capacities are as high as 312 mAh/g with low but positive open circuit voltage. All the performances reveal that the S-MXenes are promising anode materials for KIBs and expand their application as electrode materials.