Exploring the potential of out-of-plane MXenes as cathodes for aqueous Al-ion batteries: Ab initio investigation

초록

Aqueous Al-ion batteries (AAIBs) are promising candidates for next-generation energy storage systems due to their high safety and low cost. However, limitations include their instability and low electrical conductivity. MXenes are gaining attention as cathode materials that can potentially address these challenges owing to their excellent conductivity, cycling stability, and high capacity. We investigated out-of-plane MXenes (where M ' and M '' = Sc, Ti, V, Cr, and Mn) using ab initio and ab initio molecular dynamics simulations, assessing their structural and aqueous stability, electronic conductivity, Al adsorption behavior, theoretical capacity and voltage profile. Out-of-plane MXenes, particularly Cr2ScC2O2 and Cr2MnC2O2, exhibited suitable aqueous stability and Al adsorption energies. These MXenes achieved Al storage capacities of 392.256 and 374.040 mAh/g, respectively, surpassing graphite (165 mAh/g) and 2D V2O5 (255 mAh/g). Remarkably, Cr2ScC2O2 showed potential to reach a capacity of 588.384 mAh/g. Both MXenes were stable when interacting with AlCl3 electrolyte, suggesting that they are promising for practical use.

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