CuS2 sheets: a hidden anode material with a high capacity for sodium-ion batteries

Abstract

Due to their low cost and improved safety compared to lithium-ion batteries, sodium-ion batteries have attracted worldwide attention in recent decades. In this work, a hitherto unknown two-dimensional phase of copper disulfide (α-CuS₂) is proposed. First-principles calculations reveal that the proposed monolayer is both statically and dynamically stable. The calculated Na storage capacity reaches up to 841 mA h g⁻¹ and the diffusion energy barrier is only 0.2 eV. Furthermore, we propose a plausible massive synthesis route, which is through mechanical or chemical exfoliation from its bulk counterpart. Our results indicate that the proposed α-CuS₂ monolayer is a promising anode material for sodium-ion batteries.