A novel two-dimensional whorled CrB4 and MoB4 as high-performance anode material for metal ion batteries

Abstract

Finding high-storage-capacity anode materials has been a focus of ion-battery research. Two-dimensional (2D) materials have shown promise as high-performance electrode-materials as they have developed gradually. Here we examined the viability of 2D CrB4 and MoB4 monolayers as optimal anode-materials for Li/Na/K ion batteries using first-principles DFT calculations. Preliminary investigations showed that both materials exhibited thermodynamic, structural, and mechanical stability. We found thata strongly negative adsorption energy can help instabilizingthe adsorption of metal-ions on materials surface instead of clustering, that ensures metal-ion-batteries stability. The maximum theoretical storage capacities of Li, Na, and K ions adsorbed on the CrB4 monolayer surface were 1689,1126 and 750 mA h g−1, respectively, while those on the surface of MoB4 were 1155,770 and 513 mA h g−1, respectively. Additionally, calculated open-circuit voltages for Li-ions (0.84,0.82 V), Na-ions (0.25,0.32 V), and K-ions (0.85,0.81 V) for CrB4 and MoB4 monolayers, respectively. Electronic properties showed that increasing the metal ions concentration enhanced both materials’ electrical conductivity and remained the metallic in nature after adsorption. However, Li/Na/K energy barriers are nevertheless consistent with various typical 2D anode materials. The light shaded on 2D MoB4 and CrB4 is anticipated to identify new anode materials for LIBs, NIBs, and KIBs.