Molybdenum Dichalcogenide Cathodes for Aluminum-Ion Batteries

Many successful battery electrodes are based on 2D-layered materials. Aluminum-ion batteries are studied using molybdenum dichalcogenides: MoS₂, MoSe₂, and MoSSe as active cathode materials. The batteries show clear discharge voltage plateaus in the ranges 1.6–1.4 V for MoS₂ and MoSe₂, and 0.6–0.5 V for MoSSe. MoS₂ and MoSe₂ have similar crystal structures; interestingly, it is found that MoSe₂ performed better than MoS₂. MoSSe exhibits a higher specific capacity over MoS₂ and MoSe₂, but the energy density is lower than MoSe₂ at a current rate of 40 mA g⁻¹. MoSe₂ cells record a discharge capacity of ≈110 mAh g⁻¹ with an average potential in the range of 2.0–1.8 V and 1.5–0.8 V during discharge. The cells are stable at 100 mA g⁻¹ for over 200 cycles with 90% coulombic efficiency.