Multilayered grapheneembedded 2D MoSxSey (x: y=1:3 and 2:1) cathode engineering for high-performance sodium sulfur-selenium hybrid battery

Theoretical density functional theory (DFT) calculations have been done to find out the electronic band structures of the thermodynamically stable composites MoS_xSe_y (x:y = 2:1 and 1:3). The new experimental strategy to synthesize the multilayered graphene-MoS_xSe_y (x: y = 1:3 and 2:1) composites has been successfully developed and the Na₂S_xSe_y nano composites is generated for being used as cathode materials in Na-SSe hybrid battery for its stable performance of generated Na₂S_xSe_y cathode electrode material. The multi-layered graphene (MLGr) structure, which is sandwiched, plays a significant role in the conversion of the internal Na₂S_xSe_y cathode material. This occurs through the electrochemical reduction of the active MLGr-MoS_xSe_y structure at a voltage as low as 0.01 V relative to Na⁺/Na. The stable performance of the battery is enhanced through the incorporation of vinylene carbonate (VC) into the electrolyte, resulting in the spontaneous formation of a stable layer at the electrode-electrolyte interface. The self-supported VC-active MLGr-MoS₂Se₁ material achieves a high reversible capacity of 295 mAh/g after 500 cycles at 1.0 A/g. This process reduces battery swelling and speed up ion movement, boosting rate capability. The better stable cyclic performance has been observed for the active material MLGr-MoS₂Se₁ as compared to the active material MLGr-MoS₁Se₃. The interconnected MLGr structure enhances flexibility and facilitates fast ionic/electronic transport, as confirmed by impedance measurements. This design shows great potential for stable, next -generation Na-S_xSe_y hybrid batteries.