Controlling the intercalation chemistry to design high-performance dual-salt hybrid rechargeable batteries

We have conducted extensive theoretical and experimental investigations to unravel the origin of the electrochemical properties of hybrid Mg²⁺/Li⁺ rechargeable batteries at the atomistic and macroscopic levels. By revealing the thermodynamics of Mg²⁺ and Li⁺ co-insertion into the Mo₆S₈ cathode host using density functional theory calculations, we show that there is a threshold Li⁺ activity for the pristine Mo₆S₈ cathode to prefer lithiation instead of magnesiation. By precisely controlling the insertion chemistry using a dual-salt electrolyte, we have enabled ultrafast discharge of our battery by achieving 93.6% capacity retention at 20 C and 87.5% at 30 C, respectively, at room temperature.