Data sets were obtained from GCPL, CV, ICP-OES, XRD, Raman spectroscopy, TEM, STEM-EDX, EELS for the publication.

Abstract: The development of competitive rechargeable Mg batteries is hindered by the poor mobility of divalent Mg ions in cathode host materials. In this work, we have explored a novel dual cation co-intercalation strategy to mitigate the sluggishness of Mg2+ in model TiS2 material. The strategy involved pairing Mg2+ with Li+ or Na+ in dual-salt electrolytes in order to exploit their faster mobility with the aim to reach better electrochemical performance. A combination of experiments and theoretical calculations detailed the charge storage and redox mechanism of co-intercalating cationic charge carriers. Comparative evaluation revealed that the redox activity of Mg2+ can be improved significantly with the help of the dual cation co-intercalation strategy, although the ionic radius of the accompanying monovalent ion plays a critical role on the viability of the strategy. More specifically, a significantly higher Mg2+ quantity was intercalated with Li+ than with Na+ in TiS2. The reason being the absence of phase transition in the former case, which enabled improved Mg2+ storage. Our results highlight the dual cation co-intercalation strategy as an alternative approach to improve the electrochemical performance of rechargeable Mg batteries by opening the pathway to a rich playground of advanced cathode materials for multivalent battery applications.