Hybrid Redox Chemistry in Defective Titanium Polyanion Nanobelt Cathodes for Advanced Magnesium–Ion Batteries
Jianbiao Wang, Xian Yi Tan, Man‐Fai Ng, Gang Wu, Gaoliang Yang, Tanmay Ghosh, Carina Yi Jing Lim, Wutthikrai Busayaporn, Wanwisa Limphirat, Dechmongkhon Kaewsuwan, Deviprasath Chinnadurai, Zhenxiang Xing, Hongfei Liu, Yi Ren, Qingyu Yan, Zhi Wei Seh
Abstract
Abstract Parasitic reactions have hampered transition metal chalcogenide cathodes in magnesium−ion batteries (MIBs), especially for conversion−type cathodes. To fully harness its high theoretical capacity and restrict undesirable side reactions, a defective titanium polyanion cathode ( V s −TiS 3 ) with exposed (001) facets is prepared via a fast−quenching treatment. The performance of the cathode material is investigated in MIBs for the first time, demonstrating a new hybrid energy storage mechanism involving both insertion and conversion reactions. Moreover, the defective TiS 2 formed during cycling is found to have a strong adsorption effect on the side products of magnesium polysulfides (MgS x ), boosting magnesium storage performance. Consequently, the electrodes delivered a substantial capacity of 717.3 mAh g −1 at 25 mA g −1 , and a high capacity of 291.5 mAh g −1 at 500 mA g −1 after 100 cycles, surpassing the performance of previously reported MIBs at the same current density. When employed in pouch cells, a high energy density of 220 Wh kg −1 is achieved. Lastly, this cathode material is also adapted for other mono/multivalent metal−ion batteries (e.g., Li + , Na + , Al 3+ ), demonstrating its versatility.