Combining Quinone‐Based Cathode with an Efficient Borate Electrolyte for High‐Performance Magnesium Batteries

Abstract Rechargeable magnesium batteries are gaining attention as promising candidates for large‐scale energy storage applications because of their potentially high energy, safety and sustainability. However, the development of Mg batteries is impeded by the lack of efficient cathode materials and compatible electrode‐electrolyte combinations. Herein, we demonstrate a new poly(1,4‐anthraquinone)/Ketjenblack composite (14PAQ@KB) in combination with non‐corrosive magnesium tetrakis(hexafluoroisopropyloxy) borate Mg[B(hfip)₄]₂ (hfip=OC(H)(CF₃)₂) electrolyte towards high‐energy and long‐lifespan Mg batteries. This combination exhibits prominent electrochemical performance including a maximum discharge capacity of 242 mA h g⁻¹ (approximately 93 % of the theoretical capacity), superior cycling stability (81 mA h g⁻¹ after 1000 cycles), and excellent rate capability (120 mA h g⁻¹ at 5 C).