Layered buserite Mg-Mn oxide cathode for aqueous rechargeable Mg-ion battery

Owing to the features (high safety, inexpensive and environmental friendliness) of aqueous rechargeable Mg-ion batteries (ARMIBs), they have drawn extensive attention in the future energy storage systems. However, the poor Mg2+ migration kinetics during the Mg2+ intercalation/extraction still hinders the progress of developing suitable cathode materials. Herein, a layered buserite Mg-Mn oxide (MMO) material with large interlayer space (∼9.70 Å) and low-crystalline structure is studied as a high-performance cathode in ARMIBs. Compared with the counterpart, the Mg2+ migration kinetics of the MMO cathode can be enhanced by its unique structure (bigger interlayer spacing and low-crystalline structure). The layered buserite MMO as a high-performance ARMIBs cathode exhibits high Mg storage capacity (50 mA g−1: 169.3 mAh g−1), excellent rate capability (1000 mA g−1: 98.3 mAh g−1), and fast Mg2+ migration (an average diffusion coefficient: ∼4.21 × 10−10 cm2 s−1) in 0.5 M MgCl2 aqueous electrolyte. Moreover, the MMO-1//AC full battery achieved a high discharge capacity (100 mA g−1: 111 mAh g−1), and an ignored fading over 5000 cycles (1000 mA g−1). Therefore, layered Mg-Mn oxide with large interlayer space may break a new path to develop the promising ARMIBs.