A Magnesium/Lithium Hybrid-Ion Battery with Modified All-Phenyl-Complex-Based Electrolyte Displaying Ultralong Cycle Life and Ultrahigh Energy Density

Magnesium/lithium hybrid-ion batteries (MLHBs) combine the advantages of high safety and fast ionic kinetics, which enable them to be promising emerging energy-storage systems. Here, a high-performance MLHB using a modified all-phenyl complex with a lithium bis(trifluoromethanesulfonyl)imide electrolyte and a NiCo2S4 cathode on a copper current collector is developed. A reversible conversion involving a copper collector with NiCo2S4 efficiently avoids the electrolyte dissociation and diffusion difficulties of Mg2+ ions, enabling low polarization and fast redox, which is verified by X-ray absorption near edge structure analysis. Such combination affords the best MLHB among all those ever reported, with a reversible capacity of 204.7 mAh g(-1) after 2600 cycles at 2.0 A g(-1), and delivers an ultrahigh full electrode-basis energy density of 708 Wh kg(-1). The developed MLHB also achieves good rate performance and temperature tolerance at -10 and 50 degrees C with a low electrolyte consumption. The hybrid-ion battery system presented here could inspire a broad set of engineering potentials for high-safety battery technologies and beyond.

Automated summary

A high-performance magnesium/lithium hybrid-ion battery (MLHB) has been developed in this study, achieving excellent performance in terms of safety, cycle life, and energy density through the use of modified complex, new electrolyte, and special cathode material. This hybrid-ion battery system has significant engineering potentials for advancing high-safety battery technologies and related fields.