Spinel Li4Mn5O12 as 2.0 V Insertion Materials for Mg-Based Hybrid Ion Batteries

Graphical High energy density : A spinel Li 4 Mn 5 O 12 cathode material with unique nano-/microspheres is prepared by using a low-temperature method. As a cathode for 2 V hybrid Mg−Li batteries, Li 4 Mn 5 O 12 exhibits a reversible specific capacity of 155 mAh g −1 and a long discharge voltage platform exceeding 2.0 V (vs. Mg/Mg 2+ ) coupled with a high energy density of 326 Wh kg −1 at a current density of 0.1 C (1 C=163 mA g −1 ). With the increasing demand for electrical energy storage, a new Mg−Li hybrid battery with Mg anode is regarded as a promising candidate because of low cost, high volumetric capacity, and dendrite-free nature of the Mg anode. Nevertheless, the characteristics of low operation voltage and low energy density for Mg−Li hybrid batteries hinders their widespread application, owing to limited reversible cathodes. To overcome these issues, a highly reversible fast Li + insertion cathode with high voltage is an effective strategy to realize high-energy-density Mg−Li hybrid batteries. Herein, we develop the 2 V high-voltage spinel Li 4 Mn 5 O 12 cathode material with unique nano-/microspheres, using a novel low-temperature method, offering a short Li-diffusion path and sufficient transport channels for electrolyte penetration into the electrode. For the first time, we demonstrate the feasibility of the spinel Li 4 Mn 5 O 12 nano-/microspheres with hierarchical architecture as a cathode for 2 V hybrid Mg−Li batteries. It exhibits a reversible specific capacity of 155 mAh g −1 and a long discharge voltage platform exceeding 2.0 V (vs. Mg / Mg 2+ ) coupled with high energy density of 326 Wh kg −1 at a current density of 0.1 C (1 C=163 mA g −1 ). Our results pave the way of constructing new hybrid Mg−Li batteries with high voltage and high energy density.