Magnesium rechargeable #batteries (MRBs) have a great attention as post lithiumion batteries due to meet the increasing demand of high-energy, cost-effective, and highsafety for energy storage devices. The prototype MRBs using sulfide #cathodes operate low terminal voltages, therefore development of oxide-based high-voltage cathodes, having lower Mg2+ conductivity, is promptly required. In Japan, oxide-based MRB cathode materials are developing in JST ALCA-SPRING project. Herein, an ultraporous (larger than 500 m2 g-1) and ultrasmall (Less than 2.5 nm) cubic spinel MnMn2O4 (MMO) is fabricated by freeze-dry assisted room temperature alcohol reduction process. The MMO cathode exhibits the low discharge capacity of 160 mAh g-1, but is activated by eliminating its surface hydroxy groups by heat-treatment without structure change, demonstrating the discharge capacity of 270 mAh g-1, corresponding to its theoretical capacity, at room temperature in the MRB full #cell. The tiny particles stabilize the metastable cubic spinel phase, promoting deep Mg2+ insertion into the MMO and reversible transformation between cubic spinel and cubic rocksalt phases.
1 апр 2023
