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Ultraporous, Ultrasmall MgMn 2 O 4 Spinel Cathode for a Room-Temperature Magnesium Rechargeable Battery

2023; American Chemical Society; Volume: 17; Issue: 3 Linguagem: Inglês

10.1021/acsnano.2c12392

1936-086X

Hiroaki Kobayashi, Yu Fukumi, Hiroto Watanabe, Reona Iimura, Naomi Nishimura, Toshihiko Mandai, Yoichi Tominaga, Masanobu Nakayama, Tetsu Ichitsubo, Itaru Honma, Hiroaki Imai,

MXene and MAX Phase Materials

Magnesium rechargeable batteries (MRBs) promise to be the next post lithium-ion batteries that can help meet the increasing demand for high-energy, cost-effective, high-safety energy storage devices. Early prototype MRBs that use molybdenum-sulfide cathodes have low terminal voltages, requiring the development of oxide-based cathodes capable of overcoming the sulfide's low Mg2+ conductivity. Here, we fabricate an ultraporous (>500 m2 g–1) and ultrasmall (<2.5 nm) cubic spinel MgMn2O4 (MMO) by a freeze-dry assisted room-temperature alcohol reduction process. While the as-fabricated MMO exhibits a discharge capacity of 160 mAh g–1, the removal of its surface hydroxy groups by heat-treatment activates it without structural change, improving its discharge capacity to 270 mAh g–1─the theoretical capacity at room temperature. These results are made possible by the ultraporous, ultrasmall particles that stabilize the metastable cubic spinel phase, promoting both the Mg2+ insertion/deintercalation in the MMO and the reversible transformation between the cubic spinel and cubic rock-salt phases.