Ultraporous, Ultrasmall MgMn<sub>2</sub>O<sub>4</sub> Spinel Cathode for a Room-Temperature Magnesium Rechargeable Battery.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 36669094.
- Also identified by DOI 10.1021/acsnano.2c12392 and PMC identifier 9933879.
- Licence recorded as CC BY-NC-ND.
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Abstract
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 Mg<sup>2+</sup> conductivity. Here, we fabricate an ultraporous (>500 m<sup>2</sup> g<sup>-1</sup>) and ultrasmall (<2.5 nm) cubic spinel MgMn<sub>2</sub>O<sub>4</sub> (MMO) by a freeze-dry assisted room-temperature alcohol reduction process. While the as-fabricated MMO exhibits a discharge capacity of 160 mAh g<sup>-1</sup>, the removal of its surface hydroxy groups by heat-treatment activates it without structural change, improving its discharge capacity to 270 mAh g<sup>-1</sup>─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 Mg<sup>2+</sup> insertion/deintercalation in the MMO and the reversible transformation between the cubic spinel and cubic rock-salt phases.