Enhancing lithium storage performance of bimetallic oxides anode by synergistic effects.

Spinel bimetallic transition metal oxide anode such as ZnMn2O4, has drawn increasing interest due to attractive bimetal interaction and high theoretical capacity. While it suffers from huge volume expansion and poor ionic/electronic conductivity. Nanosizing and carbon modification can alleviate these issues, while the optimal particle size within host is unclear yet. We here propose an in-situ confinement growth strategy to fabricate pomegranate-structured ZnMn2O4 nanocomposite with calculated optimal particle size in mesoporous carbon host. Theoretical calculations reveal favorable interatomic interactions between the metal atoms. By the synergistic effects of structural merits and bimetal interaction, the optimal ZnMn2O4 composite achieves greatly improved cycling stability (811 mAh g-1 at 0.2 A g-1 after 100 cycles), which can maintain its structural integrity upon cycling. X-ray absorption spectroscopy analysis further confirms delithiated Mn species (Mn2O3 but little MnO). Briefly, this strategy brings new opportunity to ZnMn2O4 anode, which could be adopted to other conversion/alloying-type electrodes.