This paper compares the oxygen reduction on four MnO2‐based air cathodes assembled in home‐made electrochemical cells, with some particular observations on α‐MnO2 cathode. The results show that the catalytic activity decreases in the following order: electrolytic MnO2 (EMD) > natural MnO2 (NMD) > β‐MnO2 > α‐MnO2. The maximum power density of the zinc‐air battery with EMD as the catalyst reaches up to 141.8 mW cm−2 at the current density of 222.5 mA cm−2, which is about 60%, 20% and 10% higher than that of α‐MnO2 (90.0 mW cm−2 at 120.3 mA cm−2), β‐MnO2 (121.5 mW cm−2 at 150.4 mA cm−2) and NMD (128.2 mW cm−2 at 207.8 mA cm−2), respectively. It is believed that its unique crystal structure and biggest BET surface area make EMD have the smallest charge transfer resistance (Rct), thus EMD has the highest activity.
The development of high-efficiency multi-component composite anode nanomaterials for sodium-ion batteries (SIBs) is critical for advancing the further practical application. Numerous multi-component nanomaterials are constructed typically via confinement strategies of surface templating or three-dimensional encapsulation. Herein, a composite of heterostructural multiple sulfides (MoS2/SnS/CoS) well-dispersed on graphene is prepared as an anode nanomaterial for SIBs, via a distinctive lattice confinement effect of a ternary CoMoSn-layered double-hydroxide (CoMoSn-LDH) precursor. Electrochemical testing demonstrates that the composite delivers a high-reversible capacity (627.6 mA h g−1 after 100 cycles at 0.1 A g−1) and high rate capacity of 304.9 mA h g−1 after 1000 cycles at 5.0 A g−1, outperforming those of the counterparts of single-, bi- and mixed sulfides. Furthermore, the enhancement is elucidated experimentally by the dominant capacitive contribution and low charge-transfer resistance. The precursor-based lattice confinement strategy could be effective for constructing uniform composites as anode nanomaterials for electrochemical energy storage.
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