Strong Carbon Layer-Encapsulated Cobalt Tin Sulfide-Based Nanoporous Material as a Bifunctional Electrocatalyst for Zinc-Air Batteries.

Global demands for cost-effective, durable, highly active, and bifunctional catalysts for metal-air batteries are tremendously increasing in scientific research fields. In this work, a strategy for the rational fabrication of carbon layer-encapsulated cobalt tin sulfide nanopores (CoSnOH/S@C NPs) material as a bifunctional electrocatalyst for rechargeable zinc (Zn)-air batteries by a cost-effective and facile two-step hydrothermal method is reported. Moreover, the effect of metal elements on the morphology of CoSnOH nanodisks material via the hydrothermal method is investigated. Owing to its excellent nanostructure, exclusive porous network, and high specific surface area, the optimized CoSnOH/S@C NPs material reveals superior catalytic properties. The as-prepared CoSnOH/S@C NPs electrocatalyst reveals better properties of oxygen reduction reaction (half-wave potential of -0.88 V vs reversible hydrogen electrode) and oxygen evolution reaction (overpotential of 137 mV at 10 mA cm-2) when compared with commercial Pt/C and IrO2 catalyst materials. Most significantly, the CoSnO/S@C NPs-based Zn-air battery exhibits more excellent cycling stability than the Pt/C+IrO2 catalyst-based one. Consequently, the proposed material provides a new route for fabricating more active and stable multifunctional catalyst materials for energy conversion and storage systems.

Oxygenated copper vanadium selenide composite nanostructures as a cathode material for zinc-ion batteries with high stability up to 10 000 cycles.

The development of aqueous zinc-ion batteries (AZiBs) towards practical implementations is hampered by unsuitable host cathode materials. Herein, we reported a high-capacity, stable, and long-cycle-life (10 000 cycles) oxygenated copper vanadium selenide composite material (Cu0.59V2O5/Cu0.828V2O5@Cu1.8Se1/Cu3Se2, denoted as O-CuVSe) as a cathode for AZiBs. The newly constructed O-CuVSe composite cathode can be operated in the wide potential window of 0.4-2.0 V, exhibiting a high specific capacity of 154 mA h g-1 at 0.2 A g-1 over 100 cycles. Interestingly, the O-CuVSe composite cathode delivered excellent specific capacities of 117 and 101.4 mA h g-1 over 1000 cycles at 1 and 2 A g-1, respectively. Even at a high current density of 5 A g-1, the cathode delivered a high reversible capacity of 74.5 mA h g-1 over an ultra-long cycling life of 10 000 cycles with no obvious capacity fading. Apart from this, the cathode exhibited excellent rate capability at different current densities. The superior electrochemical properties originate from the synergistic effects between the oxygen vacancy engineering and interlayer doping of Cu ions to increase the structural stability during the cycling, enhancing the electron/ion transport kinetics. Moreover, the Zn2+ storage mechanism in the Zn/O-CuVSe aqueous rechargeable battery was explored. This study provides a new opportunity for the fabrication of different kinds of a new class of cathode materials for high-voltage and high-capacity AZiBs and other energy storage devices.