Advanced aqueous zinc battery with excellent rate and low-temperature adaptation enabled by bimetallic phosphide with hetero-interface

Abstract

Alkaline aqueous zinc batteries (AAZBs) characterized by high energy density, cost-efficiency and environmental friendliness have been deemed to the most promising candidate for next-generation energy conversion system. However, the pitiable conductivity and stability in traditional cathode materials severely influence the rate-capability, and specific capacity of AAZBs, particularly in low-temperature. Herein, a hierarchical phosphide hetero-structure (NiCoP@Ni2P) as cathode material for AAZBs is constructed by the one-step phosphorization strategy. The charge redistribution at the heterogeneous interface of NiCoP@Ni2P cathode is demonstrated via experiment and theoretical calculation. Thanks to the elaborate hetero-interface, the NiCoP@Ni2P electrode enjoying the favorable ion adsorption energy and fast interfacial diffusion kinetics exhibits a high specific capacity (358.3 mA h g−1 at 1 A g−1) and outstanding rate capability (224.4 mA h g−1 at 20 A g−1). The as-assembled AAZBs coupled with Zn anode present a high energy density of 596.3 Wh kg−1 at the power density of 1.7 kW kg−1, and retains 429.5 Wh kg−1 even at a very high power density of 24.3 kW kg−1 Specifically, this full cell can work well at a low temperature of −30 °C, with an ultra-high specific capacity of 307.9 mA h g−1 at 1 A g−1 and outstanding stability of 85% retention after 2000 cycles at 10 A g−1.