Construction of high-performance ZnO/C/Bi<sub>2</sub>O<sub>3</sub> composites and their application in NiZn battery

Abstract

<p indent="0mm">The zinc anode easily encounters some problems such as dendrite growth, shape change, and hydrogen evolution during the charge-discharge process, which lead to the poor cycle life of NiZn battery. To solve these problems, a novel method for surface modification of ZnO was proposed. By using PVA as carbon source, ZnO/C composite was first synthesized; and then, ZnO/C/NH₄Bi₃F₁₀ composite was prepared in the ethylene glycol; ZnO/C/ NH₄Bi₃F₁₀ finally transformed into ZnO/C/Bi₂O₃ after being calcined at high temperature. X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM) and elemental distribution mapping results confirmed the successful synthesis of ZnO/C/Bi₂O₃ composites. The formation mechanism of the composites was discussed in detail. Cyclic voltammetry (CV), electrochemical impedance spectrosocopy (EIS) and constant current charge-discharge tests showed that ZnO/C/Bi₂O₃ composite with the Bi₂O₃ content of 2% displayed the highest electrochemical activity. Furthermore, the NiZn battery assembled from the composite with 2 wt% Bi₂O₃ displayed a cycle life up to 1806 times with the highest energy density of 166.5 Wh kg⁻¹. The energy density of 164.44 Wh kg⁻¹ and Coulombic efficiency of 90% were still maintained after 1806 cycles. The as-prepared ZnO/C/Bi₂O₃ composites exhibit excellent electrochemical performance and great potential for practical applications. This innovative synthesis method is hopeful to be extended to prepare other composites.