High-rate aqueous zinc-ion batteries enabled by a polymer/graphene composite cathode involving reversible electrolyte anion doping/dedoping

Abstract

It has long been of interest to explore cathode materials for achieving high-performance rechargeable zinc ion batteries through rational design and highly efficient synthesis. Based on the combination of reversible Zn²⁺ insertion/-extraction and electrolyte anion doping/dedoping mechanisms, a polymer/graphene composite cathode, named poly-quinol-phenylenediamine/graphene (POLA/G), is obtained via a hydrothermal synthesis method. The hydroquinone and p-phenylenediamine building blocks of POLA/G can not only provide a reversible redox reaction associated with Zn²⁺, but they can also interact with the anions in the aqueous electrolyte. As a result, Zn//POLA/G batteries deliver extremely good electrochemical performance, with a high-rate capability of 225 mA h g⁻¹ at 0.1 A g⁻¹ and 152 mA h g⁻¹ at 20 A g⁻¹. Moreover, the composite cathode presents exceptional long-term cycling performance, retaining 90% of its initial capacity after 5000 cycles at a current of 10 A g⁻¹. Hence, this work develops a new direction for the use of polymers to increase zinc ion storage.