Coupling Oxygen Vacancies and Heterophase Homostructure Achieving High-Rate-Endurable Aqueous Zinc-Ion Storage

Abstract

In recent years, manganese dioxide cathodes have demonstrated unparalleled benefits in aqueous zinc-ion batteries (AZIBs) and aqueous zinc-ion hybrid capacitors (AZICs) owing to their high discharge voltage (∼1.4 V), abundant resources, nontoxicity, high theoretical specific capacity (308 mAh g–1), and various crystal types (α-/β-/δ-/γ-MnO2). Unfortunately, their intrinsic shortcomings, including low conductivity and poor structural stability, lead to unsatisfactory electrochemical performance (poor rate performance and rapid capacity decay). Herein, a novel manganese dioxide cathode material with oxygen vacancies and a heterophase homostructure was designed and produced by a one-step hydrothermal process. This unique design could enhance conductivity and accelerate electron transfer. As expected, AZIBs showed excellent cycle performance with a capacity decay rate of 0.014% per cycle during 2800 cycles as well as outstanding rate performance (76.6 mAh g–1 at 10 A g–1). Furthermore, AZICs offer an energy density of 48.8 Wh kg–1 at a power density of 100 W kg–1 and a capacity retention rate of up to 73.4% even after 10,000 cycles. These discoveries pave the way for the rational design of high-performance electrode materials and provide an innovative option for next-generation energy storage systems.