Boosting the Cycling Stability of Aqueous Flexible Zn Batteries via F Doping in Nickel–Cobalt Carbonate Hydroxide Cathode

Abstract

Cathodes of rechargeable Zn batteries typically face the issues of irreversible phase transformation, structure collapse, and volume expansion during repeated charge/discharge cycles, which result in an increased transfer resistance and poor long-term cycling stability. Herein, a facile F doping strategy is developed to boost the cycling stability of nickel cobalt carbonate hydroxide (NiCo–CH) cathode. Benefiting from the extremely high electronegativity, the phase and morphology stabilities as well as the electrical conductivity of NiCo–CH are remarkably enhanced by F incorporation (NiCo–CH–F). Phase interface and amorphous microdomains are also introduced, which are favorable for the electrochemical performance of cathode. Benefiting from these features, NiCo–CH–F delivers a high capacity (245 mA h g⁻¹), excellent rate capability (64% retention at 8 A g⁻¹), and outstanding cycling stability (maintains 90% after 10 000 cycles). Moreover, the quasi-solid-state battery also manifests superior cycling stability (maintains 90% after 7200 cycles) and desirable flexibility. This work offers a general strategy to boost the cycling stability of cathode materials for aqueous Zn batteries.