Electrochemical synthesis of Na_0.25MnO₂@ACC cathode and Zn@K-ACC anode for flexible quasi-solid-state zinc-ion battery with superior performance

Flexible rechargeable zinc-ion batteries (FRZIBs) are considered to be a promising candidate for energy storage devices owing to their safety, environmental benignity and material abundant. However, the FRZIBs suffer from low operating voltage, low energy density and poor flexibility, limiting their further large-scale applications. Herein, a facile electrochemical method is employed to prepare Na_0.25MnO₂@activated carbon cloth (Na_0.25MnO₂@ACC) cathode and Zn@K⁺-inserted activated carbon cloth (Zn@K-ACC) anode for zinc-ion battery. Benefiting from the phase evolution from Mn₃O₄ to Na_0.25MnO₂ by simultaneous Na⁺ insertion and MnO₂ conversion during electrochemical treatment, the potential range for Na_0.25MnO₂@ACC cathode can be extended to 0–1.3 V with significantly increased capacity up to 292.36 mAh g⁻¹. Analogously, flexible Zn@K-ACC anode with high electrochemical performance can also be prepared by pre-inserting K⁺. The Na_0.25MnO₂@ACC//Zn@K-ACC battery delivers a high-operating voltage plateau of 1.60 V and a large energy density of 504.49 Wh kg⁻¹ at a power density of 1.54 kW kg⁻¹ as well as an excellent cyclic stability over 2000 cycles with 91.8% capacity retention at a current density of 2.0 A g⁻¹. Impressively, the capacity changes slightly under mechanical bending, and the capacity has only 7.2% loss after 1000 bending cycles.