A potential large-scale energy conversion/storage system: an aqueous rechargeable battery with intercalated potassium compound.

Here, we report the rechargeable aqueous battery of Zn/K_0.17MnO₂ with multiple metal ions in the electrolyte based on K_0.17MnO₂ as the cathode and zinc as the anode. The microspheres of broccoli-like K_0.17MnO₂ made up of large rod particles with a size of about 200 nm in diameter are synthesized by hydrothermal method followed by calcination at 500 °C in air for 2 h. The cyclic voltammetry measurement demonstrates that it is easy to intercalate into the cathode for zinc ions with smaller radius compared with potassium ions. The galvanostatic charge/discharge test displays that it delivers the initial discharge capacity of 189.3 mAh g⁻¹ at 100 mA g⁻¹ after adding 0.05 mol L⁻¹ MnSO₄ into the hybrid electrolyte. Meanwhile, the discharge capacity retains still up to 78.4 mAh g⁻¹ at a current density of 3200 mA g⁻¹, indicating the much better cycle stability than that without additive and the superfast ion transport characteristic. [ABSTRACT FROM AUTHOR]