fig8

Figure 8. (A) Co-intercalation of Zn²⁺ and H⁺ in α-K_0.19MnO₂. (B) voltage-time profile at 1 C and (C) corresponding XRD patterns (ex situ) of α-K_0.19MnO₂ during second discharge/charge cycle. The electrolyte contains Zn(CF₃SO₃)₂ (3 M) and Mn(CF₃SO₃)₂ (0.2 M). Reproduced with permission^[121]. Copyright 2019, Royal Society of Chemistry. (D) GCD profile and corresponding XRD patterns (ex situ) of β-MnO₂ at 0.05 C, suggesting the insertion/extraction of H⁺. (E) TEM/HRTEM observations of β-MnO₂ nanofiber and schematic crystal structure (hetaerolite). Reproduced with permission^[122]. Copyright 2019, Elsevier. (F) sequential insertion of H⁺ and Zn²⁺ during discharge process. Reproduced with permission^[123]. Copyright 2020, Royal Society of Chemistry. (G) charge storage mechanism of MnO₂ cathode involving dissolution-deposition process. Reproduced with permission^[125]. Copyright 2020, Elsevier.