fig3

Figure 3. Hydrogen evolution in the aqueous ZIBs. (A) In-situ optical microscope observing the formation of bubbles at the anode surface. (B) Generation of H₂ gas under different charge-discharge states, demonstrated by DEMS^[47]. Copyright 2019 Elsevier B.V. (C) Illustration of in-situ GC measurement by connecting the pouch cell and the GC equipment. (D) H₂ generation detected by GC at different cycles in different electrolytes^[48]. Copyright 2023 John Wiley & Sons. (E) In-situ gas pressure detection for the batteries, with the evolution of gas generation converted to the amount of H₂ using the ideal gas equation^[49]. Copyright 2022 The Royal Society of Chemistry. (F) Evolution of pH at different charge-discharge states. (G) X-ray diffraction (XRD) measurements demonstrating the generation of surface passivation of Zn anode in ZnSO₄ electrolyte after cycling^[50]. Copyright 2022 John Wiley & Sons.