Proton-Dominated Reversible Aqueous Zinc Batteries with an Ultraflat Long Discharge Plateau

Aqueous zinc batteries (AZBs) are considered promising candidates for large-scale energy storage systems because of their low cost and high safety. However, currently developed AZB cathodes always suffer from the intense charge repulsion of multivalent-ion and complex multiphase electrochemistry, resulting in an insufficient cycling life and impracticable high-sloping discharge profile. Herein, we found that the synthesized ultrathin Bi2O2Se nanosheets can effectively activate stable protons storage in AZBs rather than large zinc ions. This proton-dominated cathode provides an ultraflat discharge plateau (72% capacity proportion) and exhibits long-term cyclability as 90.64% capacity retention after 2300 cycles at 1 A g(-1). Further in situ synchrotron X-ray diffraction, ex situ X-ray photoelectronic spectroscopy, and density functional theory confirm the energy storage mechanism regarding the highly reversible proton insertion/extraction process. Benefiting from the proton-dominated fast dynamics, reliable energy supply (>81.5% discharge plateau capacity proportion) is demonstrated at a high rate of up to 10 A g(-1) and in the frozen electrolyte below -15 degrees C. This work provides a potential design of high-performance electrode materials for AZBs.

Automated summary

The study shows that using ultrathin Bi2O2Se nanosheets as the cathode for AZBs can effectively activate stable proton storage, improving cycling life and discharge characteristics. The cathode demonstrates reliable energy supply capability at high rates and in low-temperature environments.