Abstract
The rapid increase of intermittent renewable energy such as wind and solar powers requires large-scale, efficient, economic, and zero-emission systems for energy storage.1,2 Energy storage based on the H2-water cycle realized by water electrolyzers and fuel cells has been proposed for large-scale energy storage and grid-balancing.1,3,4 However, the energy efficiency of H2-water cycle is restricted by the sluggish kinetics of the electrochemical oxygen evolution and oxygen reduction reactions in water electrolyzers and fuel cells, respectively.5-7
In this presentation, we will discuss the concept of distributed generation and energy storage systems based on the highly efficient electrochemical cycle of hydrogen peroxide (H2O2).8 In this concept, H2O2 can be electrolyzed to H2 and O2 to store the energy in the short term and then be regenerated via the two-electron oxygen reduction reaction in a fuel cell-type device to generate power. We will also discuss the techno-economical analysis of large-scale, long-term hydrogen and energy storage using H2O2 as the storage media.
As a proof of concept, we will summarize our work on proton exchange membrane hydrogen peroxide electrolyzer (PEM-HPEL), which employs platinum group metal-free (PGM-free) catalysts for hydrogen peroxide oxidation reaction at the anode.8 The prototypes of PEM HPEL showed low onset cell voltage of ca. 0.7 to 0.8 V with 0 to 0.1 V overpotentials and a high voltage efficiency of over 90%. We will also present our work on unitized regenerative hydrogen peroxide cycle cells (UR-HPCC) based on PGM-free bifunctional oxygen electrode catalyst.9 This UR-HPCC operates in either HPEL mode or fuel cell mode for energy storage and power generation, with an ultralow overpotential and an extremely high round-trip voltage efficiency of over 90%. The minimal system cost, low power consumption, and high energy efficiency render the above H2O2 electrochemical cycle systems highly attractive for short- and long-term energy/hydrogen storage.
References
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Acknowledgements
Financial support from the State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences is greatly appreciated. This study was financially supported by the autonomous research project of SKLCC (Grant No. 2021BWZ006), ICC CAS (Grant No. 2020SC001), Key Research and Development (R&D) Projects of Shanxi Province (Grant No. 202102070301018) and Shanxi Province grant (Grant No. 20210302123011 and 202103021224442).