A high-energy-density and low-waste battery for energy source transition from C-, H-, and O-based material era to H-...

The discovery of an ideal energy source is always a dream for humans since ancient times. Wood, coal, petroleum and natural gas have played an important role as energy sources in the long history of humans, even at present. However, they are C-, H-, and O-based energy sources, which cause the emission of greenhouse gas CO₂. Therefore, the whole world is always searching for a low-emission or zero-emission energy source. Currently, hydrogen and battery technologies are the two key energy solutions for CO₂ emission reduction. Hydrogen technology can use water as a raw material to produce H₂, which seems to be an ideal solution for low- or zero-emission. However, hydrogen technology has the drawback of low energy conversion efficiency, as well as hydrogen storage and transportation issues. Current battery technology including Li-ion batteries and Na-ion batteries suffers from the disadvantages of battery waste, low safety, low charge speed, and high costs. In this work, in order to overcome the disadvantages of hydrogen and battery technologies, we developed a high-energy-density super flow battery powered by hydrogen peroxide, a kind of zero-emission and low-waste H- and O-based energy source, for energy storage and supply. Unlike conventional one-stage redox flow batteries, the super flow battery has two stages to improve its energy density. We utilized hydrogen peroxide as a catholyte regeneration agent in the second-stage tank of the super flow battery to significantly increase its energy density. We found that the energy density of hydrogen peroxide catholyte regeneration agents and Na₂S anolyte materials reached 305 Wh kg^-1 and 421 Wh kg^-1, respectively, using the two-stage structure of the super flow battery, which endowed the super flow battery with a higher energy density than that of the Li-ion and conventional flow batteries.