In order to alleviate the shortage of resources and environmental pollution caused by the extensive use of fossil energy, various countries are accelerating the utilization of renewable energy such as solar energy, wind energy, water conservancy, and tidal energy. However, renewable energy has obvious intermittent characteristics, and it is necessary to develop low-cost, high-efficiency energy storage technology to cooperate with it.
The widely used lithium-ion battery is an excellent electrochemical energy storage technology, but the reserves of lithium resources are very limited and the distribution is extremely uneven, resulting in high cost of lithium-ion batteries and difficulty in recycling, which limits its large-scale application. Wide range of applications in the field of energy storage. The development of new electrochemical energy storage devices based on low cost and easy recycling has important research value and application prospects.
Scientists have developed a new type of high-efficiency and low-cost hybrid supercapacitor based on +2-valent zinc ions as active carriers. The device integrates an inexpensive zinc foil design, and uses it as a negative electrode active material and current collector. The environmentally friendly biomass activated carbon is used as the positive electrode, and the organic solvent dissolved with zinc salt is used as the electrolyte. Through the reduction of zinc ions at the negative electrode /oxidation reaction and adsorption/desorption reaction of anions at the positive electrode to realize the reversible charge and discharge of the capacitor. Zinc is abundant in reserves, and the ion is +2, which enables the hybrid supercapacitor based on zinc ions to obtain high energy density while maintaining the advantages of low cost and easy recovery. After system optimization, this zinc-ion hybrid supercapacitor achieved excellent electrochemical performance: the energy density was higher than 52Wh/kg at a power density of 1725W/kg; and the capacity retention rate was higher than 91% after 22,000 cycles. Large-scale energy storage in the field of renewable clean energy has good application prospects.