Green energy storage: Enhanced stability for rechargeable batteries

Green energy grids will require large scale, rechargeable batteries to store the energy generated by renewable technologies. Now, scientists at King Abdullah University of Science and Technology in Saudi Arabia, alongside researchers in China, have made a considerable leap forward in refining the design of aqueous zinc-ion batteries (ZIBs) for this purpose. 

Electrochemical batteries convert chemical energy into electrical energy, and can be recharged through an opposite process, but energy losses always occur in this cycle, degrading the battery life. Lithium-ion batteries have been among the best storage solutions, but suffer from safety and environmental concerns. 

Junrong Zheng and Jitao Chen at Peking University, Beijing, and co-workers, have designed a novel cathode that improves the long-term stability of ZIBs during repeated recharging. ZIBs are non-toxic and have higher storage capacity than lithium-ion batteries, but interference from zinc ions inserting themselves into the layered structures of cathodes impacts on their stability and efficiency. 

The researchers made their cathode from a zinc-vanadium oxide material, using layered nanosheets made from tiny, ornate structures called ‘nanoflowers’ linked together. The large surface area of the nanoflowers provided abundant contact between the electrode and electrolyte, and short paths for zinc ions to follow, limiting their dispersion. The resulting battery remained stable over 20,000 recharging cycles, retaining a capacity of 96 per cent – a significant improvement over earlier designs. 

“The combination of excellent electrochemical performance, good safety of [the] aqueous electrolyte, low-cost electrode material […], and easy battery assembly makes the battery promising for grid-scale energy storage applications,” the authors say in their paper, published in Science Advances. 

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