Scientists at Qingdao University have developed a new cathode material using nitrogen‑rich carbon dots that could be used for zinc‑ion batteries. Although there have been some reports on the hybridization of VO2 and VS2, their bagel-like hollow nanostructures synthesized in a simple one-step hydrothermal method exhibit great promise for the future energy storage.
Powering the Future with Zinc
Abstract Zn-ion batteries have been proposed as a promising option to lithium-ion systems with advantages of safety, cost, and eco-friendliness. ZIBs, operating with aqueous electrolytes distinguish themselves from their lithium-based counterparts and are indispensable for long-duration energy storage applications ever demanding e.g. in electric vehicles/householder and grid storage.
Specially, its cathode material usually determines the capacity, rate capability and cycle life of ZIBs, thus heavily limiting the feeble performance of ZIBs. Enter the revolutionary research out of Qingdao University.
Heterostructure with New Functionality
Based on an one-step hydrothermal method, the team successfully synthesized hollow nanospheres of VO2@VS2 that exhibited superior performance in zinc-ion batteries. The novel heterostructure is a marriage between vanadium disulfide (VS2) and vanadium dioxide (VO2), the latter helpful for responding to light, but weak in absorption; paired with VS2, VP-NS begets the best of both worlds.
Among ZIB cathode materials, VO2 is a focus because of its high theoretical capacity and zinc-ion intercalation properties. Nevertheless, the low electrical conductivity and poor rate performance severely restrict its practical applications. Thus, combining VO2 with highly conductive VS2 leads to the synthetic system that smartly enhances electronic conductivity, accelerates Zn-ion insertion/extraction kinetics and stabilizes the structure during long-term cycling.
First, the hierarchical structure with a large intersheet distance between VS2 enables an extremely fast zinc ion diffusion rate, and its high electrical conductivity complements well in electrochemical properties of VO2. This is said to contribute not only to an improved battery overall, but also the long-term integrity of the material.
Conclusion
The Qingdao University researchers have developed VO2@VS2 hollow nanospheres, which has been a major advance in the field of zinc-ion battery technology. Curing this new cathode material demonstrates great performance with the reversible capacity of 468 mAh g−1 and up to 85% after 1,000 cycles! Due to its new improved electronic platform which increased the Zn-ion transport, more robust electrochemical stability and lifetimes above of 10,000 cycles making it well-suited for low-cost and sustainable energy storage systems. With increasing demand for efficient, safe and environmentally friendly energy storage solutions, VO2@VS2 technology makes it possible to replace lithium-ion batteries with a new generation of zinc-ion batteries for the next era of high performance electric vehicles and grid-level energy storage applications.
