Anode-Free Zinc Battery Could One Day Provide Large-Scale Renewable Energy Storage
Renewable energy sources, such as wind and solar power, could help reduce the world’s dependence on fossil fuels. But first, power companies need a safe and cost-effective way to store energy for later use. Large lithium-ion batteries can do their job, but they run into limited lithium safety and availability issues. Now, researchers reporting on ACS’ Nano Letters have created a prototype of an anode-free zinc-based battery that uses cheap and naturally abundant materials.
Aqueous zinc-based batteries have previously been explored for network-scale energy storage due to their high energy safety and density. In addition, the ingredients used to make it abundant naturally. However, rechargeable zinc batteries developed so far require thick zinc metal anodes, which contain excess zinc which increases costs. In addition, anodes tend to form dendrite – a projection of zinc metal crystals that settle in anode during charging – which can lead to short-circuits in batteries. Yunpei Zhu, Yi Cui and Husam Alshareef wondered if zinc anodes were really needed. Taking inspiration from previous explorations of “anode-free” lithium and sodium-metal batteries, the researchers decided to create a battery in which zinc-rich cathodes were the only source for zinc plating to copper current collectors.
In their batteries, the researchers used manganese cathode dioxide which they pre-intercalated with zinc ions, a solution of zinc electrolyte trifluoromethanesulfonate and a collector of copper foil currents. During charging, the zinc metal will be coated into copper foil, and during use the metal is released, releasing electrons that power the battery. To prevent the formation of dendrite, the researchers coated copper current collectors with layers of carbon nanodisks. This coating promotes uniform zinc coating, thus preventing dendrite, and improving the efficiency of zinc coating and stripping. The battery demonstrates high efficiency, density and energy stability, maintaining 62.8% of its storage capacity after 80 cycles of charging and usage.