The Future Looks Better For Zinc Chemistry Batteries

King Abdullah University of Science and Technology researchers have made a prototype of an anode-free, zinc-based battery that uses low-cost, naturally abundant materials.

The research group has reported therir progress in in ACS’s Nano letters.

Aqueous zinc-based batteries have been previously explored for grid-scale energy storage because of their safety and high energy density. In addition, the materials used to make them are naturally abundant. However, the rechargeable zinc batteries developed so far have required thick zinc metal anodes, which contain a large excess of zinc that increases cost. Also, the anodes are prone to forming dendrites – crystalline projections of zinc metal that deposit on the anode during charging – that can short-circuit the battery.

Yunpei Zhu, Yi Cui and Husam Alshareef wondered whether a zinc anode was truly needed. Drawing inspiration from previous explorations of “anode-free” lithium and sodium-metal batteries, the researchers decided to make a battery in which a zinc-rich cathode is the sole source for zinc plating onto a copper current collector.

In their battery, the researchers used a manganese dioxide cathode that they pre-intercalated with zinc ions, an aqueous zinc trifluoromethanesulfonate electrolyte solution and a copper foil current collector.

During charging, zinc metal gets plated onto the copper foil, and during discharging the metal is stripped off, releasing electrons that power the battery. To prevent dendrites from forming, the researchers coated the copper current collector with a layer of carbon nanodiscs. This layer promoted uniform zinc plating, thereby preventing dendrites, and increased the efficiency of zinc plating and stripping.

The battery showed high efficiency, energy density and stability, retaining 62.8% of its storage capacity after 80 charging and discharging cycles. The anode-free battery design opens new directions for using aqueous zinc-based batteries in energy storage systems, the researchers said.

We might note that zinc chemistry offer an huge drop in materials expense for rechargeable batteries. The recharge capacity fall off rate looks high, but this research is of the first lab prototype. Further research and development might well take this design in commercial viability soon. The press release isn’t including any notation of high cost or process that would drive a high consumer price. A low price, 500 good recharge cycles and no toxicity would be very consumer friendly, indeed.

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