“Compared with a lithium-ion device, the structure is quite simple and safe,” said Yang Yang, lead author of the paper, in the press release.
“It behaves like a battery but the structure is that of a supercapacitor. If we use it as a supercapacitor, we can charge quickly at a high current rate and discharge it in a very short time. But for other applications, we find we can set it up to charge more slowly and to discharge slowly like a battery.”
To make the battery-supercapacitor hybrid, the Rice team deposited a nickel layer on a backing material. They then etched the nickel layer to create pores five nanometers in diameter. The result is high surface area for storing ions.
After removing the backing, the nickel-based electrode material is wrapped around a solid electrolyte of potassium hyrodroxide in polyvinyl alcohol.
In testing, the researchers found that there was no degradation of the pore structure after 10 000 charge-discharge cycles, or any significant degradation of the electrode-electrolyte interface.