Researchers at the University of Michigan have developed a structural, rechargeable, zinc battery with a cartilage-like solid electrolyte that is resistant to damage. Structural batteries are currently being actively researched because of their multiple benefits, including weight reduction and extension of range. However, safety concerns have prevented their implementation.
“A battery that is also a structural component has to be light, strong, safe and have high capacity,” said research lead Nicholas Kotov, a professor of chemical and materials science engineering at Michigan. “Unfortunately, these requirements are often mutually exclusive.”
Zinc is an established structural and battery material, but has only been used in single-use batteries as it forms rigid dendrites on repeated recharge cycles. To overcome the dendrite problem, Kotov’s team developed a solid electrolyte from a composite of branched aramid nanofibres (BANFs) and poly(ethyleneoxide). Based on the structure of cartilage, the BANFs mimic the tissue’s tough collagen and resist penetration from dendrites, while the poly(ethyleneoxide) replicates the cartilage’s softer components and allows zinc ions to flow between the battery’s two electrodes.
“Nature does not have zinc batteries, but it had to solve a similar problem,” Kotov said. “Cartilage turned out to be a perfect prototype for an ion-transporting material in batteries. It has amazing mechanics, and it serves us for a very long time compared to how thin it is. The same qualities are needed from solid electrolytes separating cathodes and anodes in batteries.”
The prototype battery can run for more than 100 cycles at 90 percent capacity. After piercing the battery with a knife multiple times to demonstrate its durability, the team found it continued to discharge close to its design voltage.
The paper can be read in the journal ACS Nano.