This Zinc-and-Lignin Battery Promises Cheap, Eco-Friendly Storage for Solar Power

Researchers from Linköping University, Karlstad University, Chalmers University of Technology, and Uppsala University have developed a low-cost eco-fiendly battery that could make storing solar power more accessible around the world — using a chemistry of zinc and lignin.

"Solar panels have become relatively inexpensive, and many people in low-income countries have adopted them. However, near the equator, the sun sets at around 6 PM, leaving households and businesses without electricity," explains Reverant Crispin, co-corresponding author on the paper detailing the new battery. "The hope is that this battery technology, even with lower performance than the expensive Li-ion [lithium ion] batteries, will eventually offer a solution for these situations."

The team's battery is based on zinc and lignin, environmentally-friendly and low-cost materials, rather than the lithium of most high-capacity or lead of deep-discharge solar-connected batteries. In use, it roughly matches the storage density of lead acid — but without requiring toxic lead in its production.

"While lithium-ion batteries are useful when handled correctly, they can be explosive, challenging to recycle, and problematic in terms of environmental and human rights issues when specific elements like cobalt are extracted," adds co-corresponding author Ziyauddin Khan. "Therefore, our sustainable battery offers a promising alternative where energy density is not critical. Both zinc and lignin are super cheap, and the battery is easily recyclable. And if you calculate the cost per usage cycle, it becomes an extremely cheap battery compared to lithium-ion batteries."

The prototype batteries developed by the team were tested to over 8,000 charge-discharge cycles, retaining around 80 percent of its original performance at the end. The researchers have also successfully resolved previous issues with zinc-based batteries, using a potassium polyacrylate-based water-in-polymer salt electrolyte (WiPSE) to provide longevity without off-gassing and dendritic growth and the ability to retain a charge for more than a week — a big improvement over previous designs, which lost charge over a period of hours.

"We can view it as our duty to help low-income countries avoid making the same mistakes we did," Crispin concludes. "When they build their infrastructure, they need to start with green technology right away. If unsustainable technology is introduced, it will be used by billions of people, leading to a climate catastrophe."

The team's work has been published under open-access terms in the journal Energy & Environmental Materials.

Main article image courtesy of Thor Balkhed.