“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. The hope is that this battery technology, even with lower performance than the expensive Li-ion batteries, will eventually offer a solution for these situations,” says Reverant Crispin, professor of organic electronics at Linköping University.
Stable battery
The battery is stable, as it can be used over 8000 cycles while maintaining about 80% of its performance. Additionally, the battery retains its charge for approximately one week, significantly longer than other similar zinc-based batteries that discharge in just a few hours.
Although zinc-based batteries are already on the market, primarily as non-rechargeable batteries, they are predicted to complement and, in some cases, replace lithium-ion batteries in the long run when the feature of rechargeability is properly introduced.
“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. Therefore, our sustainable battery offers a promising alternative where energy density is not critical,” says Ziyauddin Khan, a researcher at the Laboratory of Organic Electronics at LiU.
Cheap and recyclable
The issue with zinc batteries has primarily been poor durability due to zinc reacting with the water in the battery’s electrolyte solution. This reaction leads to the generation of hydrogen gas and dendritic growth of the zinc, rendering the battery essentially unusable.
To stabilise the zinc, a substance called potassium polyacrylate based water-in-polymer salt electrolyte (WiPSE) is used. What the researchers at Linköping have now demonstrated is that when WiPSE is used in a battery containing zinc and lignin, stability is very high.
“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,” says Ziyauddin Khan.
Scalable
Currently, the batteries developed in the lab are small. However, the researchers believe that they can create large batteries, roughly the size of a car battery, thanks to the abundance of both lignin and zinc at low cost. However, mass production would require the involvement of a company.
Reverant Crispin asserts that Sweden’s position as an innovative country enables it to assist other nations in adopting more sustainable alternatives.
“We can view it as our duty to help low-income countries avoid making the same mistakes we did. 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,” says Reverant Crispin.
The research was primarily funded by the Knut and Alice Wallenberg Foundation through the Wallenberg Wood Science Centre, the Swedish Research Council, Åforsk, the Swedish government’s strategic research area on advanced functional materials (AFM) at Linköping University, and Vinnova through Fun-Mat II. The long-term collaboration with Ligna Energy AB within the SESBC center is funded by the Swedish Energy Agency.
Article: Water-in-Polymer Salt Electrolyte for Long-Life Rechargeable Aqueous Zinc-Lignin Battery, Divyaratan Kumar, Leandro R. Franco, Nicole Abdou, Rui Shu, Anna Martinelli, C. Moyses Araujo, Johannes Gladisch, Viktor Gueskine, Reverant Crispin & Ziyauddin Khan; Energy & Environmental Materials 2024, published online 7 May 2024. DOI: 10.1002/eem2.12752
