A novel lithium-ion battery chemistry developed by UNSW chemists using food-based acids could offer a pathway to cheaper batteries while also reducing impacts from food waste on the environment and the economy.
In a prototype developed and patented by UNSW, researchers have created a replacement for graphite compounds with acids found in sherbet and winemaking, reducing material costs while improving energy storage capacity.
Taking the concept a step further, the research team is also looking at diverting diverse bio-waste streams from landfill to use in batteries, including creating lithium-ion battery anodes from materials as humble as coffee grounds.
Small battery, outsized benefits
The current prototype pouch cell is a single-layer model similar to those used in handheld devices like mobile phones, only smaller.
“We’ve developed an electrode that can significantly increase the energy storage capability of lithium-ion batteries by replacing graphite with compounds derived from food acids, such as tartaric acid [that occurs naturally in many fruits] and malic acid [found in some fruits and wine extracts],” UNSW Science lead researcher Professor Neeraj Sharma said.
The food-derived acid is readily available from food waste products while being less aggressive and more environmentally friendly than traditional materials.
“[Our battery component] could potentially use food acids from food waste streams, [reducing their environmental and economic impact],” Professor Sharma explained.
“Its processing uses water rather toxic solvents, so we’re improving the status quo across multiple areas.”
Food waste costs $36.6 billion every year
Apart from being a cheaper component with less environmental impact from mineral extraction and reagent use, the new acid chemistry also offers a value-add stream for products previously disposed of as waste.
The Australian economy spends $36.6 billion each year on managing food waste, also accounting for about 3% of the country's total greenhouse gas emissions.
“By using waste produced at scale for battery components, the industry can diversify their inputs while addressing both environmental and sustainability concerns,” said Professor Sharma, who leads the solid state and materials chemistry group at UNSW.
The need for purpose-built, cost-effective and environmentally-sound batteries is only growing as global economies move toward net-zero and decarbonisation.
“Using food acids to produce water-soluble metal dicarboxylates [electrode materials] presents a competitive alternative to graphite used in the majority of lithium-ion batteries that can, as we’ve demonstrated, optimise battery performance, renewability and cost to better support battery demand,” Professor Sharma concluded.
The future is… coffee?
Turning waste streams into useful products to support the energy transition addresses multiple economic, social and environmental issues, offering cross-sectional benefits.
According to ANSTO, 8 million tonnes of coffee grounds are tossed into landfill every year, representing a potentially valuable biomass stream.
A collaboration between the UNSW Sustainable Materials Research and Technology centre, School of Chemistry at the University of NSW and CSIRO Clayton revealed coffee waste-derived carbon frameworks can improve the stability of lithium-sulphur (Li-S) batteries.
Li-S batteries are capable of holding 10 times the energy capacity of current lithium-ion chemistries but suffer from stability limitations that reduce their capacity over time.
The team found that the electrodes which had been prepared with the pyrolysed coffee grounds exhibited a more stable chemistry,” said Dr Cowie, a co-author on the paper published in Carbon Trends.
According to the team’s data, the new approach essentially solved the stability problem, achieving 98% efficiency even after 100 charge/discharge cycles.
“Such enhanced stability afforded by the pyrolysed coffee is a promising achievement in the treatment of waste-derived carbons for applications in energy storage,” the paper concluded.