Dual-use rechargeable battery
by Simon Mansfield
Los Angeles CA (SPX) Jun 28, 2023
In the quest to advance the field of energy storage, researchers from Tsinghua University in Beijing, China, have developed an innovative battery system. The novel hybrid battery system not only stores and provides electricity but also generates valuable chemicals in a flow system, thereby increasing the cost efficiency of the battery operation. This exciting development blurs the lines between conventional rechargeable batteries, which store electricity in their electrodes, and redox flow batteries that store energy in attached chemicals.
The research team, led by Haohong Duan, designed a hybrid cell that exploits the qualities of both types of batteries and expands upon them, investigating whether such batteries can produce additional chemicals while performing their primary task of energy storage and provision. Furfural-a small molecule derived from common pentose sugars in agricultural biomass-serves as the cornerstone of this system. It has been viewed as a significant platform chemical due to its ability to produce a range of intermediates for various applications.
During operation, the novel furfural-nickel hydroxide battery converts furfural into either furfuryl alcohol or furoic acid, two value-added chemicals. When oxidized, furfural turns into furoic acid, a food preservative and an intermediary in the creation of pharmaceuticals and fragrances. When furfural is reduced, it morphs into furfuryl alcohol, a precursor to resins, flavors, and drugs.
The secret sauce of this battery lies in a bifunctional metal catalyst used for the anode. This catalyst, crafted from a rhodium-copper single-atom alloy, is capable of transforming the electrolyte-containing furfural into furfuryl alcohol when the battery is charged. As the battery discharges, the furfural morphs into furoic acid. For the cathode, the researchers identified a cobalt-doped nickel hydroxide material, a similar substance to those found in conventional nickel-zinc or nickel-metal hydride batteries.
Together, these components create a true dual-use battery system. After being charged via a solar cell, four series-connected hybrid batteries were shown to power a range of devices, such as LED lights and smartphones. Simultaneously, the batteries produced furfuryl alcohol and furoic acid throughout the battery cycling. The generated chemicals were then transported away via a flow system.
Upon evaluation, the authors concluded that the new hybrid battery is comparable to many common batteries in terms of energy density and power density. However, it stands out by providing both power and value-added chemicals at the same time. When storing 1 kWh of energy, the battery system generates 0.7 kg of furfuryl alcohol. When providing a power of 0.5 kWh-enough to run a refrigerator for several hours-1 kg of furoic acid is produced.
This isn’t a simple process, however. The system requires a continuous supply of furfural, and the byproduct chemicals must be separated from the electrolyte. While this novel concept presents an exciting stride toward improving the sustainability and cost effectiveness of rechargeable batteries, further development is needed to refine the system. Nonetheless, the research indicates a promising direction in the future of energy storage technology and could significantly influence the energy sector by transforming our perception of batteries from simple energy storage units to efficient chemical generators.