Researchers from Tsinghua University in Beijing, China, have made a significant advancement in battery technology by developing a hybrid cell that not only stores and supplies electricity but also produces valuable chemicals in a flow system. Unlike traditional rechargeable batteries that store electricity in their electrode materials, and redox flow batteries that utilize chemicals stored in tanks attached to the electrodes, this new battery system combines both concepts.
The key innovation lies in the use of a bifunctional metal catalyst, specifically a rhodium-copper single-atom alloy, which acts as the anode catalyst. This catalyst enables the smooth conversion of furfural, a molecule derived from pentose sugars found in agricultural biomass, into either furfuryl alcohol or furoic acid, depending on whether the battery is being charged or discharged. Furfuryl alcohol is a precursor for resins, flavors, and drugs, while furoic acid is a food preservative and an intermediate compound in the synthesis of pharmaceuticals and fragrances.
For the cathode, the researchers identified a cobalt-doped nickel hydroxide material similar to those used in conventional nickel-zinc or nickel-metal hydride batteries. This combination of catalysts and electrode materials allows the hybrid battery to operate as a true dual-use system. During charging, it can power various devices such as LED lights and smartphones, while simultaneously producing furfuryl alcohol. Conversely, during discharging, it generates furoic acid while providing power.
The hybrid battery demonstrates energy density and power density comparable to other common battery types. When storing 1 kWh of energy, it produces 0.7 kg of furfuryl alcohol, and when providing 0.5 kWh of power (enough to run a refrigerator for a couple of hours), it yields 1 kg of furoic acid. However, the continuous supply of furfural is required, and the produced chemicals must be separated from the electrolyte.
While this hybrid battery represents a significant step forward in terms of sustainability and cost-effectiveness, further development and refinement are still necessary. Nonetheless, this research holds promise for enhancing the capabilities of rechargeable batteries by integrating the production of valuable chemicals into their operation. The findings of this study have been published in the journal Angewandte Chemie International Edition.