Metal-Free Aqueous Flow Battery with Novel Ultrafiltered Lignin as Electrolyte

• Published in: ACS sustainable chemistry & engineering Vol. 6; no. 4; pp. 5394 - 5400
• Main Authors: Mukhopadhyay, Alolika, Hamel, Jonathan, Katahira, Rui, Zhu, Hongli
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 02-04-2018; American Chemical Society (ACS)
• Subjects: abundance; ENERGY STORAGE; flow battery; lignin; organic electrolyte; redox active polymer; sustainability; Lignin; Abundance; Organic electrolyte; Redox active polymer; Flow battery; Sustainability
• ISSN: 2168-0485; 2168-0485
• DOI: 10.1021/acssuschemeng.8b00221

As the number of generation sources from intermittent renewable technologies on the electric grid increases, the need for large-scale energy storage devices is becoming essential to ensure grid stability. Flow batteries offer numerous advantages over conventional sealed batteries for grid storage. In this work, for the first time, we investigated lignin, the second most abundant wood derived biopolymer, as an anolyte for the aqueous flow battery. Lignosulfonate, a water-soluble derivative of lignin, is environmentally benign, low cost and abundant as it is obtained from the byproduct of paper and biofuel manufacturing. The lignosulfonate utilizes the redox chemistry of quinone to store energy and undergoes a reversible redox reaction. Here, we paired lignosulfonate with Br2/Br–, and the full cell runs efficiently with high power density. Also, the large and complex molecular structure of lignin considerably reduces the electrolytic crossover, which ensures very high capacity retention. The flowcell was able to achieve current densities of up to 20 mA/cm2 and charge polarization resistance of 15 ohm cm2. This technology presents a unique opportunity for a low-cost, metal-free flow battery capable of large-scale sustainable energy storage.