Wind and solar power are intermittent, and storing their output safely and cheaply remains one of the energy transition's hardest problems. Chemists Hélène Lebel and Dominic Rochefort of Université de Montréal, with Marc-Antoni Goulet of Concordia University, have developed a candidate solution: AzoBiPy, an organic molecule of the pyridinium family built from carbon, hydrogen, nitrogen and oxygen, which dissolves readily in water and acid. Their study appeared in the Journal of the American Chemical Society.
AzoBiPy is designed for redox flow batteries, in which energy is held in two external tanks of water-based electrolyte, so storage capacity and power can be scaled independently. Commercial flow batteries typically rely on vanadium, a non-renewable metal. In testing, a prototype ran for 70 consecutive days through 192 full charge-discharge cycles, losing only about 0.02 per cent of capacity per day and retaining nearly 99 per cent overall, a figure the researchers describe as exceptional for an organic molecule.
Because AzoBiPy exchanges two electrons per molecule, it stores roughly twice the energy of comparable single-electron compounds, and the water-based design is non-flammable, unlike lithium-ion cells. An earlier demonstration powered Christmas tree lights for eight hours from tanks holding about two tablespoons of solution each. The team is drafting a patent, exploring bio-based variants derived from wood or food residues, and expects the technology to reach wider use within 10 to 15 years.