Bioderived Molecular Electrodes for Next-Generation Energy-Storage Materials.

Nature-derived organic small molecules, as energy-storage materials, provide low-cost, recyclable, and non-toxic alternatives to inorganic and polymer electrodes for lithium-/sodium-ion batteries and beyond. Some organic carbonyl compounds have met or exceeded the voltages and gravimetric storage capacities achieved by traditional transition metal oxide-based compounds due to the metal-ion coupled redox and facile electron-transport capability of functional groups. Stability issues that previously limited the capacity of small organic molecules can be remediated with reactions to form insoluble salts, noncovalent interactions (hydrogen bonding and π stacking), loading onto substrates, and careful electrolyte selection. The cost-effectiveness and sustainability of organic materials may further be improved by employing porphyrin-based electrodes and multivalent-ion batteries utilizing abundant metals, such as aluminum and zinc. Finally, redox flow batteries take advantage of the solubility of organics for the development of scalable, high power density, and safe energy-storage devices based on aqueous electrolytes. Herein, the advantages and prospects of small molecule-based electrodes, with a focus on nature-derived organic and biomimetic materials, to realize the next-generation of green battery chemistry are reviewed.