redox flow

lead acid

battery

hard carbon

flow batteries

cathode

batteries

lithium-sulfur batteries

quasi solid

Joule

•Near-neutral chemistry for rechargeable, aqueous-soluble, organic redox-flow batteries•Capacity fade rate of ∼0.01%/day, the longest lifetime for a quinone-based electrolyte•Meets technical criteria for commercialization of redox-flow batteries Electricity generation from renewable sources such as solar and wind can eliminate fossil-fuel-based systems if their intermittent output can be regulated using safe, cost-effective energy storage. Aqueous-soluble organic redox-flow batteries (RFBs) are a potentially safer, less expensive alternative to lithium ion batteries and vanadium flow batteries for long-discharge duration storage. We demonstrate a long-lifetime, organic-molecule-based RFB that can operate in weak alkaline conditions while maintaining an open-circuit voltage of over 1 V. The negative electrolyte comprises an anthraquinone functionalized with solubilizing carboxylate groups and the positive electrolyte comprises the food additive potassium ferrocyanide. The RFB can operate with an inexpensive membrane and shows a capacity fade rate that rivals the lowest ever reported for any RFB in the absence of rebalancing processes. This result adds the important attribute of long calendar life to quinone-based RFBs. We demonstrate a long-lifetime, aqueous redox-flow battery that can operate at a pH as low as 12 while maintaining an open-circuit voltage of over 1 V. We functionalized 2,6-dihydroxyanthraquinone (2,6-DHAQ) with highly alkali-soluble carboxylate terminal groups. The resulting negative electrolyte material 4,4′-((9,10-anthraquinone-2,6-diyl)dioxy)dibutyrate (2,6-DBEAQ) was six times more soluble than 2,6-DHAQ at pH 12. Symmetric cell cycling with 2,6-DBEAQ on both sides of the cell demonstrates a capacity fade rate of <0.01%/day and <0.001%/cycle. By pairing 2,6-DBEAQ with a potassium ferri-/ferrocyanide positive electrolyte and utilizing a non-fluorinated membrane, this near-neutral flow battery shows a capacity fade rate that is the lowest of any quinone and rivals the lowest ever reported for any...

Alkaline Quinone Flow Battery with Long Lifetime at pH 12