Open Access Received: 22 July 2026   |   Accepted: 02 September 2026   |   Published: 07 September 2026

VANADIUM REDOX FLOW BATTERIES FOR LONG-DURATION ENERGY STORAGE: RECENT ADVANCES IN ELECTROLYTE STABILITY, POLYMER MEMBRANE SELECTIVITY, ELECTRODE ENGINEERING AND CAPACITY-FADE MITIGATION

Bokhodir B. Gulyamov¹, Ernazar R. Toxtabaev¹, Gulmira В. Khojieva^1,2, Oybek M. Tursunkulov¹, Shokir G’.Khojiev¹

¹ Center for Advanced Technologies under the Academy of Sciences of the Republic of Uzbekistan, University Street, 3A, 100174, Tashkent, Uzbekistan
² Department of Physical Chemistry, Faculty of Chemistry, National University of Uzbekistan, University Street 4, 100174 Tashkent, Uzbekistan

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Abstract. Vanadium redox flow batteries (VRFBs) are promising systems for stationary long-duration energy storage because they use aqueous non-flammable electrolytes, allow independent scaling of energy and power, and offer long cycle life. Their wider deployment, however, remains limited by coupled materials and engineering challenges, including electrolyte instability, V(V) precipitation, vanadium crossover, water migration, sluggish carbon-electrode kinetics, hydraulic losses, capacity decay and vanadium-related cost. This review discusses recent progress in VRFB development with emphasis on the interactions between electrolyte chemistry, polymer membrane selectivity, electrode kinetics, stack design and long-term capacity retention. Particular attention is given to polymeric and polymer-composite ion-exchange membranes, including PFSA/Nafion-type membranes, hydrocarbon cation-exchange membranes, SPEEK-based composites, PBI/PBMI-type membranes, anion-exchange membranes and porous or nanofiltration membranes. Their conductivity-selectivity-stability trade-offs are considered in relation to vanadium crossover, water transport and capacity fade. The review also highlights key performance compromises, such as energy density versus electrolyte stability, membrane conductivity versus crossover suppression, electrode activity versus durability, and mass transport versus pumping loss. Finally, remaining challenges are outlined, including stable high-concentration electrolytes, low-cost selective polymer membranes, durable scalable electrodes, standardized capacity-decay diagnostics, stack-level validation and circular vanadium-electrolyte management.

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Key words. Vanadium redox flow battery; long-duration energy storage; polymer ion-exchange membrane; SPEEK; Nafion; PBI membrane; membrane selectivity; vanadium crossover; carbon felt electrodes; capacity decay


DOI: 10.66640/UJP-2026-5-00018

*Corresponding author: Shokir G’.Khojiev, Center for Advanced Technologies under the Academy of Sciences of the Republic of Uzbekistan, University Street, 3A, 100174, Tashkent, Uzbekistan

Citation: Bokhodir B. Gulyamov, Ernazar R. Toxtabaev, Gulmira В. Khojieva, Oybek M. Tursunkulov, Shokir G’.Khojiev, VANADIUM REDOX FLOW BATTERIES FOR LONG-DURATION ENERGY STORAGE: RECENT ADVANCES IN ELECTROLYTE STABILITY, POLYMER MEMBRANE SELECTIVITY, ELECTRODE ENGINEERING AND CAPACITY-FADE MITIGATION. Uzbekistan Journal of Polymers, Vol. 5(3) 2026: pp.55-92. DOI: 10.66640/UJP-2026-5-00018

©2026 Uzbekistan Journal of Polymers