Research 01

Long-Duration Flow Batteries

Our research on aqueous flow batteries addresses crossover, electrode losses and cost. We design selective membranes to retain redox-active species while allowing charge-balancing ions to pass, and investigate catalysts to lower overpotentials in hybrid flow batteries. To extend service life and improve cost-effectiveness, we study low-cost active materials alongside electrolyte formulation and cell design.

Aqueous systems · Low-cost redox-active materials · Selective membranes

Flow battery with catholyte and anolyte circuits and a central separator — Flow battery architecture and key degradation pathways: membrane crossover, electrode fouling, electrolyte decomposition and precipitation.

Microporous polymer membrane schematic showing selective gates — Innovative Microporous Membranes

Catalyst surface schematic and electron micrograph — Innovative Catalysts for Hybrid RFBs

Bar chart comparing system costs for vanadium, iron–zinc, iron–sulfur and all-iron flow batteries — Our Focus: Cost-Effective Systems

Current Projects

Membranes (RFB Lifetime)

We engineer polymer backbones and functional groups at the molecular level to create a family of membranes based on polymers of intrinsic microporosity. These membranes allow charge-balancing ions to pass while restricting crossover of redox-active species, helping extend the operating life of redox flow batteries.

Related publications

Membrane design and transport mechanisms

J. Liu, M. Xie, Z. Wang, H. Li, J. Xie, P. Liu, Q. Wang, X. Yan, M. Shi, L. Chai, Y. Luo, A. Tang, R. Tan, L. Zhang, “Toward Rational Design of Aqueous Battery Membranes Beyond the Selectivity–Conductivity Trade-Off,” Advanced Science, 2026, e78245. DOI
X. Zhou, J. D. Akoto, R. Tan, J. Ma, “Membrane Engineering for Battery Systems: Bridging Design Principles and Frontier Applications,” Energy & Environmental Materials, 2026, 9(3), e70192.
C. Wei, W. Fan, Y. Luo, N. Jia, C. Hong, J. Yan, X. Liu, R. Tan, “‘Small’Technology, Big Power: Micropore Engineering for High‐Performance Flow Battery Membranes,” Small, 2026, 22(18), e13508.
J. Liu, C. Ye, Y. Ma, R. Tan, X. Wang, et al, “Ion‐Selective Microporous Membranes via One‐Step Copolymerization Enable High‐Performance Redox Flow Batteries,” Advanced Functional Materials, 2026, 36(12), e13137.
T. Wong, Y. Yang, R. Tan, A. Wang, Z. Zhou, Z. Yuan, et al, “Sulfonated poly (ether-ether-ketone) membranes with intrinsic microporosity enable efficient redox flow batteries for energy storage,” Joule, 2025, 9(2).
A. Wang, C. Breakwell, F. Foglia, R. Tan, L. Lovell, et al, “Selective ion transport through hydrated micropores in polymer membranes,” Nature, 2024, 635(8038), 353-358. DOI
A. Wang, R. Tan, D. Liu, J. Lu, X. Wei, et al, “Ion‐selective microporous polymer membranes with hydrogen‐bond and salt‐bridge networks for aqueous organic redox flow batteries,” Advanced Materials, 2023, 35(12), 2210098.
P. Zuo, Y. Li, A. Wang, R. Tan, Y. Liu, et al, “Sulfonated microporous polymer membranes with fast and selective ion transport for electrochemical energy conversion and storage,” Angewandte Chemie, 2020, 132(24), 9651-9660.
R. Tan, A. Wang, R. Malpass-Evans, R. Williams, et al, “Hydrophilic microporous membranes for selective ion separation and flow-battery energy storage,” Nature Materials, 2020, 19(2), 195-202. DOI

Separator and membrane performance in flow cells

W. Yoopensuk, G. Mohan, N. Suppanucroa, J. Sangsawang, V. Aupama, R. Tan, et al, “Functionalized zirconium-based metal-organic framework separator for enhanced ionic conductivity in zinc-polyiodide flow batteries,” Journal of Energy Storage, 2026, 178, 123628. DOI
R. Tan, A. Wang, C. Ye, J. Li, D. Liu, B. P. Darwich, et al, “Thin film composite membranes with regulated crossover and water migration for long‐life aqueous redox flow batteries,” Advanced Science, 2023, 10(20), 2206888. DOI
C. Ye, R. Tan, A. Wang, J. Chen, B. C. Gándara, et al, “Long‐life aqueous organic redox flow batteries enabled by amidoxime‐functionalized ion‐selective polymer membranes,” Angewandte Chemie, 2022, 134(38), e202207580.
C. Ye, A. Wang, C. Breakwell, R. Tan, C. G. Bezzu, E. Hunter-Sellars, et al “Development of efficient aqueous organic redox flow batteries using ion-sieving sulfonated polymer membranes,” Nature Communications, 2022, 13(1), 3184.

Catalysts (RFB Efficiency)

We design porous electrocatalysts to accelerate electrode redox reactions, reduce kinetic losses and improve energy efficiency in redox flow batteries. We apply this approach to air-based, hydrogen-based and sulfur-based systems.

Related publications

Hydrogen evolution catalysis

J. Mai, Y. Zhang, H. He, Y. Luo, X. Zhou, K. Hu, G. Liu, M. K. Sugumar, C. T. J. Low, X. Liu, R. Tan, “Metal-support interface engineering for stable and enhanced hydrogen evolution reaction,” Materials Today Chemistry, 2024, 38, 102079. DOI

Related hybrid flow-cell platform

Y. Xia, M. Ouyang, V. Yufit, R. Tan, A. Regoutz, A. Wang, W. Mao, B. Chakrabarti, A. Kavei, Q. Song, A. R. Kucernak, N. P. Brandon, “A cost-effective alkaline polysulfide-air redox flow battery enabled by a dual-membrane cell architecture,” Nature Communications, 2022, 13(1), 2388. DOI

Related catalyst design and oxygen electrocatalysis

G. Liao, S. Li, Z. Zhou, Q. Yu, K. Du, P. Ren, R. Tan, N. Li, Z. Feng, K. Xie, “Plasma-activated vacancy-rich RuO₂/Co₃O₄ heterostructures enable high-performance borohydride electro-oxidation for direct borohydride fuel cells,” Chemical Engineering Journal, 2026, 550, 183801. DOI
H. Wang, Z. Feng, J. Yang, Y. Ma, W. Jing, Z. Tang, S. Li, R. Tan, “Data-driven strategies for decoding structure- reactivity relationships in porous electrocatalysis,” Chemical Communications, 2026.
S. Li, S. Wang, Q. Chen, … R. Tan & Z. Feng, “Synergistic boron-based nanocrystal and amorphous Ni–Fe–B catalyst for high-performance flexible zinc-air batteries,” Catalysis Science & Technology, 2026, 16(4), 1411-1420.
H. Wu, S. Li, D. Yang, Y. Wang, S. Wang, Y… R. Tan & Z. Feng, “Plasma-engineered CuOx with Cu+/Cu2+ states and oxygen vacancies for flexible zinc-air batteries,” Journal of Alloys and Compounds, 2026, 188808.
F. Zhan, L. Huang, Y. Luo, M. Chen, R. Tan, X. Liu, G. Liu, Z. Feng, “Recent advances on support materials for enhanced Pt-based catalysts: applications in oxygen reduction reactions for electrochemical energy storage,” Journal of Materials Science, 2025, 60(5), 2199-2223.
S. Li, Z. Xin, Y. Luo, J. Pan, G. Liao, Q. Li, Y. Sun, Z. Feng, R. Tan, “Recent advances in the development of single atom catalysts for oxygen evolution reaction,” International Journal of Hydrogen Energy, 2024, 82, 1081-1100.
W. Jia, Q. Lu, T. Tian, G. Pan, R. Tan, B. He, J. Liu, “Self-templated fabrication of P-doped CoMoO4-Co3O4 hollow nanocages for the efficient oxygen evolution reaction,” Nanoscale, 2024.
K. Hu, Y. Zhang, J. Zhu, J. Mai, G. Liu, M. K. Sugumar, X. Liu, F. Zhan, R. Tan, “Nano-engineered catalysts for high-performance oxygen reduction reaction,” Chinese Chemical Letters, 2023, 109423.
L.-L. Tian, J. Yang, M.-Y. Weng, R. Tan, J.-X. Zheng, H.-B. Chen, Q.-C. Zhuang, L.-M. Dai, F. Pan, “Fast Diffusion of O2 on Nitrogen-Doped Graphene to Enhance Oxygen Reduction and Its Application for High-Rate Zn–Air Batteries,” ACS Applied Materials & Interfaces, 2017, 9(8), 7125-7130.
J. Yang, J. Hu, M. Weng, R. Tan, L. Tian, J. Yang, J. Amine, J. Zheng, H. Chen, F. Pan, “Fe-Cluster Pushing Electrons to N-Doped Graphitic Layers with Fe3C(Fe) Hybrid Nanostructure to Enhance O2 Reduction Catalysis of Zn-Air Batteries,” ACS Applied Materials & Interfaces, 2017, 9(5), 4587-4596.

Active Materials (RFB Cost-Effectiveness)

We focus on low-cost, stable redox-active materials and pair them with selective membranes to control crossover and capacity fade. By developing the active materials and membranes together, we aim to advance cost-effective flow battery systems beyond Technology Readiness Level (TRL) 6.

Related publications

Aqueous flow-cell design and cycling durability

X. Zhao, J. Yu, N. Jia, C. Hong, Y. Luo, W. Jing, Z. Feng, X. Liu, R. Tan, “High‐Energy‐Density Redox Flow Batteries: Mechanisms, Design Strategies, and Recent Progress,” Chemistry–A European Journal, 2026, 32(24), e03595.
R. Tan, A. Wang, C. Ye, J. Li, D. Liu, B. P. Darwich, et al, “Thin film composite membranes with regulated crossover and water migration for long‐life aqueous redox flow batteries,” Advanced Science, 2023, 10(20), 2206888. DOI
C. Ye, R. Tan, A. Wang, J. Chen, B. C. Gándara, et al, “Long‐life aqueous organic redox flow batteries enabled by amidoxime‐functionalized ion‐selective polymer membranes,” Angewandte Chemie, 2022, 134(38), e202207580.
C. Ye, A. Wang, C. Breakwell, R. Tan, C. G. Bezzu, E. Hunter-Sellars, et al “Development of efficient aqueous organic redox flow batteries using ion-sieving sulfonated polymer membranes,” Nature Communications, 2022, 13(1), 3184.
Y. Xia, M. Ouyang, V. Yufit, R. Tan, A. Regoutz, A. Wang, W. Mao, B. Chakrabarti, A. Kavei, Q. Song, A. R. Kucernak, N. P. Brandon, “A cost-effective alkaline polysulfide-air redox flow battery enabled by a dual-membrane cell architecture,” Nature Communications, 2022, 13(1), 2388. DOI

Related redox-active material design

A. Wang, R. Tan, C. Breakwell, et al, “Solution-processable redox-active polymers of intrinsic microporosity for electrochemical energy storage,” Journal of the American Chemical Society, 2022, 144(37), 17198-17208.