Orbital hybridization-engineered electronic structure in multicomponent sulfides boosts the performance of polysulfide/iodide flow batteries

Abstract

Despite their attractive features of high energy density, low cost, and safety, polysulfide/iodide flow batteries (SIFBs) are hampered by the sluggish kinetics of the iodide redox couple, which restricts overall performance. Multicomponent sulfides are demonstrated as promising catalysts for accelerating I⁻/I₃⁻ redox reactions. Concurrently, the enhanced configurational entropy arising from multinary compositions drives synergistic effects among constituent elements, establishing a viable pathway to optimize catalytic performance. Building on these foundations, this work introduces a targeted orbital hybridization-optimized electron density strategy to enhance the catalytic activity. Implementing this concept, we developed an in-situ solvothermal synthesis process for an entropy-enhanced AgCuZnSnS₄ loaded graphite felt (ACZTS/GF) electrode. The engineered electrode demonstrates exceptional electrocatalytic performance with improved bulk conductivity and interfacial charge transfer kinetics within a SIFB. The cell achieves a high energy efficiency of 88.5% at 20 mA·cm⁻² with 10% state-of-charge. Furthermore, the battery delivers a maximum power density of 119.8 mW·cm⁻² and exhibits excellent long-term cycling stability. These significant results stem from orbital hybridization-driven electronic state optimization and entropy effect-induced synergistic catalysis.

Keywords

multicomponent sulfides / electronic properties / synergistic effect / polysulfide/iodide redox flow batteries

References

[1] D. Ma, B. Hu, W.D. Wu, et al., Highly active nanostructured CoS₂/CoS heterojunction electrocatalysts for aqueous polysulfide/iodide redox flow batteries, Nat. Commun., 10(2019), No. 1, art. No. 3367.

[2] Z.G. Wang, G.L. Lu, T.R. Wei, et al., Synergy of single atoms and sulfur vacancies for advanced polysulfide–iodide redox flow battery, Nat. Commun., 16(2025), No. 1, art. No. 2885.

[3] Xin XK, He M, Han W, Jung J, Lin ZQ. Low-cost copper zinc tin sulfide counter electrodes for high-efficiency dye-sensitized solar cells. Angew. Chem. Int. Ed., 2011, 50(4911739

[4] Huang SS, He QQ, Zai JT, et al.. The role of Mott–Schottky heterojunctions in PtCo–Cu₂ZnGeS₄ as counter electrodes in dye-sensitized solar cells. Chem. Commun., 2015, 51(438950

[5] J. Liu, L.T. Ren, Y. Wang, X.W. Lu, M.Y. Zhou, and W. Liu, A highly-stable bifunctional NiCo₂S₄ nanoarray@carbon paper electrode for aqueous polysulfide/iodide redox flow battery, J. Power Sources, 561(2023), art. No. 232607.

[6] T.T. Tsega, J.T. Zai, C.W. Lai, X.H. Li, and X.F. Qian, Earth-abundant CuFeS₂ nanocrystals@graphite felt electrode for high performance aqueous polysulfide/iodide redox flow batteries, Chin. J. Struct. Chem., 43(2024), No. 1, art. No. 100192.

[7] L. Lin, K. Wang, A. Sarkar, et al., High-entropy sulfides as electrode materials for Li-ion batteries, Adv. Energy Mater., 12(2022), No. 8, art. No. 2103090.

[8] Y.G. Yao, Q. Dong, A. Brozena, et al., High-entropy nanoparticles: Synthesis–structure–property relationships and data-driven discovery, Science, 376(2022), No. 6589, art. No. eabn3103.

[9] M.J. Cui, C.P. Yang, B.Y. Li, et al., High-entropy metal sulfide nanoparticles promise high-performance oxygen evolution reaction, Adv. Energy Mater., 11(2021), No. 3, art. No. 2002887.

[10] J.Y. Jiang, Y.F. Xu, Z. Wang, H.B. Zhang, Q. Xu, and Y.J. Li, High-entropy nitrides from dual entropic and enthalpic forces for high-efficiency oxygen evolution reaction, Energy Mater., 5(2025), No. 2, art. No. 500019.

[11] Dudarev SL, Botton GA, Savrasov SY, Humphreys CJ, Sutton AP. Electron-energy-loss spectra and the structural stability of nickel oxide: An LSDA+U study. Phys. Rev. B, 1998, 57(31505

[12] Clark SJ, Segall MD, Pickard CJ, et al.. First principles methods using CASTEP. Z. Kristallogr., 2005, 220(5–6567

[13] Gao N, Zhang RB, Chen BK, Zhang JF, Zhang XL, Rogach AL. Template synthesis of silver indium sulfide based nanocrystals performed through cation exchange in organic and aqueous media. Nano Res., 2021, 14(72321

[14] S. Ahmadi, N. Khemiri, A. Cantarero, and M. Kanzari, XPS analysis and structural characterization of CZTS thin films deposited by one-step thermal evaporation, J. Alloy. Compd., 925(2022), art. No. 166520.

[15] M. Vishwakarma, M. Kumar, M. Hendrickx, et al., Enhancing the hydrogen evolution properties of kesterite absorber by Si-doping in the surface of CZTS thin film, Adv. Mater. Interfaces, 8(2021), No. 10, art. No. 2002124.

[16] Ye F, Zhao BT, Ran R, Shao ZP. Facile mechanochemical synthesis of nano SnO₂/graphene composite from coarse metallic Sn and graphite oxide: An outstanding anode material for lithium-ion batteries. Chem-Eur J, 2014, 20(144055

[17] P. Jakóbczyk, G. Skowierzak, I. Kaczmarzyk, et al., Electrocatalytic performance of oxygen-activated carbon fibre felt anodes mediating degradation mechanism of acetaminophen in aqueous environments, Chemosphere, 304(2022), art. No. 135381.

[18] Kurnia F, Ng YH, Amal R, Valanoor N, Hart JN. Defect engineering of ZnS thin films for photoelectrochemical water-splitting under visible light. Sol. Energy Mater. Sol. Cells, 2016, 153: 179

[19] X.W. Gao, S.Y. Li, T.Z. Ren, et al., A high-entropy engineering on layered double hydroxide electrocatalyst with electronic structure reconstruction for ammonia synthesis, Adv. Funct. Mater., (2025), art. No. 2507512. DOI: https://doi.org/10.1002/adfm.202507512

[20] Q. Huang, B.K. Xia, M. Li, H.X. Guan, M. Antonietti, and S. Chen, Single-zinc vacancy unlocks high-rate H₂O₂ electrosynthesis from mixed dioxygen beyond Le Chatelier principle, Nat. Commun., 15(2024), No. 1, art. No. 4157.

[21] M. Rahimi, A. Molaei Dehkordi, and E.P.L. Roberts, Magnetic nanofluidic electrolyte for enhancing the performance of polysulfide/iodide redox flow batteries, Electrochim. Acta, 369(2021), art. No. 137687.

[22] Huang SS, Ma D, Hu ZJ, et al.. Synergistically enhanced electrochemical performance of Ni₃S₄–PtX (X = Fe, Ni) heteronanorods as heterogeneous catalysts in dye-sensitized solar cells. ACS Appl. Mater. Interfaces, 2017, 9(3327607

[23] X. Liu, Z. Chen, C.Y. Zhang, et al., High-areal-capacity manganese-based redox flow batteries via sodium diphosphate-modified electrolyte, Adv. Funct. Mater., (2025), art. No. 2509495. DOI: https://doi.org/10.1002/adfm.202509495

[24] H.D. Chen, Y.C. Qiu, Z.Y. Cai, et al., Topological insulator heterojunction with electric dipole domain to boost polysulfide conversion in lithium-sulfur batteries, Angew. Chem. Int. Ed., 64(2025), No. 13, art. No. e202423357.

[25] R.Q. Cheng, X.Q. He, M. Jiang, et al, f-p-d gradient orbital coupling induced spin state enhancement of atomic Fe sites for efficient and stable oxygen reduction reaction, Adv. Funct. Mater., 35(2025), No. 29, art. No. 2425138.

[26] Li ZJ, Lu YC. Polysulfide-based redox flow batteries with long life and low levelized cost enabled by charge-reinforced ion-selective membranes. Nat. Energy, 2021, 6(5517

RIGHTS & PERMISSIONS

University of Science and Technology Beijing