FeNiS₂ quantum dot integration boosts enhanced reaction kinetics and cycle stability of SPAN nanofiber cathode for Li-S batteries

Abstract

Sulfurized polyacrylonitrile (SPAN) has been regarded as one of the most competitive cathode candidates for lithium-sulfur (Li-S) batteries, owing to its outstanding theoretical energy density, excellent structural durability, and minor self-discharge. Nevertheless, the intrinsically slow reaction kinetics of SPAN results in insufficient active sulfur utilization at high current rates, which severely restricts its rate performance and long-cycle stability. This study introduces FeNiS₂ Quantum Dots (QDs) as catalyst embedding in SPAN nanofibers (FeNiS₂ QDs@SPAN). Taking advantages of the ultra-small size, superior dispersibility and abundant catalytic sites of FeNiS₂ QDs, the redox kinetics and cycle performance of SPAN are significantly enhanced. Kinetic analyses and theoretical calculation demonstrate the uniformly dispersed FeNiS₂ QDs effectively reduce charge transfer resistance and facilitate conversion reaction. FeNiS₂ QDs@SPAN material exhibits high reversible capacity of 1,213 mAh g^-1 and an ultralow capacity decay of 0.034% per cycle over 1,000 cycles at 1 C. Remarkably, even at high rate of 5 C (8.37 A g^-1), it delivers a stable long-cycle capacity of 720 mAh g^-1 and demonstrates excellent cycling capability with a low fade rate of 0.029% per cycle over 450 cycles. FeNiS₂ QDs@SPAN material maintains good performance even under lean electrolyte conditions and a wide temperature range. This work underscores the significant potential of FeNiS₂ QDs as catalyst for achieving high performance sulfur cathode and advanced Li-S batteries.

Keywords

Lithium-sulfur batteries / FeNiS₂ quantum dots / catalytic conversion / reaction kinetics / high-rate performance

References

[1] Fang R.,Zhao S.,Sun Z.,Wang D. W.,Cheng H. M.,Li F.. More reliable lithium-sulfur batteries: status, solutions and prospects Adv. Mater. 2017 29 1606823

[2] Deng R.,Wang M.,Yu H..et al. Recent advances and applications toward emerging lithium-sulfur batteries: working principles and opportunities Energy Environ. Materials 2022 5 777 99

[3] Wang J.,He Y. S.,Yang J.. Sulfur-based composite cathode materials for high-energy rechargeable lithium batteries Adv. Mater. 2015 27 569 75

[4] Sun C.,Sheng J.,Zhang Q..et al. Self-extinguishing Janus separator with high safety for flexible lithium-sulfur batteries Sci. China Mater. 2022 65 2169 78

[5] Liu B.,Fang R.,Xie D..et al. Revisiting scientific issues for industrial applications of lithium-sulfur batteries Energy Environ. Mater. 2018 1 196 208

[6] Xue W.,Shi Z.,Suo L..et al. Intercalation-conversion hybrid cathodes enabling Li-S full-cell architectures with jointly superior gravimetric and volumetric energy densities Nat. Energy 2019 4 374 82

[7] Li H.,Li Y.,Zhang L.. Designing principles of advanced sulfur cathodes toward practical lithium‐sulfur batteries SusMat 2022 2 34 64

[8] Li J.,Li X.,Fan X..et al. Holey graphene anchoring of the monodispersed nano-sulfur with covalently-grafted polyaniline for lithium sulfur batteries Carbon 2022 188 155 65

[9] Li S.,Fan Z.. Encapsulation methods of sulfur particles for lithium-sulfur batteries: a review Energy Storage Mater. 2021 34 107 27

[10] Feng L.,Yu P.,Fu X..et al. Regulating polysulfide diffusion and deposition via rational design of core-shell active materials in Li-S batteries ACS Nano 2022 16 7982 92

[11] Zhou W.,Chen M.,Zhao D..et al. Confined Co₉S₈ nanocrystals into N/S-Co-doped carbon nanofibers as a chainmail-like electrocatalyst for high-performance lithium-sulfur batteries with high sulfur loading J. Colloid Interface Sci. 2022 625 187 96

[12] Xiao Z.,Li Z.,Li P.,Meng X.,Wang R.. Ultrafine Ti₃C₂ MXene nanodots-interspersed nanosheet for high-energy-density lithium-sulfur batteries ACS Nano 2019 13 3608 17

[13] Chu R.,Nguyen T. T.,Bai Y.,Kim N. H.,Lee J. H.. Uniformly controlled treble boundary using enriched adsorption sites and accelerated catalyst cathode for robust lithium-sulfur batteries Adv. Energy Mater. 2022 12 2102805

[14] Yuan S.,Xia M.,Liu Z..et al. Dual synergistic effects between Co and Mo₂C in Co/Mo₂C heterostructure for electrocatalytic overall water splitting Chem. Eng. J. 2022 430 132697

[15] Wang J.,Yang J.,Xie J.,Xu N.. A Novel conductive polymer-sulfur composite cathode material for rechargeable lithium batteries Adv. Mater. 2002 14 963 5

[16] Wei S.,Ma L.,Hendrickson K. E.,Tu Z.,Archer L. A.. Metal-sulfur battery cathodes based on PAN-sulfur composites J. Am. Chem. Soc. 2015 137 12143 52

[17] Zhao X.,Wang C.,Li Z.,Hu X.,Abdul Razzaq A.,Deng Z.. Sulfurized polyacrylonitrile for high-performance lithium sulfur batteries: advances and prospects J. Mater. Chem. A. 2021 9 19282 97

[18] Xie J.,Chen J.,Guo L..et al. Deciphering the sulfur-involved bonding interactions in sulfurized polyacrylonitrile: the formation thermodynamics and the roles in electrochemical characteristics ACS Nano 2025 19 3931 43

[19] Liu J.,Wang M.,Xu N.,Qian T.,Yan C.. Progress and perspective of organosulfur polymers as cathode materials for advanced lithium-sulfur batteries Energy Storage Mater. 2018 15 53 64

[20] Chen W. J.,Li B. Q.,Zhao C. X..et al. Electrolyte regulation towards stable lithium-metal anodes in lithium-sulfur batteries with sulfurized polyacrylonitrile cathodes Angew. Chem. Int. Ed. 2020 59 10732 45

[21] Doan T. N. L.,Ghaznavi M.,Zhao Y..et al. Binding mechanism of sulfur and dehydrogenated polyacrylonitrile in sulfur/polymer composite cathode J. Power Sources 2013 241 61 9

[22] Zhang Y.,Zhao Y.,Yermukhambetova A.,Bakenov Z.,Chen P.. Ternary sulfur/polyacrylonitrile/Mg_0.6Ni_0.4O composite cathodes for high performance lithium/sulfur batteries J. Mater. Chem. A 2013 1 295 301

[23] Fang L.,Xu W.,Lyu X..et al. Suppressing the shuttle effects with FeCo/SPAN cathodes and high-concentration electrolytes for high-performance lithium-sulfur Batteries ACS Appl. Energy Mater. 2023 6 795 801

[24] He R.,Li Y.,Wei S..et al. Construction of high-performance sulfurized poly(acrylonitrile) cathodes for lithium-sulfur batteries via catalytic and conductive regulation J. Alloys Compd. 2022 919 165838

[25] Wu S.,Wang W.,Shan J..et al. Conductive 1T-VS₂-MXene heterostructured bidirectional electrocatalyst enabling compact Li-S batteries with high volumetric and areal capacity Energy Storage Mater. 2022 49 153 63

[26] Wang N.,Chen B.,Qin K..et al. Octopus-inspired design of apical NiS₂ nanoparticles supported on hierarchical carbon composites as an efficient host for lithium sulfur batteries with high sulfur loading ACS Appl. Mater. Interfaces 2020 12 17528 37

[27] Li Z.,Sami I.,Yang J.,Li J.,Kumar R. V.,Chhowalla M.. Lithiated metallic molybdenum disulfide nanosheets for high-performance lithium-sulfur batteries Nat. Energy 2023 8 84 93

[28] Li D.,Li Y.,Xu C.,Zhao S.,Zhang Y.,Huo P.. Enhanced polysulfide adsorption and conversion on FeS₂@CNF-modified separator for Li-S batteries New J. Chem. 2026 50 2891 5

[29] Li Y.,He R.,Liu H..et al. Construction of CoS₂ reduction accelerator-modified sulfurized polyacrylonitrile nanofibers as high-performance cathode materials for practical lithium-sulfur batteries ACS Appl. Energy Mater. 2023 6 8466 78

[30] Liu Y.,Wang W.,Wang A.,Jin Z.,Zhao H.,Yang Y.. A polysulfide reduction accelerator - NiS₂-modified sulfurized polyacrylonitrile as a high performance cathode material for lithium-sulfur batteries J. Mater. Chem. A 2017 5 22120 4

[31] Yang W.,Zhao H.,Chen L..et al. Ferrous sulfide-assisted hollow carbon spheres as sulfur host for advanced lithium-sulfur batteries Chem. Eng. J. 2017 326 1040 7

[32] Lu X.,Zhang Q.,Wang J..et al. High performance bimetal sulfides for lithium-sulfur batteries Chem. Eng. J. 2019 358 955 61

[33] Ren X.,Wang Q.,Pu Y.,Sun Q.,Sun W.,Lu L.. Synergizing spatial confinement and dual-metal catalysis to boost sulfur kinetics in lithium-sulfur batteries Adv. Mater. 2023 35 e2304120

[34] Dong H.,Ji Y.,Wang L..et al. Bimetallic coupling strategy modulating electronic construction to accelerate sulfur redox reaction kinetics for high-energy flexible Li-S batteries Small 2024 20 e2406565

[35] Li N.,Meng T.,Ma L..et al. Curtailing carbon usage with addition of functionalized NiFe₂O₄ quantum dots: toward more practical S cathodes for Li-S cells NanoMicro. Lett. 2020 12 145

[36] Wang Z.,Song C.,Shen H.,Ma S.,Li G.,Li Y.. RuO_x quantum dots loaded on graphdiyne for high-performance lithium-sulfur batteries Adv. Mater. 2024 36 e2307786

[37] Xu Z. L.,Lin S.,Onofrio N..et al. Exceptional catalytic effects of black phosphorus quantum dots in shuttling-free lithium sulfur batteries Nat. Commun. 2018 9 4164

[38] Kresse G.,Furthmüller J.. Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set Comput. Mater. Sci. 1996 6 15 50

[39] Kresse G.,Furthmüller J.. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set Phys. Rev. B. 1996 54 11169

[40] Kresse G.,Joubert D.. From ultrasoft pseudopotentials to the projector augmented-wave method Phys. Rev. B. 1999 59 1758

[41] Perdew J. P.,Burke K.,Ernzerhof M.. Generalized gradient approximation made simple [Phys. Rev. Lett. 77, 3865 (1996)] Phys. Rev. Lett. 1997 78 1396

[42] Babu B.,Koutavarapu R.,Shim J.,Kim J.,Yoo K.. Improved sunlight-driven photocatalytic abatement of tetracycline and photoelectrocatalytic water oxidation by tin oxide quantum dots anchored on nickel ferrite nanoplates J. Electroanal. Chem. 2021 900 115699

[43] Miah M.,Hota P.,Mondal T. K.,Chen R.,Saha S. K.. Mixed metal sulfides (FeNiS₂) nanosheets decorated reduced graphene oxide for efficient electrode materials for supercapacitors J. Alloys Compd. 2023 933 167648

[44] Liu H.,Zhang Y.,Li Y.,Han N.,Liu H.,Zhang X.. Solid-state transformations of active materials in the pores of sulfurized-polyacrylonitrile fiber membranes via nucleophilic reactions for high-loading and free-standing lithium-sulfur battery cathodes Adv. Fiber Mater. 2024 6 772 85

[45] Hwang T. H.,Jung D. S.,Kim J. S.,Kim B. G.,Choi J. W.. One-dimensional carbon-sulfur composite fibers for Na-S rechargeable batteries operating at room temperature Nano Lett. 2013 13 4532 8

[46] Wang X.,Qian Y.,Wang L..et al. Sulfurized polyacrylonitrile cathodes with high compatibility in both ether and carbonate electrolytes for ultrastable lithium-sulfur batteries Adv. Funct. Mater. 2019 29 1902929

[47] Chen X.,Peng L.,Wang L..et al. Ether-compatible sulfurized polyacrylonitrile cathode with excellent performance enabled by fast kinetics via selenium doping Nat. Commun. 2019 10 1021

[48] Lu J.,Zhang Y.,Huang J..et al. Melamine foam-derived N-doped carbon framework and graphene-supported sulfurized polyacrylonitrile for high performance lithiumsulfur battery cathode J. Energy Storage 2025 118 116330

[49] Abdul Razzaq A.,Chen G.,Zhao X..et al. Cobalt coordination with pyridines in sulfurized polyacrylonitrile cathodes to form conductive pathways and catalytic M-N₄S sites for accelerated Li-S kinetics J. Energy Chem. 2021 61 170 8

[50] Lu J.,Zhang Y.,Huang J..et al. A free-standing sulfide polyacrylonitrile/reduced graphene oxide film cathode with nacre-like architecture for high-performance lithium-sulfur batteries J. Power Sources 2025 629 235916

[51] Shao J.,Huang C.,Zhu Q..et al. Flexible CNT-interpenetrating hierarchically porous sulfurized polyacrylonitrile (CIHP-SPAN) electrodes for high-rate lithium-sulfur (Li-S) batteries Nanomaterials. 2024 14 1155

[52] Hao C.,Liu J.,Wang Q..et al. High volumetric capacity FeS₂/SPAN composite with promoted kinetics for Li-S battery ACS Nano 2025 19 25385 94

[53] Wang K.,Guan Y.,Jin Z.,Wang W.,Wang A.. Te_0.045S_0.955PAN composite with high average discharge voltage for Li-S battery J. Energy Chem. 2019 39 249 55

[54] Haridas A. K.,Heo J.,Li X..et al. A flexible and free-standing FeS/sulfurized polyacrylonitrile hybrid anode material for high-rate sodium-ion storage Chem. Eng. J. 2020 385 123453

[55] Liu H.,Xu Q.,Zhang Y.,Han N.,Liu H.,Zhang X.. Multifunctional heterostructure CoS₂/FeS₂ catalysts for enhancing high-performance lithium-sulfurized polyacrylonitrile batteries through intrinsic electric fields Chin. Chem. Lett. 2025 111084

[56] Wang J.,Du Z.,Lv G..et al. Enhancing the backbone regularity of sulfurized polyacrylonitrile for long-life Li-SPAN batteries J. Mater. Chem. A. 2025 13 21545 54

[57] Gao G.,Zheng F.,Pan F.,Wang L. W.. Theoretical investigation of 2D conductive microporous coordination polymers as Li-S battery cathode with ultrahigh energy density Adv. Energy Mater. 2018 8 1801823

[58] Zhao B.,Ren Z.,Tan G.,Li Z.,Xie J.. Defects on Li₂S@graphene cathode improves the performance of lithium-sulfur battery, A theoretical study Acta Mater. 2022 226 117632