Low-cost synthesis of high-purity Li₂S for sulfide solid state electrolytes enabled by polyvinyl alcohol

Abstract

Sulfide solid electrolytes (S-SEs) are widely preferred for their high ionic conductivity and processability. However, the further development of S-SEs is hindered by the excessive price of its critical raw materials of Li₂S. Herein, a low-cost and environmentally friendly method is proposed to synthesize Li₂S by the carbothermal reduction reaction of Li₂SO₄ in one step, and the effects of various factors are also discussed. As a result, a purity of 99.67% is obtained over the self-prepared Li₂S. More importantly, the cost of the self-prepared Li₂S is only about 50 $/kg, which is significantly lower than that of the commercial counterpart (10000–15000 dollar/kg). Moreover, the ionic conductivity of Li_5.5PS_4.5Cl_1.5 prepared using self-prepared Li₂S as raw materials is 4.19 mS/cm at room temperature, which is a little higher than that of Li_5.5PS_4.5Cl_1.5 using commercial Li₂S (4.05 mS/cm). And the all-solid-state lithium batteries (ASSLBs) with the as-prepared electrolytes could maintain a discharge capacity of 109.9 mA·h/g with an average coulombic efficiency (CE) of 98% after 100 cycles at 0.2C, which is equivalent to that using commercial Li₂S, demonstrating that the preparation strategy of Li₂S proposed in this work is feasible.

References

[[1]] Yoon M, Dong Y-h, Huang Y-m, et al.. Eutectic salt-assisted planetary centrifugal deagglomeration for single-crystalline cathode synthesis [J]. Nature Energy, 2023, 8: 482-491.

[[2]] Wang D-z, Wang J-s, Li X-b, et al.. Enhanced prelithiation performance of Li₅FeO₄ cathode additive and optimized solid electrolyte interface enabled by Mn substitution [J]. Journal of Alloys and Compounds, 2024, 992: 174607.

[[3]] Fei H, Liu R-q, Liu T, et al.. Direct seawater electrolysis: From catalyst design to device applications [J]. Advanced Materials, 2024, 36(17): e2309211.

[[4]] Wu C-l, Song J-x, Huang X-r, et al.. A discharging internal resistance dynamic model of lithium-ion batteries based on multiple influencing factors [J]. Journal of Central South University, 2024, 31(2): 670-678.

[[5]] Yang M, Wan L-j, Jin X-qi. Synthesis of ZnGaNO solid solution-carbon nitride intercalation compound composite for improved visible light photocatalytic activity [J]. Journal of Central South University, 2017, 24(2): 276-283.

[[6]] Tian C, Zhao S-h, Feng Y, et al.. Research progress and prospect of silicon nanotubes in new energy field [J]. Journal of Central South University, 2023, 30(7): 2133-2148.

[[7]] Hu H, Wang Y, Huang Y, et al.. Na₂FePO₄F/C composite synthesized via a simple solid state route for lithium-ion batteries [J]. Journal of Central South University, 2019, 26(6): 1521-1529.

[[8]] Wang Z-y, Li C, Huang Y-d, et al.. Fast-ionic conductor Li_2.64(Sc_0.9Ti_0.1)₂(PO4)₃ doped PVDF-HFP hybrid gel-electrolyte for lithium ion batteries [J]. Journal of Central South University, 2022, 29(9): 2980-2990.

[[9]] Tan D H S, Chen Y-t, Yang H-d, et al.. Carbon-free high-loading silicon anodes enabled by sulfide solid electrolytes [J]. Science, 2021, 373(6562): 1494-1499.

[[10]] Li Y-x, Song S-b, Kim H, et al.. A lithium superionic conductor for millimeter-thick battery electrode [J]. Science, 2023, 381(6653): 50-53.

[[11]] Ahuis M, Doose S, Vogt D, et al.. Recycling of solidstate batteries [J]. Nature Energy, 2024, 9: 373-385.

[[12]] Shao S-y, He L, Zhang J-w, et al.. 3, 3′-dithiodipropionic acid as a functional electrolyte additive in lithium-sulfur battery [J]. Journal of Central South University, 2024, 31(2): 431-442.

[[13]] Li X-b, Wang J-s, Han C, et al.. Surface engineering of nickel-rich single-crystal layered oxide cathode enables high-capacity and long cycle-life sulfide all-solid-state batteries [J]. Advanced Powder Materials, 2024, 3(5): 100228.

[[14]] ALBERTUS P, ANANDAN V, BAN Chun-mei, et al. Challenges for and pathways toward Li-metal-based all-solid-state batteries [J]. ACS Energy Letters, 2021: 1399–1404. DOI: https://doi.org/10.1021/acsenergylett.1c00445.

[[15]] Wan F-m, Fang L-r, Zhang X, et al.. Lithium sulfide nanocrystals as cathode materials for advanced batteries [J]. Journal of Energy Chemistry, 2021, 63: 138-169.

[[16]] Zhang Q, Han A, Zhang X, et al.. Green synthesis for battery materials: A case study of making lithium sulfide via metathetic precipitation [J]. ACS Applied Materials & Interfaces, 2023, 15(1): 1358-1366.

[[17]] Wu F-x, Lee J T, Magasinski A, et al.. Solution-based processing of graphene-Li₂S composite cathodes for lithium-ion and lithium-sulfur batteries [J]. Particle & Particle Systems Characterization, 2014, 31(6): 639-644.

[[18]] Chen Y, Lu S-t, Zhou J, et al.. Synergistically assembled Li₂S/FWNTs@Reduced graphene oxide nanobundle forest for free-standing high-performance Li₂S cathodes [J]. Advanced Functional Materials, 2017, 27(25): 1700987.

[[19]] Zhang J, Shi Y, Ding Y, et al.. A conductive molecular framework derived Li₂S/N, P-codoped carbon cathode for advanced lithium-sulfur batteries [J]. Advanced Energy Materials, 2017, 7(14): 1602876.

[[20]] Li Y-j, Wu J-b, Zhang B, et al.. Fast conversion and controlled deposition of lithium (poly) sulfides in lithium-sulfur batteries using high-loading cobalt single atoms [J]. Energy Storage Materials, 2020, 30: 250-259.

[[21]] Chen C-g, Li D-j, Gao L, et al.. Carbon-coated core-shell Li₂S@C nanocomposites as high performance cathode materials for lithium-sulfur batteries [J]. Journal of Materials Chemistry A, 2017, 5(4): 1428-1433.

[[22]] Zhao Y-z, Yang Y-a, Wolden C A. Scalable synthesis of size-controlled Li₂S nanocrystals for next-generation battery technologies [J]. ACS Applied Energy Materials, 2019, 2(3): 2246-2254.

[[23]] Li X, Gao M-x, Du W-b, et al.. A mechanochemical synthesis of submicron-sized Li₂S and a mesoporous Li₂S/C hybrid for high performance lithium/sulfur battery cathodes [J]. Journal of Materials Chemistry A, 2017, 5(14): 6471-6482.

[[24]] Baloch M, Shanmukaraj D, Bondarchuk O, et al.. Variations on Li₃N protective coating using ex-situ and in situ techniques for Li° in sulphur batteries [J]. Energy Storage Materials, 2017, 9: 141-149.

[[25]] Yang S-j, Wan F-m, Han A-g, et al.. Environmentally friendly, non-glove box, closed-system and continuously massive production of lithium sulfide for battery applications [J]. Journal of Cleaner Production, 2023, 382: 135221.

[[26]] Shi J-y, Zhang J, Zhao Y-f, et al.. Synthesis of Li₂S-carbon cathode materials via carbothermic reduction of Li₂SO₄ [J]. Frontiers in Energy Research, 2019, 7: 53.

[[27]] Yang H-l, Lei Y-j, Yang Q-r, et al.. Cobalt-induced highly-electroactive Li₂S heterostructured cathode for Li-S batteries [J]. Electrochimica Acta, 2023, 439: 141652.

[[28]] Wen X-y, Xiang K-x, Zhu Y-r, et al.. 3D hierarchical nitrogen-doped graphene/CNTs microspheres as a sulfur host for high-performance lithium-sulfur batteries [J]. Journal of Alloys and Compounds, 2020, 815: 152350.

[[29]] Yu H, Zeng P, Liu H, et al.. Li₂S in situ grown on three-dimensional porous carbon architecture with electron/ion channels and dual active sites as cathodes of Li-S batteries [J]. ACS Applied Materials & Interfaces, 2021, 13(28): 32968-32977.

[[30]] Colon M, Todolí J L, Hidalgo M, et al.. Development of novel and sensitive methods for the determination of sulfide in aqueous samples by hydrogen sulfide generation-inductively coupled plasma-atomic emission spectroscopy [J]. Analytica Chimica Acta, 2008, 609(2): 160-168.

[[31]] Kohl M, Brückner J, Bauer I, et al.. Synthesis of highly electrochemically active Li₂S nanoparticles for lithium-sulfur-batteries [J]. Journal of Materials Chemistry A, 2015, 3(31): 16307-16312.

[[32]] Nzioka A M, Alunda B O, Yan C-z, et al.. Characterization of carbon fibers recovered through mechanochemical-enhanced recycling of waste carbon fiber reinforced plastics [J]. Journal of Central South University, 2019, 26(10): 2688-2703.

[[33]] Sun J-c, Li Z-f, Ren X, et al.. High volumetric energy density of LiFePO₄/C microspheres based on xylitol-polyvinyl alcohol complex carbon sources [J]. Journal of Alloys and Compounds, 2019, 773: 788-795.

[[34]] Ye F-m, Noh H, Lee J-h, et al.. Li₂S/carbon nanocomposite strips from a low-temperature conversion of Li₂SO₄ as high-performance lithium-sulfur cathodes [J]. Journal of Materials Chemistry A, 2018, 6(15): 6617-6624.

[[35]] Yang H-g, Xu S-b, Jiang L, et al.. Thermal decomposition behavior of poly (vinyl alcohol) with different hydroxyl content [J]. Journal of Macromolecular Science, Part B, 2012, 51(3): 464-480.

[[36]] Diyuk V E, Zaderko A N, Grishchenko L M, et al.. Surface chemistry of fluoroalkylated nanoporous activated carbons: XPS and 19F NMR study [J]. Applied Nanoscience, 2022, 12(3): 637-650.

[[37]] Klein M J, Veith G M, Manthiram A. Chemistry of sputter-deposited lithium sulfide films [J]. Journal of the American Chemical Society, 2017, 139(31): 10669-10676.