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Sustained Lithium Nitrate Release in Gel Polymer Electrolytes Enabled by Bulk Reservoir

  • Xinyue Zhao 1,†,   
  • Yu Zhao 2,†,   
  • Kanghou Ma 1,   
  • Jingyi Han 1,   
  • Ningning Wu 3,*,   
  • Yaohui Zhang 1,*

Received: 30 Apr 2026 | Revised: 06 Aug 2026 | Accepted: 01 Sep 2026 | Published: 04 Sep 2026

Abstract

In ester-based gel polymer electrolytes (GPEs), lithium nitrate (LiNO3) is limited by low solubility and fast depletion. As a result, stable interfacial protection on lithium metal anodes cannot be maintained for long. In this work, a conventional PVDF-based GPE with bulk LiNO3 incorporation (C-LiNO3 GPE) is proposed. A surface-loaded system (S-LiNO3 GPE) is also constructed for comparison. The effect of the LiNO3 location on its release behavior and interfacial evolution is then examined. According to ion chromatography (IC), time-of-flight secondary ion mass spectrometry (TOF-SIMS), and theoretical calculations, different behaviors are observed. For the surface-loaded system, LiNO3 mainly works at the early stage of cycling. The improvement is not sustained. In contrast, when LiNO3 is distributed in the bulk, NO3− is released continuously. This is attributed to the ion-dipole interaction and van der Waals forces between LiNO3 and the poly(vinylidene fluoride) (PVDF) chains. A more uniform solid electrolyte interphase (SEI) is thus formed. It is rich in LiNxOy and Li3N. Because of this, battery reversibility is improved. Cycling stability is also enhanced. At 30 °C, the C-LiNO3 GPE shows an ionic conductivity of 1.11 × 10−3 S cm−1. The Li+ transference number (TLi+) reaches 0.62. For the NCM811 full cell, a discharge capacity of 154.72 mAh g−1 is still retained after 450 cycles at 1 C. These results confirm that building a bulk LiNO3 reservoir in ester-based GPEs is an effective strategy. It enables sustained interfacial protection and improves long-term cycling stability.

References 

  • 1.

    Zhang, W.K.; Yang, X.G.; Wang, C.Y. Thermal-Materials Synergy for Fast-Charging Lithium-Ion Batteries. ACS Energy Lett. 2025, 10, 4995–5002. https://doi.org/10.1021/acsenergylett.5c02528.

  • 2.

    Li, A.M.; Borodin, O.; Pollard, T.P.; et al. Methylation enables the use of fluorine-free ether electrolytes in high-voltage lithium metal batteries. Nat. Chem. 2024, 16, 922–929. https://doi.org/10.1038/s41557-024-01497-x.

  • 3.

    Oh, J.; Frank, J.L.; Leising, R.A.; et al. A repulsive anode interface for high-energy and safe lithium metal batteries. Energy Environ. Sci. 2025, 18, 7504–7513. https://doi.org/10.1039/d5ee01490e.

  • 4.

    Southern, S.L.S.; Cottom, J.; Fritzke, J.B.; et al. Sustainable Carbon Fibers Enable Stable Long‐Term Lithium Metal Deposition for Prospective Zero‐Excess Lithium Metal Batteries. Adv. Energy Mater. 2026, 16, e06780. https://doi.org/10.1002/aenm.202506780.

  • 5.

    Ai, Q.; Zhang, B.; Liu, X.; et al. Strong and brittle lithium dendrites. Science 2026, 391, 1125–1129. https://doi.org/10.1126/science.adu9988.

  • 6.

    Nahm, S.; Kim, H.; Kim, M.; et al. Revealing the mechanisms behind transient whisker suppression by LiNO3 in anode-free lithium metal batteries. J. Energy Chem. 2026, 114, 485–495. https://doi.org/10.1016/j.jechem.2025.10.037.

  • 7.

    Liu, S.; Xu, C.; Che, S.; et al. Dual-descriptor-guided design of an electric field-sensitive solubilizing additive for stable lithium metal batteries. Energy Environ. Sci. 2026, 19, 2644–2657. https://doi.org/10.1039/d6ee00038j.

  • 8.

    Chen, D.; Zhang, Z.; Wang, J.; et al. Solvent-coordination-regulated gel polymer electrolyte for stable high-voltage lithium metal batteries. eScience 2026. 100568. https://doi.org/10.1016/j.esci.2026.100568.

  • 9.

    Jabbari, V.; Yurkiv, V.; Rasul, M.G.; et al. An efficient gel polymer electrolyte for dendrite-free and long cycle life lithium metal batteries. Energy Storage Mater. 2022, 46, 352–365. https://doi.org/10.1016/j.ensm.2022.01.031.

  • 10.

    Zhao, X.; Ma, K.; Zhao, Y.; et al. Research on the Mechanism of Space Charge Layer in Gel Electrolyte: Synergistic Effects of PFPE Networks and Li2O. Adv. Funct. Mater. 2025, 35, 2424160. https://doi.org/10.1002/adfm.202424160.

  • 11.

    Duong, H.T.; Hoang, T.M.; Pham, D.T.; et al. Enhancing Solid-State Polymer Lithium Battery Performance with Commercial-Grade TiO2 Additives: Toward Industrial-Scale Applications. Mater. Chem. Phys. 2026, 348, 131662. https://doi.org/10.1016/j.matchemphys.2025.131662.

  • 12.

    Wu, P.; Zeng, Q.; Liu, X.; et al. Synergistic preparation of high-performance composite blast furnace slag powder from multiple industrial solid wastes: Performance regulation and optimization. Constr. Build. Mater. 2024, 411, 134231. https://doi.org/10.1016/j.conbuildmat.2023.134231.

  • 13.

    Deng, L.; You, L.; Wang, M.; et al. Study on the electrochemical performance of a high ionic conductivity composite gel polymer electrolyte for lithium-ion batteries. Chem. Eng. J. 2025, 507, 160694. https://doi.org/10.1016/j.cej.2025.160694.

  • 14.

    Yang, H.; Yan, J.; Gao, S.; et al. An asymmetric functional gel polymer electrolyte enables superior interfacial compatibility for wide temperature lithium metal batteries. Energy Environ. Sci. 2025, 18, 9854–9864. https://doi.org/10.1039/d5ee03838c.

  • 15.

    Wu, Z.Y.; Li, S.F.; Huang, Y.F. Stabilizing poly(vinylidene fluoride) solid-state electrolytes/lithium metal interface by constructing an ultrathin interface layer to inhibit the electron transfer. Energy Storage Mater. 2024, 68, 103330. https://doi.org/10.1016/j.ensm.2024.103330.

  • 16.

    Yang, L.; Chen, L.; Song, C.; et al. A Natural Clay LiNO3 Solubilizer for Stabilizing Lithium Metal Batteries. ACS Nano 2026, 20, 11374–11385. https://doi.org/10.1021/acsnano.6c01170.

  • 17.

    Zhang, X.Q.; Chen, X.; Hou, L.P.; et al. Regulating anions in the solvation sheath of lithium ions for stable lithium metal batteries. ACS Energy Lett. 2019, 4, 411–416. https://doi.org/10.1021/acsenergylett.8b02376.

  • 18.

    Liu, Y.; Lin, D.; Li, Y.; et al. Solubility-mediated sustained release enabling nitrate additive in carbonate electrolytes for stable lithium metal anode. Nat. Commun. 2018, 9, 3656. https://doi.org/10.1038/s41467-018-06077-5.

  • 19.

    Stuckenberg, S.; Bela, M.M.; Lechtenfeld, C.T.; et al. Influence of LiNO3 on the Lithium Metal Deposition Behavior in Carbonate‐Based Liquid Electrolytes and on the Electrochemical Performance in Zero‐Excess Lithium Metal Batteries. Small 2024, 20, 2305203. https://doi.org/10.1002/smll.202305203.

  • 20.

    Haidar, A.H.; Hawari, N.H.; Anggreini, D.; et al. PVDF Nanofiber Separator with Sustained LiNO3 Additive Release for Dendrite-Suppressed Anode-Free Lithium Metal Batteries. J. Mater. Chem. A 2026, 14, 12449–12460. https://doi.org/10.1039/d5ta09302c.

  • 21.

    Holmboe, M.; Larsson, P.; Anwar, J.; et al. Partitioning into colloidal structures of fasted state intestinal fluid studied by molecular dynamics simulations. Langmuir 2016, 32, 12732–12740. https://doi.org/10.1021/acs.langmuir.6b03008.

  • 22.

    Hess, B.; Kutzner, C.; van der Spoel, D.; et al. GROMACS 4: Algorithms for Highly Efficient, Load-Balanced, and Scalable Molecular Simulation. J. Chem. Theory Comput. 2008, 4, 435–447. https://doi.org/10.1021/ct700301q.

  • 23.

    Adamo, C.; Barone, V. Toward reliable density functional methods without adjustable parameters: The PBE0 model. J. Chem. Phys. 1999, 110, 6158–6170. https://doi.org/10.1063/1.478522.

  • 24.

    Grimme, S.; Ehrlich, S.; Goerigk, L. Effect of the Damping Function in Dispersion Corrected Density Functional Theory. J. Comput. Chem. 2011, 32, 1456–1465. https://doi.org/10.1002/jcc.21759.

  • 25.

    Duan, H.; You, Y.; Wang, G.; et al. Lithium-ion charged polymer channels flattening lithium metal anode. Nano-Micro Lett. 2024, 16, 78. https://doi.org/10.1007/s40820-023-01300-5.

  • 26.

    Zhang, D.; Tian, T.; Guo, Y.; et al. Interface‐Compatible Deep Eutectic Polymer Electrolytes for High‐Voltage Solid‐State Lithium Metal Batteries. Adv. Funct. Mater. 2026, 36, e24041. https://doi.org/10.1002/adfm.202524041.

  • 27.

    Zhang, C.; Zhao, L.; Li, F.; et al. Optimizing the Electron Density of PVDF‐HFP‐Based Solid Polymer Electrolyte by Donor–Acceptor COF Toward High‐Performance Solid‐State Lithium Metal Batteries. Adv. Mater. 2025, 37, e13427. https://doi.org/10.1002/adma.202513427.

  • 28.

    Yang, Z.; Ye, Y.; Meng, N.; et al. Adaptive 3D Cross-Linked Single-Ion Conducting Polymer Electrolytes Enable Powerful Interface for Solid State Batteries. Angew. Chem.-Int. Ed. 2025, 64, e202505232. https://doi.org/10.1002/anie.202505232.

  • 29.

    Mireja, S.; Khakhar, D.V. Methods to characterize the crystal polymorphs of polyvinylidene fluoride using Fourier transform infrared spectroscopy. Polym. Eng. Sci. 2023, 63, 2857–2870. https://doi.org/10.1002/pen.26410.

  • 30.

    Mishra, R.; Singh, S.K.; Gupta, H.; et al. Polar β-phase PVDF-HFP-based freestanding and flexible gel polymer electrolyte for better cycling stability in a Na battery. Energy Fuels 2021, 35, 15153–15165. https://doi.org/10.1021/acs.energyfuels.1c02114.

  • 31.

    Cao, Y.; Kang, G.; Duan, J.; et al. LiNO3 Nanoparticle Enabled Solvent Confinement and a Favorable Li+ Solvation Environment in Ester Electrolytes for Anode-Free Lithium Metal Batteries. ACS Nano 2025, 19, 34745–34756. https://doi.org/10.1021/acsnano.5c09514.

  • 32.

    Xue, L.; Pan, H.; Wang, Y.; et al. Polarity-Matched Perfluorinated Gel Electrolytes toward Safe Sodium-Ion Batteries. ACS Energy Lett. 2026, 11, 1780–1790. https://doi.org/10.1021/acsenergylett.5c03404.

  • 33.

    Wang, H.; Yang, J.; Xu, X.; et al. Competitive ion coordination in gel polymer electrolytes enables decoupling of mechanical strength and ionic conductivity. Adv. Mater. 2025, 37, e04625. https://doi.org/10.1002/adma.202504625.

  • 34.

    Zhou, M.; Cui, K.; Wang, T.S.; et al. Bimetal Fluorides with Adjustable Vacancy Concentration Reinforcing Ion Transport in Poly(ethylene oxide) Electrolyte. ACS Nano 2024, 18, 26986–26996. https://doi.org/10.1021/acsnano.4c09176.

  • 35.

    Lu, Y.; Liu, Y.; Zhang, S.; et al. Toward practical lithium metal batteries via a solvation structure regulation strategy in in situ polymerized fluorinated gel polymer electrolytes. Energy Environ. Sci. 2025, 18, 9512–9523. https://doi.org/10.1039/d5ee03662c.

  • 36.

    Zhou, Y.; Liu, W.; Tan, B.; et al. Crystallinity and β Phase Fraction of PVDF in Biaxially Stretched PVDF/PMMA Films. Polymers 2021, 13, 998. https://doi.org/10.3390/polym13070998.

  • 37.

    Yuan, S.; Cao, Z.; Zhao, Z.; et al. An Unchoked High-Entropy Composite Electrolyte With Li+-Bond Enabled Tough-and-Adhesive Nano-Interpenetrating Network. Adv. Funct. Mater. 2025, 35, 2503663. https://doi.org/10.1002/adfm.202503663.

  • 38.

    Srout, M.; Carboni, M.; Gonzalez, J.A.; et al. Insights into the importance of native passivation layer and interface reactivity of metallic lithium by electrochemical impedance spectroscopy. Small 2023, 19, 2206252. https://doi.org/10.1002/smll.202206252.

  • 39.

    Shi, Z.; Fang, M.; Zhang, J.; et al. A persistent-range hydrogen-bonded gel polymer electrolyte enabling wide-temperature and recyclable lithium metal batteries. Sci. Adv. 2026, 12, eadz1014. https://doi.org/10.1126/sciadv.adz1014.

  • 40.

    Xu, W.; Zhou, L.; Lu, S.; et al. Fluorine-free gel polymer electrolyte for lithium oxide-rich solid electrolyte interphase and stable Li metal batteries. Nat. Commun. 2025, 16, 9308. https://doi.org/10.1038/s41467-025-64345-7.

  • 41.

    Zhang, S.; Liu, H.; Liu, Z.; et al. Non‐resonant structure induces n‐rich solid electrolyte interface toward ultra‐stable solid‐state lithium‐metal batteries. Adv. Funct. Mater. 2024, 34, 2401377. https://doi.org/10.1002/adfm.202401377.

  • 42.

    Wang, C.; Deng, T.; Fan, X.; et al. Identifying soft breakdown in all-solid-state lithium battery. Joule 2022, 6, 1770–1781. https://doi.org/10.1016/j.joule.2022.05.020.

  • 43.

    Miao, X.; Wu, Z.; Hu, W.; et al. Dual‐Aspect Control of Lithium Nucleation and Growth With Hydroxyapatite and Liquid Crystal Polymers for High‐Performance Lithium Metal Batteries. Adv. Energy Mater. 2025, 15, 2500566. https://doi.org/10.1002/aenm.202500566.

  • 44.

    Zhao, Y.; Shi, J.; Yang, H.; et al. Catalyzing Li-Salt Dissociation and Decomposition for a Conformal Low-Impedance Solid Electrolyte Interphase in Solid-State Li Metal Batteries. J. Am. Chem. Soc. 2026, 148, 11540–11550. https://doi.org/10.1021/jacs.5c16750.

  • 45.

    Zhang, S.; Li, Y.; Bannenberg, L.J.; et al. The lasting impact of formation cycling on the Li-ion kinetics between SEI and the Li-metal anode and its correlation with efficiency. Sci. Adv. 2024, 10, eadj8889. https://doi.org/10.1126/sciadv.adj8889.

  • 46.

    Maradesa, A.; Py, B.; Huang, J.; et al. Advancing electrochemical impedance analysis through innovations in the distribution of relaxation times method. Joule 2024, 8, 1958–1981. https://doi.org/10.1016/j.joule.2024.05.008.

  • 47.

    Cui, F.; Zhan, X.; Luo, Y.; et al. Unveiling performance limitations in all-solid-state Na-O2 batteries through EIS-DRT analysis. Cell Rep. Phys. Sci. 2025, 6, 102787. https://doi.org/10.1016/j.xcrp.2025.102787.

  • 48.

    Li, P.; Zhao, Z.; Fei, Y.; et al. LiNO3‐Based Electrolyte with Fast Kinetics for Lithium Metal Batteries Under Practical Conditions. Adv. Energy Mater. 2025, 15, 2500882. https://doi.org/10.1002/aenm.202500882.

  • 49.

    Liu, Q.; Xu, Y.; Wang, J.; et al. Sustained-release nanocapsules enable long-lasting stabilization of Li anode for practical Li-metal batteries. Nano-Micro Lett. 2020, 12, 176. https://doi.org/10.1007/s40820-020-00514-1.

  • 50.

    Liu, Y.; Qin, X.; Zhou, D.; et al. A biscuit-like separator enabling high performance lithium batteries by continuous and protected releasing of NO3− in carbonate electrolyte. Energy Storage Mater. 2020, 24, 229–236. https://doi.org/10.1016/j.ensm.2019.08.016.

  • 51.

    Li, S.; Liu, Y.; Wang, K.; et al. Sustainable release of LiNO3 in carbonate electrolytes for stable lithium metal anodes. Chem. Commun. 2024, 60, 2649–2652. https://doi.org/10.1039/d3cc05859j.

  • 52.

    Shi, Q.; Zhong, Y.; Wu, M.; et al. High-capacity rechargeable batteries based on deeply cyclable lithium metal anodes. Proc. Natl. Acad. Sci. USA 2018, 115, 5676–5680. https://doi.org/10.1073/pnas.1803634115.

  • 53.

    Yim, T.; Kim, K.; Hassig, M.Q.; et al. Lithium-Nitrate-Containing Gel Polymer Electrolyte for Carbonate-Based Anode-Free Lithium Metal Batteries. ACS Appl. Mater. Interfaces 2025, 17, 37851–37862. https://doi.org/10.1021/acsami.5c03252.

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DOI
10.53941/echem.2026.100011
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Volume 2, Issue 2
How to Cite
Zhao, X.; Zhao, Y.; Ma, K.; Han, J.; Wu, N.; Zhang, Y. Sustained Lithium Nitrate Release in Gel Polymer Electrolytes Enabled by Bulk Reservoir. eChem 2026, 2 (2), 11. https://doi.org/10.53941/echem.2026.100011.
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