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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.

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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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