Residual solvents in vinylidene fluoride (VDF)-based solid polymer electrolytes (SPEs) have been recognized as responsible for their high ionic conductivity. However, side reactions by the residual solvents with the lithium (Li) metal induce poor stability, which has been long neglected. This study proposes a strategy to achieve a delicate equilibrium between ion conduction and electrode stability for VDF-based SPEs. Specifically, 2,2,2-trifluoro-N,N-dimethylacetamide (FDMA) is developed as the nonside reaction solvent for poly(vinylidene fluoride-co-hexafluoropropylene) (PVHF)-based SPEs, achieving both high ionic conductivity and significantly improved electrochemical stability. The developed FDMA solvent fosters the formation of a stable solid electrolyte interphase (SEI) through interface reactions with Li metal, effectively mitigating side reactions and dendrite growth on the Li metal electrode. Consequently, the Li||Li symmetric cells and Li||LiFePO₄ cells demonstrate excellent cycling performance, even under limited Li (20 µm thick) supply and high-loading cathodes (>10 mg cm⁻², capacity >1 mAh cm⁻²) conditions. The stable Li||LiCoO₂ cells operation with a cutoff voltage of 4.48 V indicates the high-voltage stability of the developed SPE. This study offers valuable insights into the development of advanced VDF-based SPEs for enhanced lithium metal battery performance and longevity.

中文翻译：

---

抑制偏二氟乙烯聚合物电解质中残留溶剂引起的副反应，实现超稳定固态锂金属电池


基于偏二氟乙烯 (VDF) 的固体聚合物电解质 (SPE) 中的残留溶剂被认为是其高离子电导率的原因。然而，残留溶剂与锂（Li）金属的副反应导致稳定性差，这一点长期以来一直被忽视。本研究提出了一种策略，可在基于 VDF 的 SPE 中实现离子传导和电极稳定性之间的微妙平衡。具体而言，2,2,2-三氟-N,N-二甲基乙酰胺（FDMA）被开发为聚（偏二氟乙烯-六氟丙烯）（PVHF）基SPE的非副反应溶剂，既实现了高离子电导率，又显着提高了电化学稳定性。开发的FDMA溶剂通过与锂金属的界面反应促进稳定的固体电解质界面（SEI）的形成，有效减轻副反应和锂金属电极上的枝晶生长。因此，Li||Li 对称电池和 Li||LiFePO ₄ 电池表现出优异的循环性能，即使在有限的 Li（20 µm 厚）供应和高负载阴极（>10 mg cm ⁻² ，容量 >1 mAh cm ⁻² ）条件。 Li||LiCoO ₂ 电池在 4.48 V 截止电压下稳定运行，表明所开发的 SPE 具有高电压稳定性。这项研究为开发先进的基于 VDF 的 SPE 提供了宝贵的见解，以提高锂金属电池的性能和寿命。