High energy density all-solid-state lithium metal batteries (ASSLMBs) with flexible, low-cost solid polymer electrolytes (SPEs) have received extensive research attention, but the low ionic conductivity of SPEs and the rapid growth of lithium dendrite seriously limit their performance. Here, polyethylene oxide (PEO) based solid polymer electrolytes (SPEs) containing potassium hexafluorophosphate (KPF₆) salt additive are developed for lithium dendrite-free ASSLMBs. The results show that with the additive of KPF₆, the dissociation of lithium salt is promoted, providing more free Li⁺ ions in SPEs and enhancing the ionic conductivity. KPF₆ additive also makes SPE more flexible and promotes the formation of Li₂S and LiF-rich solid electrolyte interphase (SEI). Besides, the presence of K⁺ is also expected to work as a shield to inhibit the lithium dendrite growth. With the synergistic effect of above advantages, lithium dendrite growth and interfacial side-reactions in ASSLMBs are prevented. Li/Li symmetric cell with SPE can achieve a stable cycling performance over 1500 h with low polarization potential. The all-solid-state LiFePO₄/Li cell releases an initial capacity of 142.1 mAh g⁻¹ with a capacity retention of 91.3% after 200 cycles at 0.5 C and 60 °C. This study provides a facile scheme for designing high performance ASSLMBs.

具有柔性、低成本固体聚合物电解质（SPEs）的高能量密度全固态锂金属电池（ASSLMBs）受到了广泛的研究关注，但SPEs的低离子电导率和锂枝晶的快速生长严重限制了其性能. _{在这里，开发了含有六氟磷酸钾 (KPF 6} ) 盐添加剂的基于聚环氧乙烷 (PEO) 的固体聚合物电解质 (SPE)，用于无锂枝晶的 ASSLMB。结果表明，KPF ₆添加剂促进了锂盐的解离，在SPEs中提供了更多的游离Li ⁺离子，提高了离子电导率。KPF ₆添加剂还使 SPE 更加柔韧并促进 Li _2的形成富含 S 和 LiF 的固体电解质界面 (SEI)。此外，K ⁺的存在也有望起到抑制锂枝晶生长的屏蔽作用。借助上述优势的协同作用，防止了 ASSLMB 中的锂枝晶生长和界面副反应。具有 SPE 的 Li/Li 对称电池可以在 1500 小时以上以低极化电位实现稳定的循环性能。全固态LiFePO ₄ /Li电池在0.5℃和60℃循环200次后，初始容量为142.1 mAh g ^{-1 ，容量保持率为91.3%。}本研究为设计高性能 ASSLMB 提供了一种简便的方案。