Fluoride-ion batteries are promising “next-generation” electrochemical energy storage devices, and thus, the room-temperature rechargeable fluoride-ion batteries (FIBs) have attracted tremendous attention due to their high theoretical volume energy density and high safety. However, a series of problems including high interface impedance and poor ionic conductivity at room temperature prevent further development and commercial application of FIBs. Herein, rare-earth element Eu³⁺-doped BaSnF₄ solid solutions [Ba_1–xEu_xSnF_4+x (0 ≤ x ≤ 0.06)] are designed and prepared to improve the performance of BaSnF₄ solid electrolytes for room-temperature FIBs. It has been found that the as-prepared Ba_0.98Eu_0.02SnF_4.02 solid-state electrolyte can achieve a better ionic conductivity of 3.8 × 10^–4 S cm^–1 at room temperature after a calcination process at 300 °C for 2 h, which is the improvement of an order of magnitude in comparison with the original samples. In addition, the FIBs based on Ba_1–xEu_xSnF_4+x (0 ≤ x ≤ 0.04) solid-state electrolytes (Sn/Ba_0.98Eu_0.02SnF_4.02/BiF₃) show a discharge capacity of 106 mAh g^–1 at 1st cycle and 72 mAh g^–1 at 20th cycle. Moreover, the Sn/Ba_1–xEu_xSnF_4+x/BiF₃ (0 ≤ x ≤ 0.04) batteries also exhibit good cycling stability and rate performance. Therefore, the addition of Eu³⁺ can better improve the ionic conductivity of the original solid electrolyte material, which provides a new strategy for the preparation and modification of fluoride-ion electrolytes in FIBs chracterization chracterization.

中文翻译：

---

用于室温氟离子电池的 Eu3+ 掺杂 BaSnF4 基固态电解质的制备和性能

氟离子电池是有前途的“下一代”电化学储能装置，因此，室温可充电氟离子电池（FIBs）因其高理论体积能量密度和高安全性而引起了极大的关注。然而，室温下界面阻抗高、离子电导率差等一系列问题阻碍了FIBs的进一步发展和商业应用。在此，设计并制备了稀土元素 Eu ³⁺掺杂的 BaSnF ₄固溶体 [Ba _{1– x} Eu _x SnF _{4+ x} (0 ≤ x ≤ 0.06)] 以提高 BaSnF ₄的性能用于室温 FIB 的固体电解质。已经发现，所制备的 Ba _0.98 Eu _0.02 SnF _4.02固态电解质在 300 °C 下煅烧 2 h 后，在室温下可以获得更好的离子电导率，达到 3.8 × 10 ^–4 S cm ^–1，与原始样本相比，这是一个数量级的改进。此外，基于 Ba _{1– x} Eu _x SnF _{4+ x} (0 ≤ x ≤ 0.04) 固态电解质 (Sn/Ba _0.98 Eu _0.02 SnF _4.02 / BiF ₃) 显示第 1 次循环的放电容量为 106 mAh g ^–1，第20 次循环的放电容量为72 mAh g ^–1。此外，Sn/Ba _{1– x} Eu _x SnF _{4+ x} / BiF ₃ (0 ≤ x ≤ 0.04) 电池还表现出良好的循环稳定性和倍率性能。因此，Eu ^{3+ 的加入}可以更好地提高原有固体电解质材料的离子电导率，为FIBs表征表征中氟离子电解质的制备和改性提供了新的策略。