提高 Na3–xKxZr2Si2PO12 固体电解质的室温离子电导率：钾取代的影响,Inorganic Chemistry

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提高 Na3–xKxZr2Si2PO12 固体电解质的室温离子电导率：钾取代的影响
Inorganic Chemistry ( IF 4.3 ) Pub Date : 2021-07-19 , DOI: 10.1021/acs.inorgchem.1c01118
Eunseok Heo ₁ , Ji Eun Wang ₂ , Jong Hyuk Yun ₁ , Joo-Hyung Kim ₃ , Dong Jun Kim ₂ , Do Kyung Kim ₁

Affiliation

电池安全性和成本仍然是开发下一代可充电电池的主要挑战。全固态钠（Na）离子电池通过使用丰富的资源和固体电解质，是低成本且安全的可充电电池的一种有前途的选择。然而，由于固体电解质的低离子电导率，固态电池的运行受到限制。因此，开发在室温下具有高离子电导率和化学稳定性的新化合物至关重要。在此，我们报道了一种钾取代钠超离子导体固体电解质，Na _{3– x} K _x Zr ₂ Si ₂ PO ₁₂ (0 ≤ x≤ 0.2)，在室温下表现出 7.734 × 10 ^–4 S/cm ^–1的离子电导率，是未掺杂样品的 2 倍以上。采用 Rietveld 精修的同步加速器粉末衍射图表明，大 K 离子的取代导致晶胞体积增加，Na 扩散通道加宽，Na-Na 距离缩短。我们的工作表明，在 Na 位点上取代较大的阳离子可以有效地拓宽离子扩散通道，从而增加体离子电导率。我们的发现将有助于提高固体电解质的离子电导率，并进一步开发安全的下一代可充电电池。

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Improving Room Temperature Ionic Conductivity of Na3–xKxZr2Si2PO12 Solid-Electrolytes: Effects of Potassium Substitution

The battery safety and cost remain major challenges for developing next-generation rechargeable batteries. All-solid-state sodium (Na)-ion batteries are a promising option for low-cost as well as safe rechargeable batteries by using abundant resources and solid electrolytes. However, the operation of solid-state batteries is limited due to the low ionic conductivity of solid electrolytes. Therefore, it is essential to develop new compounds that feature a high ionic conductivity and chemical stability at room temperature. Herein, we report a potassium-substituted sodium superionic conductor solid electrolyte, Na_3–xK_xZr₂Si₂PO₁₂ (0 ≤ x ≤ 0.2), that exhibits an ionic conductivity of 7.734 × 10^–4 S/cm^–1 at room temperature, which is more than 2 times higher than that of the undoped sample. The synchrotron powder diffraction patterns with Rietveld refinements revealed that the substitution of large K-ions resulted in an increased unit cell volume, widened the Na diffusion channel, and shortened the Na–Na distance. Our work demonstrates that substituting a larger cation on the Na site effectively widens the ion diffusion channel and consequently increases the bulk ionic conductivity. Our findings will contribute to improving the ionic conductivity of the solid electrolytes and further developing safe next-generation rechargeable batteries.

更新日期：2021-08-03

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