Abstract Divalent Ni2+ cation-conducting solid electrolytes, (NixHf1−x)4/(4−2x)Nb(PO4)3, were successfully developed by introducing Ni2+ cations into a HfNb(PO4)3 solid exhibiting a three-dimensional NASICON-type structure. Although the HfNb(PO4)3 solid has been reported to be purely a Hf4+ ion conductor, the conducting species was changed to the divalent Ni2+ cation upon Ni2+ doping, due to the facile migration of lower-valence ions in the rigid crystal lattice. In addition, by selecting the well-ordered NASICON-type structure as the mother crystal, the (NixHf1−x)4/(4−2x)Nb(PO4)3 solid electrolytes exhibited lower activation energies and higher Ni2+ cation conductivities than a previously reported NiZr4(PO4)6 solid with the β-Fe2(SO4)3-type structure. Among the (NixHf1−x)4/(4−2x)Nb(PO4)3 solids, (Ni0.06Hf0.94)4/3.88Nb(PO4)3 (x = 0.06) showed the highest Ni2+ ion conductivity, of 2.27 × 10−4 S·cm−1 at 600 °C, which is ca. 23 times higher than that of the NiZr4(PO4)6 solid.

中文翻译：

---

NASICON 型固体中的二价 Ni2+ 阳离子传导

摘要 通过将 Ni2+ 阳离子引入呈现三维 NASICON 型的 HfNb(PO4)3 固体中，成功开发出二价 Ni2+ 阳离子导电固体电解质 (NixHf1−x)4/(4−2x)Nb(PO4)3结构体。尽管据报道 HfNb(PO4)3 固体纯粹是 Hf4+ 离子导体，但由于低价离子在刚性晶格中容易迁移，导电物质在 Ni2+ 掺杂后变为二价 Ni2+ 阳离子。此外，通过选择有序的 NASICON 型结构作为母晶，(NixHf1-x)4/(4-2x)Nb(PO4)3 固体电解质表现出比以前更低的活化能和更高的 Ni2+ 阳离子电导率。报道了具有 β-Fe2(SO4)3 型结构的 NiZr4(PO4)6 固体。在 (NixHf1-x)4/(4-2x)Nb(PO4)3 固体中，(Ni0.06Hf0.94)4/3.88Nb(PO4)3 (x = 0。06) 显示出最高的 Ni2+ 离子电导率，在 600 °C 时为 2.27 × 10−4 S·cm−1，约为 比 NiZr4(PO4)6 固体高 23 倍。