Scholarlink

<p>In this study, we investigated the co-doping of Si<sup>4+</sup> and Co<sup>3+</sup> ions at the P<sup>5+</sup> and Al<sup>3+</sup> sites of the Li<sub>1.3</sub>Al<sub>0.3</sub>Ti<sub>1.7</sub>(PO<sub>4</sub>)<sub>3</sub> electrolyte to enhance Li-ion conductivities. Si<sup>4+</sup> doping increased the maximum relative density of the sintered Li<sub>1.3</sub>Al<sub>0.3</sub>Ti<sub>1.7</sub>(PO<sub>4</sub>)<sub>3</sub> electrolyte, although it slightly raised the densification temperature. The Li<sub>1.35</sub>Al<sub>0.3</sub>Ti<sub>1.7</sub>P<sub>2.95</sub>Si<sub>0.05</sub>O<sub>12</sub> electrolyte achieved 96.1% theoretical density at 925&#xa0;°C. Subsequent doping with Co<sup>3+</sup> ions further improved densification, with the Li<sub>1.35</sub>Al<sub>0.29</sub>Co<sub>0.01</sub>Ti<sub>1.7</sub>P<sub>2.95</sub>Si<sub>0.05</sub>O<sub>12</sub> electrolyte reaching a peak relative density of 97.5% at 850&#xa0;°C. However, higher levels of Si<sup>4+</sup> or Co<sup>3+</sup> ions significantly degraded densification. X-ray diffraction results of the Li<sub>1.3+<i>x</i></sub>Al<sub>0.3</sub>Ti<sub>1.7</sub>P<sub>3−x</sub>Si<sub>x</sub>O<sub>12</sub> and Li<sub>1.35</sub>Al<sub>0.3−<i>y</i></sub>Co<sub><i>y</i></sub>Ti<sub>1.7</sub>P<sub>2.95</sub>Si<sub>0.05</sub>O<sub>12</sub> electrolytes identified a LiTi<sub>2</sub>(PO<sub>4</sub>)<sub>3</sub> phase with rhombohedral NASICON-type structure belonging to the <i>R</i><InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\:\overline{3}\)</EquationSource> </InlineEquation><i>c</i> space group, along with a small quantity of the LiTiOPO<sub>4</sub> phase. Substitution of Si<sup>4+</sup> ions into the Li<sub>1.3</sub>Al<sub>0.3</sub>Ti<sub>1.7</sub>(PO<sub>4</sub>)<sub>3</sub> lattice increased Li<sup>+</sup> ion transport channels due to the expansion of the cell volume. Raman spectroscopy and scanning electron microscopy revealed that the addition of both dopants improved the microstructure by enhancing the lattice structural order and leading to a higher degree of uniformity and smaller grains and higher crystallinity. X-ray photoelectron spectroscopy demonstrated that the incorporation of Si<sup>4+</sup> and Co<sup>3+</sup> ions into LATP lattice inhibited the reduction of Ti<sup>4+</sup> ions to Ti<sup>3+</sup> ions. The ionic conductivities of Li<sub>1.3+<i>x</i></sub>Al<sub>0.3</sub>Ti<sub>1.7</sub>P<sub>3−<i>x</i></sub>Si<sub><i>x</i></sub>O<sub>12</sub> electrolytes increased with higher Si<sup>4+</sup>-ion concentrations, reaching of 5.1 × 10<sup>− 4</sup> S/cm at 25&#xa0;°C. In the case of co-doping of Si<sup>4+</sup> and Co<sup>3+</sup> ions, Li<sub>1.35</sub>Al<sub>0.29</sub>Co<sub>0.01</sub>Ti<sub>1.7</sub>P<sub>2.95</sub>Si<sub>0.05</sub>O<sub>12</sub> composition exhibited the highest ionic conductivity of 1.0 × 10<sup>− 3</sup> S/cm at 25&#xa0;°C. The enhanced electrical conductivities were closely associated with high relative densities, excellent grain size uniformity, improved grain connectivity, and suppression of lower Ti<sup>4+</sup> ion reduction.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Effects of Si4+ and Co3+ co-doping on the structural and electrical conductivity of Li1.3Al0.3Ti1.7(PO4)3 ceramic electrolytes

  • 期刊论文

  • 发表日期：

    2025年6月10日

查看全文
  • Sea-Fue Wang,
  • Derrick Shieh,
  • Yen Ju Chen,
  • Yi-Le Liao,
  • Yung-Fu Hsu

摘要

In this study, we investigated the co-doping of Si4+ and Co3+ ions at the P5+ and Al3+ sites of the Li1.3Al0.3Ti1.7(PO4)3 electrolyte to enhance Li-ion conductivities. Si4+ doping increased the maximum relative density of the sintered Li1.3Al0.3Ti1.7(PO4)3 electrolyte, although it slightly raised the densification temperature. The Li1.35Al0.3Ti1.7P2.95Si0.05O12 electrolyte achieved 96.1% theoretical density at 925 °C. Subsequent doping with Co3+ ions further improved densification, with the Li1.35Al0.29Co0.01Ti1.7P2.95Si0.05O12 electrolyte reaching a peak relative density of 97.5% at 850 °C. However, higher levels of Si4+ or Co3+ ions significantly degraded densification. X-ray diffraction results of the Li1.3+xAl0.3Ti1.7P3−xSixO12 and Li1.35Al0.3−yCoyTi1.7P2.95Si0.05O12 electrolytes identified a LiTi2(PO4)3 phase with rhombohedral NASICON-type structure belonging to the R \(\:\overline{3}\) c space group, along with a small quantity of the LiTiOPO4 phase. Substitution of Si4+ ions into the Li1.3Al0.3Ti1.7(PO4)3 lattice increased Li+ ion transport channels due to the expansion of the cell volume. Raman spectroscopy and scanning electron microscopy revealed that the addition of both dopants improved the microstructure by enhancing the lattice structural order and leading to a higher degree of uniformity and smaller grains and higher crystallinity. X-ray photoelectron spectroscopy demonstrated that the incorporation of Si4+ and Co3+ ions into LATP lattice inhibited the reduction of Ti4+ ions to Ti3+ ions. The ionic conductivities of Li1.3+xAl0.3Ti1.7P3−xSixO12 electrolytes increased with higher Si4+-ion concentrations, reaching of 5.1 × 10− 4 S/cm at 25 °C. In the case of co-doping of Si4+ and Co3+ ions, Li1.35Al0.29Co0.01Ti1.7P2.95Si0.05O12 composition exhibited the highest ionic conductivity of 1.0 × 10− 3 S/cm at 25 °C. The enhanced electrical conductivities were closely associated with high relative densities, excellent grain size uniformity, improved grain connectivity, and suppression of lower Ti4+ ion reduction.