Unraveling Processing-Structure-Electrical Conductivity Relationships of NaCrO2 Cathodes for Na-ion Batteries
Unraveling Processing-Structure-Electrical Conductivity Relationships of NaCrO2 Cathodes for Na-ion Batteries
复制标题
揭示钠离子电池 NaCrO2 阴极的加工-结构-电导率关系
DOI：
10.1149/2.0081915jes
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发表时间：
2019
影响因子：
3.9
通讯作者：
Shaw, L.
中科院分区：
文献类型：
--
作者：
Luo, M.;Ortiz, A. L.;Shaw, L.
研究了以Na 2CO 3和Cr2 O3为原料，经机械活化和未经机械活化的NaCrO 2粉体在高温反应前的室温电导率。研究了900 ℃保温时间对电导率的影响。结果表明，合成条件对粉体中的杂质和晶体的结构缺陷有很大的影响。杂质尤其是晶体缺陷对NaCrO 2粉体的电导率有很大的影响。特别地，发现NaCrO 2的电导率主要由Cr+ 3离子在O3-NaCrO 2层状结构的Na位中的错位程度控制。当Cr+ 3离子在Na位上的错置率只有0.34%时，体离子电导率被确定为9.8× 10− 7 S/cm，但当错置率增加到9.97%时，体离子电导率下降到1.7× 10− 7 S/cm。这种错位越多电导率越低的强烈相关性归因于O3-NaCrO 2层状结构中错位的Cr+ 3离子阻碍了Na离子在Na平面上的输运。
The electrical conductivities of NaCrO 2 powders synthesized from Na 2 CO 3 and Cr 2 O 3 reactants with and without mechanical activation at room temperature before the high temperature reaction are investigated in detail. The effect of holding time at the 900 C reaction on the electrical conductivity is studied as well. It is found that the impurities in the powders and structural defects of the resulting NaCrO 2 crystals strongly depend on the synthesis conditions. The impurities and specially the crystal defects, in turn, influence the electrical conductivity of NaCrO 2 powders substantially. In particular, the electrical conductivity of NaCrO 2 is found to be mainly controlled by the degree of misplacement of Cr+ 3 ions in the Na sites of the O3-NaCrO 2 layered structure. The bulk ionic conductivity is determined to be 9.8× 10− 7 S/cm when there is only 0.34% misplacement of Cr+ 3 ions in the Na sites, but drops to 1.7× 10− 7 S/cm when the misplacement increases to 9.97%. Such a strong correlation of more misplacement with lower electrical conductivity is attributed to blocking of Na ion transport on the Na plane by the misplaced Cr+ 3 ions in the O3-NaCrO 2 layered structure.