Sapra Simranjot K, Chang Jeng-Kuei, Dhaka Rajendra S
Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
International College of Semiconductor Technology, National Yang Ming Chiao Tung University, 1001 University Road, Hsinchu 30010, Taiwan.
ACS Appl Mater Interfaces. 2024 Aug 21;16(33):43535-43547. doi: 10.1021/acsami.4c07348. Epub 2024 Aug 6.
In recent years, the Na-ion SuperIonic CONductor (NASICON) based polyanionics are considered pertinent cathode materials in sodium-ion batteries due to their 3D open framework, which can accommodate a wide range of Na content and can offer high ionic conductivity with great structural stability. However, owing to the inferior electronic conductivity, these materials suffer from unappealing rate capability and cyclic stability for practical applications. Therefore, in this work we investigate the effect of Co substitution at the V site on the electrochemical performance and diffusion kinetics of NaVCo(PO)/C ( = 0-0.15) cathodes. All the samples are characterized through Rietveld refinement of the X-ray diffraction patterns, Raman spectroscopy, transmission electron microscopy, etc. We demonstrate improved electrochemical performance for the = 0.05 electrode with a reversible capacity of 105 mAh g at 0.1 C. Interestingly, the specific capacity of 80 mAh g is achieved at 10 C with retention of about 92% after 500 cycles and 79.5% after 1500 cycles and having nearly 100% Coulombic efficiency. The extracted diffusion coefficient values through the galvanostatic intermittent titration technique and cyclic voltammetry are found to be in the range of 10 to 10 cm s. The post-mortem studies show excellent structural and morphological stability after testing for 500 cycles at 10 C. Our study reveals the role of optimal dopant of Co ions at the V site in improving the cyclic stability at a high current rate.
近年来，基于钠离子超离子导体（NASICON）的聚阴离子材料因其三维开放框架而被认为是钠离子电池中相关的阴极材料，该框架可容纳广泛的钠含量，并能在具有高结构稳定性的情况下提供高离子电导率。然而，由于电子电导率较差，这些材料在实际应用中存在速率性能和循环稳定性不佳的问题。因此，在本工作中，我们研究了在V位点上Co取代对NaVCo(PO)/C（ = 0 - 0.15）阴极的电化学性能和扩散动力学的影响。所有样品均通过对X射线衍射图谱进行Rietveld精修、拉曼光谱、透射电子显微镜等进行表征。我们证明了 = 0.05电极具有改善的电化学性能，在0.1 C时可逆容量为105 mAh g。有趣的是，在10 C时比容量达到80 mAh g，在500次循环后保留约92%，在1500次循环后保留79.5%，并且库仑效率接近100%。通过恒电流间歇滴定技术和循环伏安法提取的扩散系数值在10至10 cm s范围内。死后研究表明，在10 C下测试500次循环后，结构和形态稳定性优异。我们的研究揭示了在V位点上Co离子的最佳掺杂剂在提高高电流速率下的循环稳定性方面的作用。
