Ghosh Subham, Barman Nabadyuti, Senguttuvan Premkumar
New Chemistry Unit, International Centre for Materials Science and School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, Karnataka, 560064, India.
Small. 2020 Nov;16(45):e2003973. doi: 10.1002/smll.202003973. Epub 2020 Oct 20.
Sodium superionic conductor (NASICON)-Na VMn(PO ) (NVMP) cathode is attractive for sodium-ion battery application due to its reduced cost and toxicity, and high energy density (≈425 Wh kg ). However, it exhibits significant polarization, limited rate and cycling performances due to its lower electronic conductivity and formation of Jahn-Teller active Mn during cycling. In this report, a chemical approach is presented to partially replace Mn of the NVMP framework by Mg and Al substitutions. The Mg- and Al-substituted NVMP cathodes present smoother voltage profiles, facile sodium (de)intercalation, enhanced rate performances (80 mA h g at 5C rate) and capacity retention (≈96% after 100 cycles) in comparison with the unsubstituted sample. Their enhanced performances are attributed to suppressed Jahn-Teller effect, increased covalent character and sodium ion vacancies of the NASICON framework. These results highlight the significance of fine tuning the chemical compositions to attain high performance NASICON cathodes.
钠超离子导体（NASICON）-NaVMn(PO₄)₃（NVMP）正极因其成本降低、毒性低以及高能量密度（约425瓦时/千克）而在钠离子电池应用中具有吸引力。然而，由于其较低的电子电导率以及在循环过程中形成Jahn-Teller活性锰，它表现出显著的极化、有限的倍率和循环性能。在本报告中，提出了一种化学方法，通过用镁和铝取代来部分替代NVMP骨架中的锰。与未取代的样品相比，镁和铝取代的NVMP正极呈现出更平滑的电压曲线、容易的钠（脱）嵌入、增强的倍率性能（5C倍率下为80毫安时/克）和容量保持率（100次循环后约为96%）。它们增强的性能归因于抑制了Jahn-Teller效应、增加了NASICON骨架的共价特性和钠离子空位。这些结果突出了微调化学成分以获得高性能NASICON正极的重要性。
