电化学
阴极
价(化学)
分析化学(期刊)
循环伏安法
介电谱
化学
快离子导体
无机化学
离子
兴奋剂
X射线光电子能谱
材料科学
电极
物理化学
核磁共振
电解质
光电子学
色谱法
物理
有机化学
作者
Dipika Meghnani,Shri Singh,Nitin Srivastava,Rupesh K. Tiwari,Raghvendra Mishra,Anupam Patel,Anurag Tiwari,Rajendra Kumar Singh
标识
DOI:10.1002/cphc.202200459
摘要
The sodium superionic conductor (NASICON)-Na3 V2 (PO4 )3 (NVP) is an attractive cathode for sodium-ion batteries, which is still confronted with limited rate performance due to its low electronic conductivity. In this paper, a chemical strategy is adopted to partially replace V3+ of the NVP framework by low-valence Mn2+ and high-valence Mo6+ substitution. The crystal structure, sodium-ion diffusion coefficient and electrochemical performance of Mn-Mo-doped [Na3.94 V0.98 Mo0.02 Mn(PO4 )3 @C] cathode were investigated. X-ray diffraction confirmed the NASICON-type structure and XPS analysis confirmed the oxidation state of Mn and Mo in doped NVP cathode. The Na ion diffusion processes were inferred from Cyclic Voltammetry (CV), Galvanostatic intermittent titration technique (GITT) and Electrochemical Impedance Spectroscopy (EIS) measurement, which clearly show rapid Na-ion diffusion in NASICON-type cathode materials. The Mn-Mo-substituted NVP shows smoother charge-discharge profiles, improved rate performance (64.80 mAh/g at 1 C rate), better energy density (308.61 mWh/g) and superior Na-ion kinetics than that of unsubstituted NVP@C cathode. Their enhanced performance is attributed to large interstitial volume mainly created by high valence Mo6+ and enhanced capacity is attributed to the low valence Mn2+ doping. These results demonstrate that Mn-Mo-doped NVP cathode is strongly promising cathode material for sodium-ion batteries.
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