
Stabilizing fluorine to achieve high-voltage and ultra-stable Na
2021年4月1日 · The strategy of stabilizing fluorine can regulate the local electronic structure of vanadium and eliminate the low-voltage plateaus, thus achieving high-performance NVPF cathode. To understand how this works, the original cause of the “unknown” low-voltage plateaus is explored by MAS NMR, XPS and XRD.
Mastering the synergy between Na - ScienceDirect
2023年3月1日 · Using combined TEM, NMR, and IR analyses, together with electrochemical analyses of the different electrolyte/solvent leached samples, we observe a strong influence of the electrolyte formulation on V-dissolution that triggers structural changes in the NVPF material.
Higher energy and safer sodium ion batteries via an ... - Nature
2019年2月4日 · Here the authors realize a disordered tetragonal NVPF phase, which can reversibly uptake 3 Na-ions and enables improved energy density for the NVPF/C full cell.
钠离子电池正极材料氟磷酸钒钠研究进展 - cip
2022年11月4日 · 氟磷酸钒钠 [Na3V2(PO4)2F3,NVPF]正极材料具有稳定的三维框架结构、高的理论比容量 (128 mA·h/g)和高的工作电压 (约3.8 V)等优点,已成为近年来钠离子电池正极材料研究的热点。 然而,NVPF较低的电子电导率和较慢的离子扩散速率导致其实际比容量偏低且倍率性能不理想,阻碍了其进一步发展。 为此,研究者们通过优化NVPF的合成工艺,并采用包覆、离子掺杂和结构设计等方法对其进行改性,使其电化学性能得到了显著提升,极大增强了NVPF在钠 …
哈工大王振波教授课题组 Nano Energy:稳定氟以实现高压和超稳 …
2020年12月16日 · 在各类正极材料中,Na 3 V 2 (PO 4) 2 F 3 (NVPF)的理论工作电压约为3.85 V,理论比容量为128.3 mAh g -1,是一种极具前景的钠离子电池正极。 到目前为止,研究人员一直通过碳包覆、材料纳米化、离子掺杂等方式掺杂来改善NVPF的性能。 但是,大多数报导都忽略了一个重要现象,即NVPF正极的放电曲线中存在三个电压平台(相对于Na + /Na,约为4.1 V,3.6 V和3.3 V),但是理论上只有两个平台(相对于Na + /Na约为4.1 V和3.6 V)。 “未知”的3.3V …
Electrolytes and Interphases in Sodium‐Based Rechargeable …
Temperature-dependent PFG-NMR diffusion measurements showed that both FSI and TFSI have a comparable behavior although the smaller FSI anion is more diffusive. Lately, the group reported an unexpected elevated solubility of NaFSI salt in the Pyr 13 FSI IL, up to 3.2 mol kg −1 (50 mol %) at RT.
Recent progress and strategic perspectives of high-voltage …
2023年11月1日 · The NASICON structure of Na 3 V 2 (PO 4) 2 F 3 (NVPF) separates the valence electrons between the polyanion group and V and regulates the redox coupling energy. As a result, NVPF exhibits a high operating voltage in sodium-ion batteries. However, NVPF cathode material has poor specific capacity and low-rate performance.
A new high-voltage calcium intercalation host for ultra-stable ... - Nature
2021年6月7日 · Structural analyses coupled with in situ XRD, solid state NMR, XANES, and STEM revealed the reversible insertion and removal of Ca 2+ ions in the NVPF framework with an ultra-small volume...
a-b) 31 P MAS NMR spectra and 23 Na MAS NMR spectra of NVPF…
Moreover, the 31 P NMR spectrum of Na2-charged recovered after the DSC experiment (Figure 5b) displays a main signal at 6000 ppm (compared to 3780 ppm before DSC (Figure3a)) which validates the...
东北师大吴兴隆Adv. Mater.:先进的高电压、高能量密度高熵氟磷 …
近日, 东北师范大学吴兴隆教授课题 组针对氟磷酸钒钠正极进行研究,引入 高熵 设计理念,开发了高熵氟磷酸盐(HE-NVPF)正极,实现了 氟磷酸盐 正极材料工作电压和能量密度的提升。 该高熵氟磷酸盐不仅抑制了NVPF原有低压区的相转变,而且提升了NVPF的电子电导率和降低了钠离子迁移过程能垒,表现出优异的循环和倍率性能。