A novel sol–gel synthesis route to NaVPO4F as cathode material for hybrid lithium ion batteries
A novel sol–gel synthesis route to NaVPO4F as cathode material for hybrid lithium ion batteries
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DOI：
10.1016/j.jpowsour.2010.04.003
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发表时间：
2010-10
影响因子：
9.2
通讯作者：
Jianqing Zhao;Jianping He;Xiaochu Ding;Jianhua Zhou;Yiou Ma;Shichao Wu;Ruiming Huang
中科院分区：
文献类型：
--
作者：
Jianqing Zhao;Jianping He;Xiaochu Ding;Jianhua Zhou;Yiou Ma;Shichao Wu;Ruiming Huang
采用改进的溶胶-凝胶法和热处理法制备了混合锂离子电池正极材料氟磷酸钒钠（NaVPO4F）。以钒（Ш）凝胶前驱体作为反应中间相，在常温条件下可方便地在乙醇中制备，大大简化了常规高温制备VPO4的过程。x射线衍射（XRD）结果表明，NaVPO4F由单斜晶向四方对称晶转变。同时，扫描电镜（SEM）图像显示样品的形貌有明显的空间重排。基于四边形NaVPO4F的混合锂离子电池在3.0 ~ 4.2 v的限定电压范围内，与锂相比，在3.6V时表现出均匀的放电平台，在C/4倍率下循环100次后，放电容量保持率高达98.7%。当电压漂移到3.0-4.5V时，初始充电和放电的可逆存储容量分别为117.3和106.8mAhg−1。此外，在2C速率下，制备的NaVPO4F在循环100次后的容量保留率为83%。电化学性能揭示了该氟磷酸盐材料的可逆混合碱离子（Li+, Na+）插入反应。
Sodium vanadium fluorophosphate, NaVPO4F, a cathode material for hybrid lithium ion batteries has been synthesized via a modified sol–gel method followed by heat treatment. The vanadium (Ш) gel precursor as the reaction intermediate phase can be facilely prepared in ethanol under ambient conditions, and this synthesis considerably simplifies the conventional high-temperature fabrication of VPO4. X-ray diffraction (XRD) results indicate a phase transition of NaVPO4F from the monoclinic crystal to the tetragonal symmetry structure. Meanwhile, the scanning electron microscope (SEM) images show the obvious spatial rearrangements on the morphology of samples. The hybrid lithium ion batteries based on the tetragonal NaVPO4F exhibit an even discharge plateau at 3.6V vs. Li in the limited voltage range of 3.0–4.2V, and the discharge capacity retention is up to 98.7% after 100 cycles at C/4 rate. With voltage excursion to 3.0–4.5V, the initial charge and discharge deliver the reversible storage capacity of 117.3 and 106.8mAhg−1, respectively. Furthermore, the prepared NaVPO4F has a capacity retention of 83% after 100th cycle at 2C rate. The electrochemical properties reveal the reversible mixed alkali ion (Li+, Na+) insertion reactions for this fluorophosphate material.