Towards highly stable storage of sodium ions: a porous Na(3)V(2)(PO(4))(3)/C cathode material for sodium-ion batteries.
Towards highly stable storage of sodium ions: a porous Na(3)V(2)(PO(4))(3)/C cathode material for sodium-ion batteries.
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DOI：
10.1002/chem.201300005
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发表时间：
2013-10
期刊：
影响因子：
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通讯作者：
Wei Shen;Cong Wang;Haimei Liu;Wensheng Yang
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文献类型：
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作者：
Wei Shen;Cong Wang;Haimei Liu;Wensheng Yang
采用溶胶-凝胶法结合冷冻干燥工艺合成了均匀包覆约6 nm碳层的多孔Na3 V2 (PO4 )3正极材料。特殊的多孔形貌和结构显着增加了材料的比表面积，从而大大扩大了电极与电解质之间的接触面积，从而为钠离子提供了更多的活性位点。当用作钠离子电池正极材料时，这种多孔Na3 V2 (PO4 )3 /C表现出优异的倍率性能和循环稳定性；例如，它在相对于Na(+)/Na的2.7-4.0 V电位窗口内的3.4 V处表现出相当平坦的电位平台，并在0.05和0.5 C的倍率下分别提供高达118.9和98.0 mAh g(-1)的初始容量，并且在50次循环后，保持了92.7%和93.6%的良好容量保持率。而且，即使当放电电流密度增加到5 C（590 mA g(-1) ）时，仍能实现97.6 mA h g(-1)的初始容量，并且在100次循环后获得88.6%的励磁容量保持率。 Na3 V2 (PO4 )3 /C良好的循环性能、优异的倍率性能以及低成本表明该材料是一种有前途的大型钠离子充电电池正极材料。
A porous Na3 V2 (PO4 )3 cathode material coated uniformly with a layer of approximately 6 nm carbon has been synthesized by the sol-gel method combined with a freeze-drying process. The special porous morphology and structure significantly increases the specific surface area of the material, which greatly enlarges the contact area between the electrode and electrolyte, and consequently supplies more active sites for sodium ions. When employed as a cathode material of sodium-ion batteries, this porous Na3 V2 (PO4 )3 /C exhibits excellent rate performance and cycling stability; for instance, it shows quite a flat potential plateau at 3.4 V in the potential window of 2.7-4.0 V versus Na(+) /Na and delivers an initial capacity as high as 118.9 and 98.0 mA h g(-1) at current rates of 0.05 and 0.5 C, respectively, and after 50 cycles, a good capacity retention of 92.7 and 93.6 % are maintained. Moreover, even when the discharge current density is increased to 5 C (590 mA g(-1) ), an initial capacity of 97.6 mA h g(-1) can still be achieved, and an exciting capacity retention of 88.6 % is obtained after 100 cycles. The good cycle performance, excellent rate capability, and moreover, the low cost of Na3 V2 (PO4 )3 /C suggest that this material is a promising cathode for large-scale sodium-ion rechargeable batteries.