A comparative study on the low-temperature performance of LiFePO4/C and Li3V2(PO4)(3)/C cathodes for lithium-ion batteries
A comparative study on the low-temperature performance of LiFePO4/C and Li3V2(PO4)(3)/C cathodes for lithium-ion batteries
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DOI：
10.1016/j.jpowsour.2010.10.063
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发表时间：
2011-02
影响因子：
9.2
通讯作者：
X. Rui;Yao-Jun Jin;Xuyong Feng;Liang Zhang;C. H. Chen
中科院分区：
文献类型：
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作者：
X. Rui;Yao-Jun Jin;Xuyong Feng;Liang Zhang;C. H. Chen
采用锂离子半电池，在1.0M LiPF6/EC+DMC （1:1w/w）电解液中，研究了LiFePO4/C （LFP/C）和Li3V2(PO4)3/C （LVP/C）样品在23、0、−10和−20℃不同低温下的电化学性能。在2.5 ~ 4.3 v电压范围内，在0.3C速率下，LFP/C电极在−20℃时的可逆放电容量为45.4mAhg−1，为23℃时的31.5%。在0.3C速率下3.0-4.3V电压范围内，LVP/C电极在−20°C时具有108.1mAhg−1at的高稳定可逆放电容量，是23°C时容量的86.7%。电化学阻抗谱（EIS）和循环伏安法（CV）测试表明，LFP/C在不同低温下的电阻和电池极化均大于LVP/C。此外，利用CV法，在不同低温条件下，LFP和LVP中锂离子的表观化学扩散系数（[公式：见文]）分别在10−11和10−10cm2s−1量级，且LFP随温度的下降速率[公式：见文]远大于LVP，说明LFP电极动力学相对缓慢。LFP和LVP的活化能分别为47.48和6.57kJmol−1，这进一步表明LVP比LFP更容易提取/插层Li+。LVP/C在- 20°C时的高可逆容量使其成为低温锂离子电池极具吸引力的阴极。
The electrochemical properties of the LiFePO4/C (LFP/C) and Li3V2(PO4)3/C (LVP/C) samples are investigated using Li-ion half cells at various low temperatures of 23, 0, −10 and −20°C in the electrolyte 1.0M LiPF6/EC+DMC (1:1w/w). In the voltage range of 2.5–4.3V at 0.3C rate, the LFP/C electrode shows a stable reversible discharge capacity of 45.4mAhg−1at −20°C, which is 31.5% of the capacity obtained at 23°C. In the voltage range of 3.0–4.3V at 0.3C rate, the LVP/C electrode delivers a high stable reversible discharge capacity of 108.1mAhg−1at −20°C, being 86.7% of the capacity at 23°C. The electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) measurements illustrate that the resistance and cell polarization of LFP/C at various low temperatures are larger than those of LVP/C. In addition, using CV method, the apparent chemical diffusion coefficient of lithium ions ( [Formula: see text] ) in LFP and LVP at various low temperatures are in the magnitude of 10−11and 10−10cm2s−1, respectively, and the [Formula: see text] decreasing rate of LFP as the temperature is much larger than LVP, meaning that the kinetics of the LFP electrode is relatively slow. The activation energies of LFP and LVP are calculated to be 47.48 and 6.57kJmol−1, respectively, which further indicates that the extraction/intercalation of Li+in LVP is much easier than in LFP. The high reversible capacity of LVP/C at −20°C makes it an attractive cathode for low-temperature lithium ion batteries.