Abstract:

Button batteries (OB-1, OB-2) and full batteries (FB-1, FB-2, mass production) of LiFePO₄ were prepared by using ordinary aluminum foil and carbon coated aluminum as current collector, respectively. The properties of the foils and batteries were characterized with scanning electron microscope, X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy, and the electrochemical performance was investigated with electrochemical impedance spectroscopy and galvanostatic charge-discharge tests. The performance at different conditions was used to investigate the influence of carbon coated aluminum. The results show that the property of foil affected the Li⁺ transfer rate and the electrochemical performance. However, the influence at low temperature is greater than that at room temperature. The use of carbon coated aluminum foil is beneficial to decreasing the internal resistance of batteries, and to improving the charge-discharge performance at low temperature. The transfer rate of Li⁺ and the discharging capacity of OB-2 at -20℃ was 1.1×10^-12m²/s and 92.7mA·h/g, respectively. In addition, the capacity of FB-2 at -20℃ was still 72.2% after 100 cycles.

Key words: carbon coated aluminum foil, LiFePO₄, power battery, diffusion, electrochemistry

摘要：

分别以普通铝箔和涂碳铝箔为正极集流体制备磷酸铁锂（LiFePO₄）扣式电池（OB-1、OB-2）和全电池（FB-1、FB-2，批量生产）。采用扫描电子显微镜、X射线光电子能谱和电化学工作站对正极箔材和所组装的电池进行表征，并对其电化学性能进行研究，根据所组装电池在不同条件下的充放电性能判断涂碳铝箔对磷酸铁锂动力电池充放电性能的影响。结果表明，涂碳铝箔有利于提高Li⁺扩散速率和充放电性能。然而，涂碳铝箔对电池在低温环境中的充放电性能影响更大。以涂碳铝箔为集流体可以降低电池内阻，提高电池低温充放电性能。温度为-20℃时，OB-2中Li⁺扩散速率可达1.1×10^-12m²/s，放电容量为92.7mA·h/g，全电池FB-2循环充放电100次，容量保持率可达72.2%。

关键词: 涂碳铝箔, 磷酸铁锂, 动力电池, 扩散, 电化学