聚苯胺在LiCoO_2和LiMn_2O_4正极中的双重功能

Dual function of polyaniline in positive electrodes of LiCoO_2 and LiMn_2O_4

用化学聚合法合成聚苯胺(PAn),并考察其在LiCoO2和LiMn2O4正极中的双重功能。结果表明:在优化条件下PAn的产率y=94.06%、导电率σ=18.39 S/cm,大于乙炔黑(AB)的导电率σ=7.77 S/cm;以制备的PAn为锂离子电池正极活性材料,在不添加其他导电剂对其进行恒电流充、放电试验(电流密度J=15 mA/g)时,第三循环的比放电容量D3=60.8 mA.h/g、充、放电效率η3=94.56%;PAn在正极中兼有活性材料的功能;以LiCoO2和尖晶石LiMn2O4为正极活性材料,以PAn替代AB作为导电剂进行恒电流充、放电试验,在电流密度分别为15、30、45和60 mA/g时,比充、放电容量都增大,表明正极的极化程度减小;正极在经过较大电流密度(60 mA/g)充、放电后,再以小电流密度(15 mA/g)进行充、放电时,比充、放电容量几乎没有变化,表明经较大电流密度(60 mA/g)充、放电后,LiCoO2和尖晶石LiMn2O4的贮锂结构没有改变。

Polyaniline（PAn） was produced by chemical polymerization.The dual function of PAn in positive electrodes of LiCoO2 and LiMn2O4 was investigated.The results show that under the optimized conditions,the yield of PAn is y=94.06% and its electronic conductivity is σ=18.39 S/cm,which is greater than that of acetylene black（AB）（σ=7.77 S/cm）.The galvanostatic experiment（current density J=15 mA/g） with the above PAn as the positive electrode active material was carried out,and no other electronic conductive reagent was used.In the third cycle,the specific discharge capacity（D3） is 60.8 mA·h/g,the charge and discharge efficiency η3 is 94.56%.PAn in the positive electrodes has the function of active materials.The galvanostatic experiments were carried out with the LiCoO2 and spinel LiMn2O4 as the positive electrode active materials and the PAn was used as the electronic conductive reagent to take place of AB.When the current densities are 15,30,45 and 60 mA/g,all the specific charge and discharge capacities increase.After charging and discharging with large current density（60 mA/g）,the positive electrode charged and discharged with the original small current density（15 mA/g）.The specific charge and discharge capacities are almost unchanged.It shows that the storing lithium ions structures of LiCoO2 and spinel LiMn2O4 do not change.