空心微球聚苯胺二次锂氧电池正极材料研究

HOLLOW MICROSPHERICAL POLYANILINE AS CATHODE MATERIALS IN RECHARGEABLE LITHIUM-OXYGEN BATTERY

以铁氰化钾为氧化剂,在水溶液中引发苯胺单体聚合生成具有较高电导率的空心微球结构的聚苯胺.电化学测试结果表明,这种廉价易得的高分子材料能够作为锂氧电池的正极材料独立高效地催化电池反应的发生.在首次充放电过程中,该正极材料的能量密度能够达到2631 mAh/g PANI,是常规非空心聚苯胺材料的2倍左右,而在最初的5次循环过程中发生了较明显的能量密度衰减之后,其在后续的25次充放电循环过程中保持了较为理想的循环稳定性,能量密度仅衰减了5%左右.该空心微球聚苯胺材料具有较高的能量密度和较好的循环稳定性.

A facile method to prepare the hollow microspherical polyaniline was developed utilizing potassium hexacyanoferrate(Ⅲ) as the oxidant for polymerization of aniline in aqueous condition without any acid or alkali or organic solvent,and the doped polyaniline with electrical conductivity of 10-3 S/cm could be directly obtained with hexacyanoferrate(Ⅱ) anion surrounding imine and amine atoms in polyaniline main-chain.And this value was almost seven orders of magnitude higher than the polyaniline hollow spheres synthesized in alkaline medium.This product was then characterized by Fourier transform infrared(FTIR) spectroscopy,X-ray photoelectron spectroscopy(XPS) and scanning electron microscopy(SEM).A systematic and careful electrochemical test was carried out to deeply investigate its potential application for lithium-oxygen battery.The experimental results show that,this low cost and easily produced material could catalyze the battery discharge reaction independently,and its first discharge capacity is almost twice as high as that for the cathode made by traditional bulk polyaniline material.After an initial degradation from 2631 to 1748 mAh/g PANI during the first 5 cycles at a current density of 0.05 mA/cm-1,its discharge capacity kept relatively stable in the next 25 cycles with only 5% loss,which may provide a new choice for fabrication of high-capacity rechargeable lithium-oxygen battery for practical application.