球磨法原位合成LiFePO4/CNTs复合材料及电化学性能

摘要

采用简单、有效和可规模化的球磨工艺,原位合成了碳纳米管( CNTs)均匀分布且连接磷酸铁锂( LiFe-PO4)颗粒的LiFePO4/CNTs复合材料。该复合材料颗粒均匀,分散性好,粒径大约在200 nm~1μm之间,其分散和连接状态可由碳纳米管和粘结剂调控。当CNTs含量为4 wt%、PVDF含量为5 wt%时复合材料显示出最好的电化学性能。0．25C 条件下首次放电容量达137 mAh·g-1,50次循环后,容量仍保持在95%以上,,显示出良好的循环稳定性和可逆性。与没有添加CNTs的样品相比,CNTs网络结构极大地提高了活性物质的电导率,从而明显改善电化学性能。%LiFePO4(LFP)microparticles connected homogeneously with three-dimensional(3D)carbon nanotube(CNT)conductive networks were successfully prepared via a simple,effective and high productivity by ball milling method. Scanning electron microsco-py( SEM) demonstrated that the LFP particles with the diameter ranging from several nanometers to one micron were connected by e-lectric bridge and the LFP particles could be well modulated by varying the amount of the CNTs and binder. The LFP/CNTs com-posite prepared using 4 wt%CNTs and 5 wt%PVDF exhibited the best electrochemical property with capacity of 137 mAh·g-1 and high capacity retention of 95%at 0. 25C after 50 cycles. Essentially,in comparison with those samples without CNT networks,this CNT network structure can greatly enhance the electrical conductivity,thus markedly improving the electrochemical performance.