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使用溶胶凝胶原位碳热还原制备了Co2+掺杂石墨烯/LiFePO4锂离子电池复合正极材料(石墨烯/LiCo0.03Fe0.97PO4),以期获得比容量高、充放电速率快和循环性能优良的锂离子电池正极材料。结构和形貌表征结果显示:石墨烯/LiCo0.03Fe0.97PO4复合材料具有三维导电网络结构,颗粒在石墨烯片层间生长均匀,粒径在200nm左右。电化学测试结果显示:石墨烯/LiCo0.03Fe0.97PO4复合材料具有高的可逆比容量和优异的循环倍率性能。2.0~4.0V充放电下0.1C时的首次放电比容量为159mA·h·g-1,在10.0C下首次放电比容量也有74mA·h·g-1;0.5C下循环100次,比容量保持率为99.7%。石墨烯/LiCo0.03Fe0.97PO4复合材料电化学性能提高的原因主要为Co2+掺杂和石墨烯包覆的协同作用。
Co2 + doped graphene / LiFePO4 lithium ion battery composite cathode material (graphene / LiCo0.03Fe0.97PO4) was prepared by sol-gel in-situ carbothermal reduction in order to obtain high specific capacity, fast charge and discharge rate and excellent cycle performance Lithium-ion battery cathode material. The results show that the graphene / LiCo0.03Fe0.97PO4 composite has a three-dimensional conductive network structure and the particles grow uniformly in the graphene sheets with particle size about 200nm. The results of electrochemical tests show that the graphene / LiCo0.03Fe0.97PO4 composites have high reversible specific capacity and excellent cycling rate performance. The initial discharge specific capacity at 0.1 C under charge and discharge of 2.0-4.0 V was 159 mA · h · g-1, and the initial discharge specific capacity was also 74 mA · h · g-1 at 10.0 C. The cycle capacity was 100 cycles at 0.5 C, Retention rate of 99.7%. The main reason for the improvement of electrochemical performance of graphene / LiCo0.03Fe0.97PO4 composites is the synergistic effect of Co2 + doping and graphene coating.