Preparation and characterization of Co2+ doped graphene/LiFePO4 composite cathode materials for lithium battery
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摘要: 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200 nm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。2.0~4.0 V充放电下0.1 C时的首次放电比容量为159 mA·h·g-1, 在10.0 C下首次放电比容量也有74 mA·h·g-1;0.5 C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。Abstract: In order to obtain lithium ion battery cathode materials with high specific capacity, fast charging and discharging rate and excellent cycle performance, Co2+ doped graphene/LiFePO4 composite cathode materials for lithium battery (graphene/LiCo0.03Fe0.97PO4) were synthesized by using a sol-gel in-situ carbothermal reduction treatment. The structure and morphology characterization results show that graphene/LiCo0.03Fe0.97PO4 composites form 3D conducting network structure. The particles grow homogeneously in graphene sheets with the diameters of about 200 nm. The electrochemical test results show that graphene/LiCo0.03Fe0.97PO4 composites exhibit high reversible specific capacity and superior cycle rate performance with the first discharge specific capacity of 159 mA·h·g-1 at 0.1 C (2.0-4.0 V charge-discharge) and 74 mA·h·g-1 at 10.0 C of the first discharge. The specific capacity retention is 99.7% after 100 cycles at 0.5 C. The enhanced electrochemical property of graphene/LiCo0.03Fe0.97PO4 composites is attributed to the synergistic effect of Co2+ doping and graphene-modification.
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Key words:
- composites /
- graphene /
- in-situ carbothermal reduction /
- electrochemical properties /
- LiFePO4
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