摘要
以蔗糖为碳源,用高温固相法制备了Li0.96Mg0.02FePO4/C、LiFe0.98Mg0.02PO4/C和不确定掺杂位的样品LiFePO4/C+Mg2+的正极材料。用XRD、SEM、恒流充放电测试、循环伏安和交流阻抗谱方法,研究了样品的结构、形貌及电化学性能。研究发现,样品均为单一规则的橄榄石型的LiFePO4结构。在0.2 C(1 C=150 mAh/g)倍率下放电,Li0.96Mg0.02FePO4/C、LiFe0.98Mg0.02PO4/C最大放电比容量分别为138.2、142.6 mAh/g,LiFePO4/C+Mg2+的最大放电比容量最小,为102.1 mAh/g;经过20次充放电循环后,Li0.96Mg0.02FePO4/C的容量衰减3%,LiFe0.98Mg0.02PO4/C的容量几乎没衰减,LiFePO4/C+Mg2+的容量衰减最大。
Li0.96Mg0.02FePO4/C,LiFe0.98Mg0.02PO4/C and uncertain substitute LiFePO4/C＋Mg2＋ cathode materials were synthesized by high-temperature solid-state reaction with sucrose as carbon source.The structure,morphology and electrochemical performance of the samples were tested by XRD,SEM,galvanostatic charge-discharge test,cyclic voltammogram and AC impedance methods.The results show that all samples are pure phases with an ordered olivine structure.The biggest specific discharge capacity of Li0.96Mg0.02FePO4/C and LiFe0.98Mg0.02PO4/C are 138.2 mAh/g and 142.6 mAh/g at 0.2 C（1 C =150 mAh/g）,respectively.The biggest specific discharge capacity of Li0.96Mg0.02FePO4/C is 102.1 mAh/g,which is the smallest in three samples.Furthermore,the capacity fading of Li0.96Mg0.02FePO4/C is 3%,and there is almost no capacity fading of LiFe0.98Mg0.02PO4/C after 20 cycles.In comparison,the capacity loss of LiFePO4/C＋Mg2＋ is biggest after 20 cycles.
出处
《电源技术》
CAS
CSCD
北大核心
2011年第3期248-251,共4页
Chinese Journal of Power Sources
基金
青海省重点科技攻关项目(2006-G-168)
