Fe掺杂LiMnPO_4/C的制备和电化学性能

Synthesis and Electrochemical Performance of LiMnPO_4/C with Fe Ion Dopant

以酚醛树脂作为还原剂和碳源,采用固相法在Li Mn PO4晶格中引入铁离子制备了Li Fe_xMn_(1-x)PO_4/C复合材料。考察了掺铁量、煅烧温度和煅烧时间对材料电化学性能的影响。结果表明,制备的Li Fe_xMn_(1-x)PO_4/C为纯度较高的橄榄石型相,具有类球形形貌,颗粒尺寸300~500 nm,且分布均匀。循环充放电测试结果表明,随着掺铁量的增加,Fe^(2+)/Fe^(3+)和Mn^(3+)/Mn^(2+)氧化还原电位处的平台容量分别相应地升高和下降。其中600℃煅烧10 h制得的Li Fe0.5Mn0.5PO4/C样品具有较好的电化学性能:0.1 C倍率首次放电容量为147.3 m Ah/g;2 C倍率循环100次后,放电容量从115.2 m Ah/g降至112.7 m Ah/g,容量保持率为97.8%;10 C倍率循环200次后,容量保持率仍有89.6%。

A series of Li FexMn1-xPO4/C composite materials was synthesized using a solid-state reaction method, and Fe ion was doped into crystalline of Li Mn PO4 for the improvement of electrochemical performance. The phenolic resin was added as the reducing agent and carbon sources. The effect of Fe-to-Mn ratio, calcination temperature and calcination time on the electrochemical performance was investigated. Results reveal that Li FexMn1-xPO4/C has an order olivine structure and high purity. Samples have the similarly spherical morphology with particle size of 300500 nm and uniform distribution. The outcomes of charge-discharge measurement show that the capacity at the voltage plateaus due to the Fe2＋/Fe3＋ and Mn3＋/Mn2＋ redox groups increases and decreases, respectively, with Fe content increasing, and the Li Fe0.5Mn0.5PO4/C sample calcined at 600 oC for 10 h exhibits higher capacity and better rate-cycling performance, including the first discharge capacity 147.3 m Ah/g at 0.1 C, the discharge capacity of 115.2 m Ah/g decreasing to 112.7 m Ah/g at 2C as well as the capacity retention rate 97.8% after 100 cycles and the capacity retention rate 89.6% after 200 cycles at 10 C.