论文部分内容阅读
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%。
LiFe_xMn_ (1-x) PO_4 / C composites were prepared by introducing solid solution into the Li Mn PO4 lattice with phenolic resin as reductant and carbon source. The effects of iron content, calcination temperature and calcination time on the electrochemical properties of the materials were investigated. The results show that the prepared LiFe_xMn_ (1-x) PO_4 / C is an olivine phase with high purity and spherical morphology with a particle size of 300-500 nm and uniform distribution. The results of cyclic charge and discharge tests showed that the plateau capacities at Fe ~ (2 +) / Fe ~ (3+) and Mn ~ (3 +) / Mn ~ (2+) redox potentials were Rise and fall accordingly. The LiFe0.5Mn0.5PO4 / C sample prepared by calcination at 600 ℃ for 10 h had good electrochemical performance: the first discharge capacity at 0.1 C rate was 147.3 mAh / g; and after 100 cycles at 2 C rate, the discharge capacity increased from 115.2 m Ah / g was reduced to 112.7 m Ah / g, and the capacity retention was 97.8%. After 200 cycles of 10 C rate, the capacity retention was still 89.6%.