摘要
通过固相反应法合成出Li3＋xFe2-xMn^Ⅱ（PO4）3（x=0～0．1）、Li3Fe1．95Mn0.05^Ⅲ（PO4）3和Li2．95Fe1．95Mn0.05^Ⅳ（PO4）3正极材料。采用行星式球磨方法，均匀混合正极材料和导电乙炔黑以提高活性材料的电子导电率和降低颗粒尺寸。Mn掺杂的Li3Fe2（PO4）3样品的恒电流充放电测试和伏安循环测试（2～4V）发现，所有样品中Fe^3＋／Fe^2＋氧化还原电对均有两个稳定的充放电平台（2．8、2．7V）、Li3＋xFe2-xMnx^Ⅱ（PO4）3和Li3Fe1．95Mn0.05^Ⅲ（PO4）3中Mn^3＋／Mn^2＋电对的充放平台位于3．5V左右。不同价态Mn的掺杂均可明显提高正极材料的电化学性能，其中Mn^Ⅱ掺杂样品的电化学性能最好，其中Li3.05Fe1．95MnⅡ0．05（PO4）3／C的C／20和C／2恒流放电比容量分别可达110和66mAh／g。
The monoelinie Li3＋xFe2-xMn^Ⅱ（PO4）3（x=0～0.1）, Li3 Fe1. 95 Mn0.05^Ⅲ（PO4）3 and Li2.95 Fe1.95 Mn0.05^Ⅳ（PO4）3 cathodes were synthesized by solid state reaction. The synthesized powders were ball-milled with aeethylene carbon to reduce the particle sizes and improve the electronic conductivity of the active materials. The galvanostatic charge/discharge test and the cyclic vohammetry （C-V） revealed that all of them had two plateau potentials of Fe^3＋/Fe^2＋ couple vs. Li/Li^＋ at 2.8 and 2.7V upon discharge. The plateau potential of Mn^3＋/Mn^2＋ at 3.5V was observed in Li3＋xFe2-xMnx^Ⅱ （PO4）3 and Li3Fe1.95 Mn0.05^Ⅲ （PO4）3 cathodes. Furthermore, the Mn doping was demonstrated to be able to improve the electrochemical performances of the cathodes. In all the samples, the Li3.05Fe1.95Mn^Ⅱ 0.05（PO4）3/C cathode showed the best electrochemical performances and possessed the discharge capacities of 110mAh/g at C/20 and 66mAh/g at C/2.
出处
《功能材料》
EI
CAS
CSCD
北大核心
2009年第4期604-607,610,共5页
Journal of Functional Materials
基金
国家重点基础研究发展计划(973计划)资助项目(2007CB936704)
国家自然科学基金资助项目(50772123)
