(苏州大学 沙钢钢铁学院，苏州 215021)
摘 要: 采用共沉淀法制备掺Al3+前驱体FePO4·2H2O，并以乙二酸为还原剂，与Li2CO3反应在常温下球磨合成LiFePO4前驱混合物，后经热处理得到橄榄石型LiFe1-3y/2AlyPO4。用XRD、SEM、HRTEM和恒流充放电等对样品进行表征。结果表明：适量Al3+掺杂不会破坏 LiFePO4的晶体结构，当掺杂量较低时(y=0.01)，Al3+优先占据Fe位；当掺杂量较高时(y≥0.02)，Al3+同时占据Li位和Fe位。电化学测试表明：LiFe0.985Al0.01PO4拥有最优的电化学性能，该样品在0.1C、1C和2C倍率下的首次放电比容量分别为162.4、152.2和142.0 mA？h/g，在1C倍率下循环100次后的放电比容量高达149.7 mA？h/g。
关键字: 正极材料；磷酸铁锂；Al3+掺杂；球磨；常温还原
（School of Iron and Steel, Soochow University, Suzhou 215021, China）
Abstract:Al3+-doped precursors (FePO4·2H2O) were prepared via a co-precipitation method. LiFePO4 precursor- mixtures were obtained by ball milling at room temperature using FePO4·2H2O, Li2CO3 and oxalic acid as raw materials, and then olivine-type LiFe1-3y/2AlyPO4 were synthesized by the following heat treatment. The samples were characterized by using X-ray diffraction, scanning electron microscope, high resolution transmission electron microscope and galvanostatic charge/discharge test. The results show that a proper amount of Al doping does not obviously change the structure of LiFePO4. When y=0.01, Al3+ ions tend to occupy Fe site, and when y≥0.02, Al3+ ions occupy both Fe and Li sites. LiFe0.985Al0.01PO4 exhibits the most impressive electrochemical performance as follows: its initial discharge capacities are 162.4, 152.2 and 142.0 mA？h/g at 0.1C, 1C and 2C rates, respectively, its discharge capacity is 149.7 mA？h/g even after 100 cycles at 1C rate.
Key words: cathode material; lithium iron phosphate; Al3+ doping; ball milling; room temperature reduction
