(蘇州大學(xué) 沙鋼鋼鐵學(xué)院，蘇州 215021)
摘 要: 采用共沉淀法制備摻Al3+前驅(qū)體FePO4·2H2O，并以乙二酸為還原劑，與Li2CO3反應(yīng)在常溫下球磨合成LiFePO4前驅(qū)混合物，后經(jīng)熱處理得到橄欖石型LiFe1-3y/2AlyPO4。用XRD、SEM、HRTEM和恒流充放電等對樣品進行表征。結(jié)果表明：適量Al3+摻雜不會破壞 LiFePO4的晶體結(jié)構(gòu)，當(dāng)摻雜量較低時(y=0.01)，Al3+優(yōu)先占據(jù)Fe位；當(dāng)摻雜量較高時(y≥0.02)，Al3+同時占據(jù)Li位和Fe位。電化學(xué)測試表明：LiFe0.985Al0.01PO4擁有最優(yōu)的電化學(xué)性能，該樣品在0.1C、1C和2C倍率下的首次放電比容量分別為162.4、152.2和142.0 mA？h/g，在1C倍率下循環(huán)100次后的放電比容量高達149.7 mA？h/g。
關(guān)鍵字: 正極材料；磷酸鐵鋰；Al3+摻雜；球磨；常溫還原
（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
