(浙江大學(xué) 材料科學(xué)與工程學(xué)系，杭州310027)
摘 要: 以FePO4為鐵源、Li2CO3為鋰源、聚丙烯為還原劑和碳源，采用一步固相法合成原位碳包覆磷酸亞鐵鋰(LiFePO4/C)復(fù)合材料，研究合成溫度對(duì)材料LiFePO4/C復(fù)合材料電化學(xué)性能的影響。采用X射線衍射、掃描電鏡和拉曼光譜技術(shù)對(duì)合成產(chǎn)物的晶體結(jié)構(gòu)、表面形貌和碳結(jié)構(gòu)進(jìn)行表征，通過電化學(xué)阻抗譜(EIS)和充放電測(cè)試對(duì)材料的電化學(xué)性能進(jìn)行測(cè)試和分析。結(jié)果表明：在600~750 ℃溫度范圍內(nèi)都可合成純LiFePO4/C復(fù)合材料，隨著合成溫度的升高，材料顆粒尺寸和石墨化程度都將增大；600 ℃保溫8 h合成的材料顆粒尺寸為100~500 nm，其1 C放電比容量達(dá)到144.2 mA∙h/g，5 C放電比容量達(dá)到119 mA∙h/g。
關(guān)鍵字: LiFePO4/C；鋰離子電池；正極材料
（Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China）
Abstract:LiFePO4/C composites were synthesized by one-step solid-state reaction using FePO4 and Li2CO3 as raw materials and polypropylene as reductive agent and carbon source. The effect of synthesis temperature on the electrochemical performances of LiFePO4/C composites was studied. The microstructure, morphology of the products and the structure of carbon were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and Raman microprobe spectra. The electrochemical impedance spectroscopy (EIS) and charge-discharge test were used to study their electrochemical performances. The results show that LiFePO4/C composites can be synthesized in the temperature range from 600 to 750 ℃. The size of the particle and the degree of graphitization increase with increasing synthesis temperature. The size of LiFePO4/C composites synthesized at 600 ℃ for 8 h is about 100−500 nm, and it has discharge capacities of 144.2 and 119 mA∙h/g at 1 C and 5 C rates, respectively.
Key words: LiFePO4/C; lithium ion batteries; cathode materials
