不同碳源对碳热还原法合成Li_2FeSiO_4/C电化学性能的影响

Influence of different carbon sources on the electrochemical performance of Li_2FeSiO_4/C synthesized by carbothermal reduction method

以Li2CO3为锂源、Fe2O3为铁源、Si(OCH2CH3)4为硅源、羟乙基纤维素和蔗糖分别为碳源,采用碳热还原法制备了Li2FeSiO4/C锂离子电池复合正极材料,考察了羟乙基纤维素和蔗糖分别作为碳源对合成的Li2FeSiO4/C电化学性能的影响。结果表明:当烧结温度为600℃、烧结时间为10 h时,由羟乙基纤维素作为碳源制备的Li2FeSiO4/C样品在1.5～4.7 V、0.2C和20℃时的首次放电比容量为113.6 mAh/g,20次循环后放电比容量仍保持在102.3 mAh/g。较之蔗糖碳源样品,颗粒更小、分布更均匀,其电荷转移阻抗减小了80%、锂离子扩散系数增加了20%。

Li2FoSiO4/C composite cathode materials were prepared by carbothermal reduction method using hydroxyethylcellulose （HEC） and sucrose as carbon source respectively while using Li2CO3, Fe203 and Si（OC2H5）4 as raw materials. The influence of HEC and sucrose used as carbon source on the electrochemical properties of Li2FeSiO4/C was examined. The results demonstrate that the initial discharge specific capacity of Li2FeSiO4/C composite cathode material is 113.6 mAh/g at 0.2C and a potential range of 1.5-4.7 V （vs. Li/Li^＋） at room temperature when the Li2FeSiO4/C composite cathode material is prepared with HEC as carbon source and calcined at 600 ℃ for 10 h, the discharge specific capacity maintained 102.3 mAh/g after 20 cycles. The sample prepared from HEC as carbon source has smaller particle size and more uniform distribution than the sample prepared from sucrose, the charge transfer resistance of the samples using HEC as carbon source decrease 80%, meanwhile, the lithium ion diffusion coefficient increase by 20%.