大倍率二氧化硅/碳复合材料的制备及电化学性能表征

Preparation and Electrochemical Properties Characterization of High-rate SiO_2/C Composite Materials

为了满足新能源储能及电动汽车对锂离子电池持续快速充电、慢速放电性能的要求,以正硅酸乙酯为二氧化硅前驱体,在两亲性炭材料(ACM)与聚乙二醇400(PEG400)形成的氢键限域体系中制备了大倍率二氧化硅/碳复合锂电负极材料(SiO_2-130/C)。材料表征结果表明,二氧化硅的粒径由500nm(未限域)降低到130nm(限域),同时,富碳的ACM在二氧化硅纳米颗粒表面构建了导电性良好的碳框架。在0.1A·g^(-1)和1A·g^(-1)的电流密度下,SiO_2-130/C的可逆比容量分别为527mAh·g^(-1)和347mAh·g^(-1),且在1A·g^(-1)的电流密度下连续400个充放电循环后,仍具有483 mAh·g^(-1)的可逆比容量,表现出优异的倍率性能及稳定的电化学性能。

High-rate SiO 2/C composite(called SiO 2-130/C)was synthesized using tetraethyl orthosilicate(TEOS)as SiO 2 precursor in a amphiphilic carbonaceous material(ACM)-polyethylene glycol 400(PEG 400)mixture.Confinement effect of smaller cells formed by ACM and PEG 400 on diameter of SiO 2 was studied.The results showed that the diameter of SiO 2 nanospheres was reduced from 500 nm(without confinement effect)to 130 nm(with confinement effect),and carbon framework resulting from carbon-rich ACM was constructed on the surface of SiO 2.Electrochemical performance of SiO 2-130/C composite was evaluated as anode material for lithium ion batteries.The reversible capacities of the SiO 2-130/C composite were 527 mAh·g-1 and 347 mAh·g-1 at current densities of 0.1 A·g-1 and 1 A·g-1,respectively.Moreover,the SiO 2-130/C composite,after the process of electrochemical activation,exhibited reversible capacitance as high as 483 mAh·g-1 at a current density of 1 A·g-1 over 400 cycles,indicating great rate performance and long-term cycling stability of the as-prepared SiO 2-130/C composite.