双金属负载碳包覆SiO2负极材料的制备与研究

Preparation and research of bimetal-loaded carbon-coated SiO2 anode materials

  • 摘要: 二氧化硅(SiO2)作为锂离子电池负极材料,具有较高的理论放电比容量(1 965 mAh/g)和极低的成本,然而较高的氧含量导致SiO2的电化学活性较差。为解决其电化学活性低的问题,本文采用溶胶-凝胶法,以十六烷基三甲基溴化铵(CTAB)为模板,以硅酸四乙酯(TEOS)为原料,设计并制备了一种含介孔、颗粒尺寸约为100 nm的SiO2颗粒,以间苯二酚-甲醛树脂(RF)为碳前驱体对制备的SiO2颗粒进行了包覆处理。并在上述实验的基础上,通过络合反应将Cu2+、Fe3+掺入树脂层,高温碳化后形成双金属负载碳包覆材料SiO2@Cu-Fe-C,双金属负载产生的协同效应有效提升了材料的电化学性能。数据表明:SiO2@Cu-Fe-C的首次库仑效率(ICE)为52.2%,在200 mA/g的电流密度下表现出719 mAh/g的高可逆放电比容量,在1 000 mA/g的电流密度下循环500圈能保持570 mAh/g的平均放电比容量。

     

    Abstract: Silicon dioxide (SiO2) is considered a promising anode material for lithium-ion batteries due to its high theoretical specific discharge capacity (1 965 mAh/g) and extremely low cost. However, its high oxygen content leads to poor electrochemical activity. To address this issue, a mesoporous SiO2 with a particle size of approximately 100 nm was designed and prepared via the sol-gel method, using tetraethyl orthosilicate (TEOS) as the precursor and cetyltrimethylammonium bromide (CTAB) as the template. The prepared SiO2 particles were subsequently coated using resorcinol formaldehyde resin (RF) as the carbon precursor. Based on the above experiments, Cu2+ and Fe3+ were doped into the resin layer through a complexation reaction. After high-temperature carbonization, a bimetal-loaded carbon-coated material, SiO2@Cu-Fe-C, was formed. The synergistic effect generated by the bimetallic loading effectively improved the electrochemical performance of the material. The data showed that the initial Coulombic efficiency (ICE) of SiO2@Cu-Fe-C was 52.2%. It exhibited a high reversible specific discharge capacity of 719 mAh/g at a current density of 200 mA/g, and maintained an average specific discharge capacity of 570 mAh/g at a current density of 1 000 mA/g after 500 cycles.

     

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