基于ZIF-8的三维网络硅碳复合材料锂离子电池性能研究

锂离子电池已广泛应用于各种便携式电子设备及新能源汽车等领域, 但随着电子设备的不断更新换代及电动汽车的快速发展, 理论比容量较低的传统石墨负极(372 mAh/g)已无法满足社会的需求。基于此, 本工作设计并制备了一种Zn基金属有机物框架(ZIF-8)衍生的三维网络状硅碳(Si@NC)复合材料用于锂离子电池性能研究。首先对纳米硅表面进行化学改性,然后在改性的硅表面原位生长ZIF-8小颗粒(Si@ZIF-8), 最后对Si@ZIF-8碳化得到Si@NC复合材料。研究表明, Si@NC复合材料的三维网络状多孔结构既可以很好地限制硅的体积膨胀, 又能极大地提升材料的电导率, 展现出稳定的循环性能和良好的倍率性能, 在5 A/g的大电流下能保持760 mAh/g的放电比容量。与商业三元正极材料组装的全电池也表现出较好的性能, 在0.4C (1C =160 mA/g)下循环50圈依然可以保持60.4%的比容量。这些研究结果说明该Si@NC复合材料具有较好的应用前景。

ZIF-8-derived Three-dimensional Silicon-carbon Network Composite for High-performance Lithium-ion Batteries

Lithium-ion batteries (LIBs) are widely applied to various portable electronic devices and new energy vehicles. However, the traditional graphite anode with low theoretical capacity (372 mAh/g) is unable to meet the need of the rapid development of economy and society. Herein, a zinc-based metallic organic framework (ZIF-8) derived three-dimensional network carbon coated silicon (Si@NC) composite was designed for lithium-ion battery. Firstly, the surface of nano-silicon was chemical modified; secondly, small size ZIF-8 was in situ grown on the silicon surface to form Si@ZIF-8; finally, the three-dimensional network Si@NC composite was obtained by carbonization. Results show that the three-dimensional network porous structure of the Si@NC composite not only limits the volume expansion of silicon, but greatly improves the conductivity of the materials, exhibiting excellent cycle stability and outstanding rate performance. As a result, a discharge specific capacity of 760 mAh/g is maintained at a high current density of 5 A/g. Using commercial material as cathode and Si@NC as anode, the assembled full LIBs demonstrate a capacity retention of 60.4% at 0.4C (1C =160 mA/g) for 50 cycles. These results indicate that the as-synthesized three-dimensional network porous structure of Si@NC composite has a potential practical application for LIBs.