Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Jiangsu Engineering and Technology Research Center of Environmental Cleaning Materials, School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, No. 219, Ningliu Road, Nanjing 210044, China.
College of Engineering and Applied Sciences, Nanjing University, No.16, Jinyin Street, Nanjing 210093, China.
J Colloid Interface Sci. 2018 Dec 15;532:738-745. doi: 10.1016/j.jcis.2018.08.037. Epub 2018 Aug 12.
Silicon is one of the most promising candidates for anodes of lithium ion batteries attributed to the highest theoretical specific capacity (4200 mAh/g). However, the conductivity and structural integrity during the lithiation-delithiation process are very poor, which seriously affect the actual electrochemical performance. To address these issues, we introduce graphene framework as both structural skeletons and conductive networks for silicon in this work. Through a facile freeze-drying approach, Si nanoparticles are successfully anchored on graphene sheets uniformly, and graphene form strong and conductive framework, which serves as mechanical support, electrical network, and buffer layer for Si, highly improving the structural integrity and conductivity. The electrochemical examinations indicate that the synthesized graphene-Si aerogels can deliver 104% specific capacity retention after cycled for 195 times at 0.8 A/g. Multi-walled carbon nanotubes are utilized to improve the rate property, and the resulting anode exhibits average specific capacities of 1415, 1209, 1057, 888, 781, and 646 mAh/g at charge/discharge rates of 0.05 C, 0.18 C, 0.2 C, 0.5 C, 1 C, and 2 C, respectively. Benefit from the facile synthesis and excellent cycling stability, it is expected that graphene-Si aerogels may play an important role in lithium ion battery.
硅是锂离子电池阳极最有前途的候选材料之一，这归因于其最高的理论比容量（4200 mAh/g）。然而，在锂化-脱锂过程中，其电导率和结构完整性很差，严重影响了实际的电化学性能。为了解决这些问题，我们在这项工作中引入了石墨烯骨架作为硅的结构骨架和导电网络。通过简单的冷冻干燥方法，成功地将硅纳米颗粒均匀地锚定在石墨烯片上，并且石墨烯形成了强而导电的框架，充当了硅的机械支撑、电子网络和缓冲层，极大地提高了结构完整性和电导率。电化学测试表明，合成的石墨烯-硅气凝胶在 0.8 A/g 的电流密度下循环 195 次后，可保持 104%的比容量保持率。多壁碳纳米管被用来提高倍率性能，所得的阳极在 0.05 C、0.18 C、0.2 C、0.5 C、1 C 和 2 C 的充放电速率下，分别表现出 1415、1209、1057、888、781 和 646 mAh/g 的平均比容量。由于其简便的合成和优异的循环稳定性，预计石墨烯-硅气凝胶在锂离子电池中可能发挥重要作用。
