GRAPHENE NANOSHEETS-BASED NANOCOMPOSITES AS ANODE MATERIALS FOR LITHIUM ION BATTERIES

摘要

Rechargeable lithium ion batteries are amongst the most promising candidates in terms of energy storage systems. High energy capacity and long cycle life are indispensable for these portable electronic devices [1]. Silicon has a low discharge potential and the highest known theoretical capacity (4200 mAh g~(-1)), which has long been considered as an ideal anode materials for next generation lithium ion batteries [2]. However, this material suffers from serious irreversible capacity and poor cycling stability, which result from more than 300 % volume change during lithium ion insertion/extraction process [3]. Another kind of anode materials, TiO2 is an abundant, low cost, and environmentally benign materials, and its lattice charges is negligible during Li ion intercalation or de-intercalation for good stability and long cycle life. The shortcoming of this materials is low conductivities and slow lithium ion diffusion [4]. Graphene nanosheets have the advantages of high specific surface area, high electric conductivity and flexibility [5] and it is adopted here as a 3D conducting network and nanoreactors for the Si and TiO2 anode materials to enhance the storage capacity and cyclic stability.