Research On Synthesis And Electrochemical Performance Of Graphene Quantum Dots Docorated Free-standing Bismuth Oxide Electrode

Portable electronic devices follow the trend toward small, lightweight and even collapsible characteristics to meet the rapidly growing demands for modern market. The emergence of increasingly prevalent flexible products such as flexible displays and curved smartphones implies that flexible devices are stepping into the mainstream of electronics. The endurance capacity of portable electronic devices has been people’s focus of attention. Lithium ion batteries（LIBs） have been considered to be one of the most important portable energy storage systems due mainly to its large energy density. Besides capacity, the cycling stability is also a crucial factor for portable applications. Bi₂O₃ is a novel promising anode material for LIBs which possesses a relatively high theoretical discharge capacity of 690 mA h g-1. However, the study on Bi₂O₃ is only few efforts.In this work, we fabricated a carbon cloth based Bi₂O₃ anode. Graphene quantum dots（GQDs） were also introduced for a better material performance. To our knowledge, this is the first report on a Bi₂O₃-based flexible electrode for LIBs.The influence of different reaction conditions on the growth of Bi₂O₃ is examined and discussed. We found the growth is very sensitive to temperature and can form uniform structure only at 160 ℃. Array of Bi₂O₃ can only form after 5 h and the increasing of Bi3+ concentration contributes to the reduction of large aggregates. Optimal condition of preparation was determined and fixture tools were innovatively proposed to improve the morphology. The array of thin petals and large surface area imply a high diffusion rate of lithium ion as well as excellent volume expansion accommodation ability.Graphene quantum dots were made and introduced for a better material performance. The GQDs decorated Bi₂O₃ anode had a capacity of 923 mAh g-1 after 150 cycles at a current density of 1200 m A g-1. Surface coating of GQDs afforded avoidance of active material fracture and pulverization. The uniform distribution of GQDs on Bi₂O₃ can not only inhibit the agglomeration of Bi₂O₃ sheets but also reduce the dissolution of active materials, results in better interface quality and cycling perdurability.