Nanocarbon/Metal Oxide Hybrids for Lithium Ion Batteries

The requirement of long cycle life, high energy density, and green energy storage solutions in the modern society stimulates intensive research of new electrode materials for lithium ion batteries (LIBs). Metal oxides (MOs) have aroused wide interests as novel electrodes for LIBs due to their high theoretical capacity. However, their applications in practical LIBs are significantly hindered by the low initial Coulombic efficiency and poor cyclic performance arising from huge volume expansion and severe aggregation during the charge/discharge processes. To solve these problems, nanocarbon materials, including carbon nanocoating, carbon nanofibers, carbon nanotubes, graphene, and hierarchical carbon nanostructures, have been widely introduced to form nanocarbon/MO hybrid electrodes. The design and preparation of various nanocarbon/MO hybrid electrodes and their applications in high performance LIBs are reviewed in this chapter. In these hybrid structures, synergistic effects could be obtained between carbon nanostructures and MOs. Nanocarbon materials confine the nucleation and growth of MOs, function as conductive backbone for electron transport, and provide buffer for volume change of MO electrodes. Meanwhile, nanoscale MO helps to suppress the aggregation of carbon nanotubes or the restacking of graphene and alleviate the loss of effective surface area of carbon materials. Due to such synergistic effects, the nanocarbon/MO hybrid materials deliver increased capacity and Coulombic efficiency, improved cycle performance and rate capability, and higher energy/power densities. Challenges still remain including the development of advanced material-processing methods for large-scale production, investigation on the surface chemistry of the nanocarbon/MO hybrid materials, fabrication of thin and flexible electrodes for compact high-power and high-energy LIBs, and so on. Although facing these challenges, nanocarbon/MO hybrid electrodes are still one of the most exciting material systems for energy and environmental studies. Their large-scale applications in LIBs may be achieved in the near future and open up more opportunities in human life.