Preparation of porous carbon spheres and their application as anode materials for lithium-ion batteries: A review

To meet the energy storage requirements for portable electronic devices, electric vehicles, renewable-coupled smart grids and more, it is imperative to develop lithium-ion batteries (LIBs) with increased energy densities. Among various factors, the development of effective electrode materials plays a critical role on the performance and applications of next-generation LIBs. Porous carbon spheres have excellent intrinsic advantages, such as high chemical stability, high electrical conductivity, a uniquely high specific surface area and connected porous structure. Furthermore, the morphology, porosity, and composition of porous carbon spheres are easily tunable. These properties render porous carbon spheres effective to transfer electrons and ions in electrodes. Moreover, the carbon skeleton exhibits little volumetric change during the process of inserting and extracting lithium ions. Therefore, porous carbon spheres have attracted extensive research interest to apply as anode materials for LIBs. In this review, various preparation methods for porous carbon spheres are introduced. Strategies to improve the performance of LIBs anode materials are also described, including heteroatom doping in porous carbon and structural hybridization with high specific capacity materials (carbon nanotubes, graphene oxide, Group IV elements, metal oxides, sulfides, etc.). The structure-performance relationship of porous carbon spheres with various morphologies and surface properties applied as LIBs anode materials are also discussed. Finally, the advantages, challenges and opportunities of porous carbon spheres as LIBs anode materials are described. This review is to provide a reference for promoting the rational development of carbon-based electrodes for next-generation LIBs with high performance.