A review study on the recent advances in developing the heteroatom-doped graphene and porous graphene as superior anode materials for Li-ion batteries

Graphene materials, with their distinctively fascinating physicochemical properties, have been receiving great attention as favorable anode materials for use in Li-ion batteries (LIBs). However, the high affinity of graphene nanosheets to restack and agglomerate during electrode assembly reduces the deliverable specific capacity due to the limited available surface area and active sites for Li-ion storage. Furthermore, the high aspect ratio of graphene nanosheets could result in long transport pathways for Li-ions and consequently limiting the rate performance. These drawbacks can be significantly improved via the functionalization of graphene by various heteroatoms and also the formation of porous graphene, adding unique beneficial properties to the inherent characteristics of graphene. Here, a comprehensive review of porous and/or heteroatom doped graphene anode materials for LIBs is presented, which summarizes in detail the main recent literature from their procedure, optimum synthesis parameters, relevant mechanisms, and the obtained morphology/structure to their electrochemical performance as the LIBs anode. Finally, the research gaps are proposed. This review will promote the basic understanding and further development of porous and/or doped graphene materials as anodes for LIBs.