In situ polymerization of aniline to prepare porous micro-nanostructure anode of graphene wrapping silicon and polyaniline for lithium ion batteries

Due to the high theoretical specific capacity, silicon materials have been developed worldwide to meet the requirement of energy storage in lithium ion batteries. But the low conductivity and large volume expansion (300%) of Si usually cause poor cycling stability during charge/discharge processes. Here, a novel approach to fabricating a porous micro-structure of graphene wrapping silicon nanoparticles and polyaniline skeleton is proposed. The polyaniline skeleton grafted silicon nanoparticles is obtained by an in situ polymerization and the graphene sheets further wrap on the skeleton owing to an enhancement of π conjugation between the polyaniline and graphene. Thus, a 3D conductive and porous micro-structure is synthesized, which not only facilitates the electron and lithium ion transfer but also enhances the stability of structure during the volume expansion of Si. Benefiting from the advantages of structure, the electrode can deliver a reversible specific capacity of 2473 mAh g−1 at 0.2 A g−1 and 958 mAh g−1 at 10 A g−1. The electrode can keep a stable cycling with a capacity retention of 70% and 60% for 100 and 200 cycles at 25 °C, respectively. The method provides a promising strategy for solving the issues of silicon in lithium ion batteries.