Sulphonated graphene-encapsulated Fe2N in the PANI matrix as a high performance lithium ion battery anode

Abstract

This study demonstrates the development of a promising heterostructure anode by a facile synthetic strategy of fabricating Fe2N in the scaffold of sulfonated graphene oxide (SGO) embedded in a polyaniline (PANI) matrix. The hierarchically nanostructured anode material consolidates the high theoretical capacity, multielectron transfer capability, and high ionic diffusivity of Fe2N with the high conductivity and mechanical flexibility of the graphene framework. The PANI matrix serves not only as a glue to combine the Fe2N and SGO sheets but also provides additional conductivity, mechanical strength, and stability. The assembled heterostructure Fe2N-SGO/PANI-24 h delivers a reversible capacity of 864.1 mAh/g after 500 cycles, with an initial discharge capacity of 1204.8 mAh/g at a current density of 0.05 A/g, which is superior to the constituent components and other counterparts at the same current density. The pronouncedly enhanced performance of Fe2N-SGO/PANI-24 h compared to pristine Fe2N reveals that the PANI matrix and SGO boosted the capacity, buffered the volume variations, and kept the overall conductivity of the electrode during successive charge-discharge cycles. Furthermore, increasing the reaction time helped in the uniform distribution of Fe2N-SGO in the PANI matrix, which improves the overall performance.