C3N monolayer with substitutional doping and strain modulation serving as anode material of lithium-ion batteries

Two-dimensional (2D) materials have been proved to be very promising anode materials of many kinds of batteries, including lithium-ion batteries (LIBs). The graphene-like carbon-nitrides with lightweight nature have received intense attention. The polyaniline (C3N) multilayer has shown its capabilities in LIBs, but C3N mono-layer delays its arrival at application owing to too weak lithium (Li) adsorption. In this study, for the first time, the application of C3N mono-layer as anode material for LIBs is realized by introducing heteroatom doping (B, O and S) based on first-principles simulations. The O-doped C3N (O-N-C3N) offers Li storage capacity of 534.42 mAh g(-1), low open circuit voltage (OCV) of 0.02 V, low Li adsorption energy of -3.64 eV and single Li atom migration energy barrier of 0.78 eV. Moreover, S-N-C3N can dramatically lower the migration barrier of Li (0.12 eV) with respect to that on pristine C3N (0.41 eV). Further calculations show that the Li adsorption on C3N can be enhanced and migration barrier will decrease through the application of strain. This work demonstrates that heteroatom doping coupled with strain modulation is proved to be an effective and feasible strategy for the design of high-performance carbon-based 2D anode materials of batteries.