Hard carbon has become the commercial anode material of sodium ion battery

supporting the large-scale energy storage application in electric power system. However

the formation mechanism of three-dimensional disordered graphene networks and sodium storage behavior of hard carbon remains still elusive. This research integrates the ReaxFF with Arrhenius theory

and meanwhile employs the general protocol of liquid quenching and annealing to construct a series of large-scale molecular models of hard carbon. The impacts of the annealing time and temperature on structure are revealed. The results show that

at the highest temperature of 4 000 K and time for 1 ns

the sp2 hybridization fraction of hard carbon reaches 96.8 %

with hexagonal rings of per atom as 0.42. Afterwards

the discharge process of hard carbon anode under sodium insertion is disclosed by means of GCMC-MD

uncovering changes in the Young's modulus

ultimate strength

and yield strength under various sodiation states. The research finds that with the continuous sodium storage

the mechanical property of hard carbon anode reduces obviously

exhibiting macroscopic sodium creep behavior

consistent with the experimental observations. Finally

this research can enhance the insight of the relationship between microstructure and macroscopic performance of hard carbon anode

and provide the theoretical support for designing the electrode material.