▎ 摘　　要

Recently, cobalt disulfide (CoS2) as a promising candidate of anode material for sodium ion batteries is paid much attention because of the high theoretical capacity. However, the poor rate capability and cycling stability are still the barriers to the large-scale application of CoS2 resulting from its low intrinsic electronic conductivity and severe volume change during the sodiation and desodiation process. In order to address above issues, herein, reduced graphene oxide (rGO) is introduced to define the CoS2 nanoparticles growth in the solvothermal synthesis process and construct the three-dimensional conductive network, which can tune the electronic conductivity, ionic diffusivity and inhibiting effect of volume change of CoS2/rGO composites anode material. It is found that these factors show different trends accompanying with the increase of rGO doping amount. The compact rGO network is beneficial to improve the electronic conductivity and hinder the volume change of the composites, however, it maybe does harm to the fast sodium ion diffusion. And when it becomes sparse, the opposite is true. Hence, a balanced strategy based on "bucket principle" is proposed to achieve the balanced enhancement of the rate capability and cycling performance. The optimized CoS2/rGO electrode acquires a superior performance, possessing 675.8 mAh g(-1) at 0.1 A g(-1) and 471.1 mAh g(-1) at 2.0 A g(-1) with the capacity retention of 69.7%, and it still has 272.5 mAh g(-1) after 500 cycles at 1.0 A g(-1) in the voltage range of 0.01-3.0 V. This can be attributed to the improvement of charge transfer process and the excellent accommodating capacity of volume change provided by rGO conductive network. This balanced strategy can also be used to synthesize high-performance composite materials in other fields. (C) 2022 Published by Elsevier B.V.