Porous engineering of CoS2/N-doped carbon polyhedra anode for durable lithium-ion battery

In this work, the porous CoS2/N-doped carbon polyhedra (P-CoS2/CP) has been developed by employing ZIF-67 as the template for durable lithium-ion battery anode. The as-prepared P-CoS2/CP exhibits the novel dodecahedron structure filling with nanopores and CoS2nanoparticles. As compared to CoS2/CP (122 m2g-1), the P-CoS2/CP possesses the higher specific surface area of 367 m2g-1, which benefits to enlarge the electrode-electrolyte contact area and promote the Li+diffusion dynamics at high current density. On the other hand, the CoS2nanoparticles are firmly wrapped by the carbon skeleton which can effectively suppresses the volume expansion of CoS2during the charging/discharging process. Besides, the N-doping enable to improve the conductivity of CP. As a result, the initial discharge capacity of P-CoS2/CP at 0.1 A g-1is 1484.7 mAh g-1with the coulombic efficiency of 48.9%. After 100 cycles, the reversible capacity stabilized at 726.2 mAh g-1. Even the current density increases to 2.0 A g-1, a high reversible capacity of 353.7 mAh g-1can still be achieved, realizing the good rate capability. The superior Li+performance of P-CoS2/CP is attributed to the synergistic effect of the unique multi-space structure and the high chemical activity of CoS2. Moreover, the Li+diffusion coefficient of P-CoS2/CP is 4.52 × 10-6 to 1.98 × 10-11cm2s-1, which is higher than that of CoS2/CP (1.45 × 10-9 to 5.23 × 10-11cm2s-1), highlighting the significance of porous engineering.