Porous engineering of CoS 2 /N-doped carbon polyhedra anode for durable lithium-ion battery.

In this work, the porous CoS 2 /N-doped carbon polyhedra (P-CoS 2 /CP) has been developed by employing ZIF-67 as the template for durable lithium-ion battery anode. The as-prepared P-CoS 2 /CP exhibits the novel dodecahedron structure filling with nanopores and CoS 2 nanoparticles. As compared to CoS 2 /CP (122 m 2 g -1 ), the P-CoS 2 /CP possesses the higher specific surface area of 367 m 2 g -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 CoS 2 nanoparticles are firmly wrapped by the carbon skeleton which can effectively suppresses the volume expansion of CoS 2 during the charging/discharging process. Besides, the N-doping enable to improve the conductivity of CP. As a result, the initial discharge capacity of P-CoS 2 /CP at 0.1 A g -1 is 1484.7 mAh g -1 with 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 -1 can still be achieved, realizing the good rate capability. The superior Li + performance of P-CoS 2 /CP is attributed to the synergistic effect of the unique multi-space structure and the high chemical activity of CoS 2 . Moreover, the Li + diffusion coefficient of P-CoS 2 /CP is 4.52 × 10 -6  to 1.98 × 10 -11 cm 2 s -1 , which is higher than that of CoS 2 /CP (1.45 × 10 -9  to 5.23 × 10 -11 cm 2 s -1 ), highlighting the significance of porous engineering.