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.