Co.sub.3O.sub.4-C yolk-shell hollow spheres derived from ZIF-12-PVP@GO for superior anode performance in lithium-ion batteries

Transitional metal oxides have attracted increasing attention as the most promising anode material for lithium-ion batteries (LIBs). However, due to the poor ionic conductivity and great structural changes in the process of Li.sup.+ insertion and extraction, the performance of the pristine materials in batteries still has a far way to go to satisfy requirements. In this article, using spherical ZIF-12 as a pyrolysis precursor, two Co.sub.3O.sub.4 hollow core-shell carbon nanocomposites (CHS@C and CHS@CG) were fabricated via a molecular precursor pyrolysis strategy. The synergistic effect of the yolk-shell hollow nanosphere structure shortens the diffusion path of ions, increases the contact area between the electrode and electrolyte, and provides a buffer space for the volume change in the electrochemical reaction. Both materials have excellent structural stability and good electrical conductivity. In comparison, the performance of CHS@CG is better, and the reversible specific capacity reaches 831 mAh·g.sup.-1 at 0.2 C after 400 cycles. In the galvanostatic charge-discharge process, the Coulombic efficiency reaches nearly 100%, exhibiting a good reversible cycle. The synthesis method of these electrode materials can provide a reference for making other energy storage equipments.