Highly ordered mesoporous spinel ZnCo2O4 as a high-performance anode material for lithium-ion batteries

Abstract

Highly-ordered mesoporous spinel ZnCo2O4 (HOM-ZnCo2O4) with controlled morphology, high surface area and narrow pore size distribution is prepared through a facile infiltration route with molecular sieve SBA-15 as templates for the first time. At the same time, nanostructured porous spherical spinel ZnCo2O4 (NPS-ZnCo2O4) framework is also synthesized using silicon spheres as templates. HOM-ZnCo2O4 is revealed to have a highly ordered mesoporous structure with a pore diameter of ∼4nm and a high surface area of 112.0m2g−1, while NPS-ZnCo2O4 is a framework containing 3D connected pores with a diameter of ∼100nm and surface area of 88.4m2g−1. As the anode material, HOM-ZnCo2O4 displays a high reversible specific capacity up to 1623mAhg−1, ∼300mAhg−1 larger than NPS-ZnCo2O4 (1286mAhg−1), at a current density of 2.0 Ag−1. When applying a high current density of 8.0Ag−1, the capacity of HOM-ZnCo2O4 still remains at a high level of 1470mAhg−1, but NPS-ZnCo2O4 undergoes a severe degradation to 751mAhg−1. The large specific surface area contributes much to the better rate performance of the former because it provides a larger cross section for Li+ flux. Also, the small pore size may be more in favor of maintaining the structural stability of porous spinel material than the large one. Aside from its nanostructured characteristics, an inner atomic synergistic effect within the cubic lattices may account for the superior electrochemical performance of HOM-ZnCo2O4. HOM-ZnCo2O4 that exhibits high capacities and well stability is a kind of competitive anode materials and highly-ordered mesoporous structure is superior in electrode design.