Facile Synthesis of Highly Uniform ZnMn2O4 Hollow Nanospheres with Excellent Lithium Storage Properties

Hollow nano/micron-structured transition metal oxides (TMOs) hold great potential as electrodes for rechargeable batteries, due to abundant electrochemically active sites, shortened ion diffusion length, and robust architecture. Herein, a facile solvothermal approach combined with post annealing is reported for synthesizing highly uniform ZnMn2O4 hollow nanospheres. The one-pot solvothermal reaction is the key step to form a hollow interior. With solvothermal reaction processing, the precursor solid nanospheres are formed firstly, which gradually evolve into core-shelled structures and finally hollow structures via a self-templated process. Then, the ZnMn2O4 nanospheres with well-inherited hollow interior are obtained by the thermal decomposition of precursors. When evaluated as an electrode, the ZnMn2O4 hollow nanospheres show lithium storage properties superior to solid counterparts, in view of high reversible capacity (735.0 mAh g(-1) after 200 cycles at 0.1 A g(-1)), and ultralong cyclic stability (up to 1000 cycles at 1 A g(-1)). A dominant pseudocapacitive contribution of 60.0% is identified for the ZnMn2O4 hollow electrode, leading to excellent rate performance. This work provides a new path for preparing TMOs with hierarchically hollow structure.