Tunable synthesis of bimetallic hybrid multishelled hollow structure for high-performance aqueous alkaline batteries

Abstract

Multishelled hollow structure (HoMS) with various metal components show alluring prospect due to the combined effects of various elements. But due to the different condensation and hydrolysis rates of different metal oxide precursors it is still a big challenge to synthesize multicomponent HoMSS. Here we report two different strategies: 1.Two-step strategy (TsS) and 2. One-step strategy (OsS) for the tunable synthesis of HoMSS with two transition metal oxide precursors (zinc chloride and titanium chloride) by using carbon microspheres as a hard template. As a result a number of crystalline mesoporous HoMSs of ZnO@TiO2 with varied thicknesses, high porosity, large specific surface area and different voids are synthesized. Synthesis strategies and conditions not only affect the shell numbers, thickness of the shell, pore size, surface area and size of the voids but also the amount of absorbed metal ions (Zn2+ and Ti4+) varied. We compared their performances as cathode in aqueous alkaline battery and found that the ZnO@TiO2 HoMSS synthesized by OsS (triple shelled) exhibit excellent high potassium storage capacity, good rate capability, outstanding reversibility, and steady long cyclic life. The thinner shell, larger pore size, high surface area, and bigger voids contribute a distinctive buffering zone for charge-discharge, thus improving the structural stability and enhance the cycling stability during OH intercalation/de-intercalation process. ZnO@TiO2 triple shelled HoMSS with large pore size and big voids delivers a high discharge specific capacity of 260 mAhg−1 at a current density of 1 Ag−1, and capacity enhanced to 270 mAhg-1 over 1000 cycles.