Designed synthesis of yolk-shelled NiCo2O4/MnCo2O4 hollow sphere with boosted performance for supercapacitors

A simple etching and calcination strategy is developed for achieving NiCo 2 O 4 /MnCo 2 O 4 yolk-shelled hollow structure (YSHS), which perform excellent electrochemical performance in supercapacitors. • NiCo 2 O 4 /MnCo 2 O 4 yolk-shelled hollow structure is synthesized via etching and calcination route. • The synthesized NiCo 2 O 4 /MnCo 2 O 4 performs excellent performance in supercapacitors. • A solid-state asymmetric supercapacitor configured by NiCo 2 O 4 /MnCo 2 O 4 exhibits desired performance. Rational construct the micro architecture of electrode materials is verified as a feasible strategy for advancing the performance. Herein, controllable design of NiCo 2 O 4 /MnCo 2 O 4 yolk-shelled hollow sphere from Ni-Mn-Co glycerate is presented via etching and calcination methods. For comparison, utilizing the Ni-Mn-Co glycerate, NiCo 2 O 4 /MnCo 2 O 4 hollow and solid sphere are also achieved. Due to its distinctive textural with high surface area and mesoporous, the NiCo 2 O 4 /MnCo 2 O 4 yolk-shelled hollow sphere possesses a large specific capacitance (1636 F g -1 at 4.0 A g -1 ) and cycling durability (10% reduction over 6000 cycles at 15 A g -1 ) in comparison with hollow and solid structures. In-depth evaluating the practical application for supercapacitor, a solid-state asymmetric supercapacitor is designed with NiCo 2 O 4 /MnCo 2 O 4 yolk-shelled hollow sphere and active carbon. An energy density of 62.8 Wh kg -1 is obtained at 1650.4 W kg -1 , while retaining 23.2 Wh kg -1 even in larger 12367.7 W kg -1 . These results reveal that the NiCo 2 O 4 /MnCo 2 O 4 yolk-shelled hollow sphere is a promotion material for supercapacitor. This work is expected to be promoted the synthesis of hollow structured hybrid ternary oxides, which are regard as latent candidates for energy storage.