Highly Uniform MnCo2O4 Hollow Spheres‐Based All‐Solid‐State Asymmetric Micro‐Supercapacitor via a Simple Metal‐Glycerate Precursor Approach

Developing a high‐energy‐density all‐solid‐state asymmetric micro‐supercapacitor (AMSC) still remains a big challenge. Herein, a simple metal‐glycerate precursor strategy is used for the synthesis of highly uniform MnCo 2 O 4 hollow spheres, and the all‐solid‐state AMSC is fabricated by MnCo 2 O 4 hollow spheres. It is found that the MnCo 2 O 4 hollow sphere electrode processes a high specific capacitance (0.80 F cm −2 ) at 2 mA cm −2 and an excellent cycling stability (99% capacitance retention after 2000 cycles). The as‐fabricated all‐solid‐state AMSC displays a high energy density of 0.052 mWh cm −3 , a high power density of 320 mW cm −3 , and a long cycling life (95.7% capacitance retention after 10 000 charge/discharge cycles). In addition, the all‐solid‐state AMSC can be easily assembled in series to achieve a desirable output voltage, which can drive a light‐emitting diode. This work demonstrates that the MnCo 2 O 4 hollow spheres can be a promising electrode material for a stable, high‐energy‐density micro‐supercapacitor (MSC).