Construction of in-plane 3D network electrode strategy for promoting zinc ion storage capacity

The energy density and mechanical flexibility of the reported zinc ion microcapacitors (ZIMCs) require further improvement to meet the rapid development and modularization of miniaturized and self-powered electronic systems. Herein, a flexible ZIMC with composite "honeycomb" three-dimensional (3D) network structure was creatively assembled using a low-cost blade-coating and foaming technique. MnO2 and MXene uniformly coating onto this 3D network structure with in-plane open-holes were used as the cathode and anode, respectively. The unique configuration endows the electrodes with large specific surface area, more loading active materials and fully exposed active sites, which is conducive to electrons and ions transport and electrolyte penetration. And the specific capacitance of ZIMC can reach up to 264 mF cm−2, energy density with 132 μWh cm−2, power density with 1510 μW cm−2. In addition, this composite "honeycomb" 3D network structure displays excellent mechanical property with tensile stress of 19.33 MPa and strain of 4.52%, which can buffer volume changes and enhance the structural stability of the device (the capacitance retention over 90% after 6700 cycles). Therefore, the development of electrode materials for ZIMC with this reliable and stable 3D network structure has great potential in the field of wearable electronics.