Mixed analogous heterostructure based on MXene and prussian blue analog derivative for high-performance flexible energy storage

•A 2D MXene wrapped Ni-Fe oxide nanocube based flexible electrode was synthesized.•The composite film functioned like a mixed analogous heterostructure.•The film successfully combined the advantages of different components.•The film demonstrated satisfied electrochemical performance and flexibility. In this work, we addresses the fabrication of a flexible film electrode based on 2D MXene wrapped 3D Ni-Fe oxide nanocube mixed analogous heterostructure. The resulted composite film electrode successfully inherits the merit of different building blocks: MXene layers works as binders and conductive additives that can connect cubic Ni-Fe oxide nanoparticals, facilitate the charge transfer and avoid a significant conductivity decrease in the resulting electrode. While cubic Ni-Fe oxide serves as an active spacer inside the adjacent MXene layers to increase the interlayer space, facilitate the electrolyte diffusion and enhance the electrochemical activity of the composite film. As a result, the optimized composite film manifests excellent specific capacitance of 1038.43 mF cm−2 at current density 0.5 mA cm−2. Meanwhile by assembling into all-solid-state flexible supercapacitor, an excellent specific areal capacitance of 328.35 mF cm−2 at 0.2 mA cm−2 was achieved. Additionally, the excellent energy storage performance is well maintained with a capacitance retention of 90.9% during 10,000 charging-discharging long cycles. Furthermore, a high mechanical robustness with 88.9% capacitance remained after subjected to bending at 90° for 50 cycles, suggesting great potentials for the applications in future flexible and wearable devices.