Achieving ultrahigh-energy-density in flexible and lightweight all-solid-state internal asymmetric tandem 6.6 V all-in-one supercapacitors

Internal asymmetric tandem supercapacitors with wide working voltage have drawn an increasing attention to develop high-energy-density supercapacitors. However, the small specific capacitance and low working voltage of single-supercapacitor restrict further improvement of their energy density. A rational solution to this restriction would be to synthesize high-performance electrode materials. Accordingly, this work specifies a simple and cost-effective method to directly grow manganese dioxide and vanadium nitrogen nanosheets on zeolitic imidazolate framework-67 derived N-doped carbon conductive skeletons. These well-designed core-shell pseudocapacitive materials integrate the features of large specific surface area, rich reaction sites, high mass loading, short electron/ion diffusion paths and remarkable conductivity, affording prominent electrochemical performance. Furthermore, a flexible all-solid-state internal asymmetric tandem 6.6 V all-in-one supercapacitor was successfully assembled by matching as-fabricated cathode and anode materials as well as using carbon nanotube film as a lightweight current collector. The resulting all-in-one devices exhibited a high specific capacitance of 336.7 mF/cm2 (19.6 F/cm3) and an exceptional energy density of 2032.8 μWh/cm2 (118.2 mWh/cm3) and thus substantially outperform most previously reported state-of-the-art asymmetric supercapacitors. Our work provides a promising strategy for the rational construction of high-performance, inexpensive and safe all-in-one supercapacitors for next-generation portable and wearable electronic devices.