2D MXene materials are of considerable interest for future energy storage. A MXene film could be used as an effective flexible supercapacitor electrode due to its flexibility and, more importantly, its high specific capacitance. However, although it has excellent electronic conductivity, sluggish ionic kinetics within the MXene film becomes a fundamental limitation to the electrochemical performance. To compensate for the relative deficiency, MXene films are frequently reduced to several micrometer dimensions with low mass loading (<1 mg cm−2), to the point of detriment of areal performance and commercial value. Herein, for the first time, the design of a 3D porous MXene/bacterial cellulose (BC) self‐supporting film is reported for ultrahigh capacitance performance (416 F g−1, 2084 mF cm−2) with outstanding mechanical properties and high flexibility, even when the MXene loading reaches 5 mg cm−2. The highly interconnected MXene/BC network enables both excellent electron and ion transport channel. Additionally, a maximum energy density of 252 µWh cm−2 is achieved in an asymmetric supercapacitor, higher than that of all ever‐reported MXene‐based supercapacitors. This work exploits a simple route for assembling 2D MXene materials into 3D porous films as state‐of‐the‐art electrodes for high performance energy storage devices.

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The dynamics of a number of switching circuits can be represented by one-dimensional (1-D) piecewise smooth maps under discrete modeling. In this paper we develop the bifurcation theory of such maps and demonstrate the application of the theory in explaining the observed bifurcations in two power electronic circuits.

The fabrication of highly durable, flexible, all‐solid‐state supercapacitors (ASCs) remains challenging because of the unavoidable mechanical stress that such devices are subjected to in wearable applications. Natural/artificial fiber textiles are regarded as prospective materials for flexible ASCs due to their outstanding physicochemical properties. Here, a high‐performance ASC is designed by employing graphene‐encapsulated polyester fiber loaded with polyaniline as the flexible electrodes and bacterial cellulose (BC) nanofiber‐reinforced polyacrylamide as the hydrogel electrolyte. The ASC combines the textile electrode capable of arbitrary deformation with the BC‐reinforced hydrogel with high ionic conductivity (125 mS cm−1), high tensile strength (330 kPa), and superelasticity (stretchability up to ≈1300%), giving rise to a device with high stability/compatibility between the electrodes and electrolyte that is compliant with flexible electronics. As a result, this ASC delivers high areal capacitance of 564 mF cm−2, excellent rate capability, good energy/power densities, and more importantly, superior mechanical properties without significant capacitance degradation after repeated bending, confirming the functionality of the ASC under mechanical deformation. This work demonstrates an effective design for a sufficiently tough energy storage device, which shows great potential in truly wearable applications.

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Oxygen-deficient bismuth oxide (r-Bi 2 O 3 )/graphene (GN) is designed, fabricated, and demonstrated via a facile solvothermal and subsequent solution reduction method. The ultrafine network bacterial cellulose (BC) as substrate for r-Bi 2 O 3 /GN exhibits high flexibility, remarkable tensile strength (55.1 MPa), and large mass loading of 9.8 mg cm −2 . The flexible r-Bi 2 O 3 /GN/ BC anode delivers appreciable areal capacitance (6675 mF cm −2 at 1 mA cm −2 ) coupled with good rate capability (3750 mF cm −2 at 50 mA cm −2 ). In addition, oxygen vacancies have great influence on the capacitive performance of Bi 2 O 3 , delivering significantly improved capacitive values than the untreated Bi 2 O 3 flexible electrode, and ultrahigh gravimetric capacitance of 1137 F g −1 (based on the mass of r-Bi 2 O 3 ) can be obtained, achieving 83% of the theoretical value (1370 F g −1 ). Flexible asymmetric supercapacitor is fabricated with r-Bi 2 O 3 /GN/BC and Co 3 O 4 /GN/BC paper as the negative and positive electrodes, respectively. The operation voltage is expanded to 1.6 V, revealing a maximum areal energy density of 0.449 mWh cm −2 (7.74 mWh cm −3 ) and an areal power density of 40 mW cm −2 (690 mW cm −3 ). Therefore, this flexible anode with excellent electrochemical performance and high mechanical properties shows great potential in the field of flexible energy storage devices.

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The challenges of solid‐state supercapacitors (SCs) for flexible and wearable electronics still remain in well balancing the electrochemical performance, mechanical stability, and processing technologies. Herein, a high‐performance, tailorable and foldable solid‐state asymmetric supercapacitor is developed via one‐step scalable chemical oxidization and MXene ink painting of N‐doped carbon fiber textile (NCFT) substrate. The employed O/N‐functionalized NCFT (ONCFT) and MXene materials under opposite potentials both incorporate excellent electrochemical behaviors of carbon‐like materials and pseudocapacitive materials, namely high rate capability and pseudocapacitance. By regulating oxidization time and MXene loading, the active layer of MXene decorated NCFT (MNCFT) and ONCFT electrodes analogously present tight skin structure, fundamentally avoiding the risk of active materials detaching from the support during mechanical deformation. As a result, the assembled MNCFT//ONCFT device not only achieves an extended voltage window of 1.6 V, high areal energy density of 277.3 μWh cm−2 and 90% capacitance retention after 30 000 cycles, but also experiences repeated folding tests. Additionally, the design makes it possible to tailor the textile‐based energy storage device (TEESD) into a designed size or shape without impairing its performance for device integration or shape conformable integration. Owing to the whole component fabrication being simple and scalable, the TEESD shows potential practical application.