Flexible supercapacitors (FSCs) are limited in flexible electronics applications due to their low energy density. Therefore, developing electrode materials with high energy density, high electrochemical activity, and remarkable flexibility is challenging. Herein, we designed nitrogen-doped porous MXene (N-MXene), using melamine-formaldehyde (MF) microspheres as a template and nitrogen source. We combined it with an electrospinning process to produce a highly flexible nitrogen-doped porous MXene nanofiber (N-MXene-F) as a self-supporting electrode material and assembled it into a symmetrical supercapacitor (SSC). On the one hand, the interconnected mesh structure allows the electrolyte to penetrate the porous network to fully infiltrate the material surface, shortening the ion transport channels; on the other hand, the uniform nitrogen doping enhances the pseudocapacitive performance. As a result, the as-assembled SSC exhibited excellent electrochemical performance and excellent long-term durability, achieving an energy density of 12.78 Wh kg⁻¹ at a power density of 1080 W kg⁻¹, with long-term cycling stability up to 5000 cycles. This work demonstrates the impact of structural design and atomic doping on the electrochemical performance of MXene and opens up an exciting possibility for the fabrication of highly FSCs.

Bismuth trioxide (BT) is considered a fascinating anode material for hybrid supercapacitors (HSCs) due to its high theoretical capacity, but the low conductivity limits further applications. With this in mind, Ce‐doped Bi₂O₃ (Ce‐BT) nanoflower spheres were synthesized by a facile and rapid microwave‐assisted solvothermal method for HSCs anode materials. It is found that the morphology of BT could be controlled by Ce doping from stacked nanosheets to well‐dispersed nanoflowers spheres and producing abundant amorphous regions, thus expediting the ion transport rate. Consequently, when the added Bi to Ce molar ratio is 40:1 (Ce‐BT‐40), it exhibited a specific capacity of 220 mAh g⁻¹ at 0.5 A g⁻¹. Additionally, when fabricating HSCs with as‐prepared Ce‐BT‐40 and CeNiCo‐LDH, an energy density of 59.1 Wh kg⁻¹ is provided at a power density of 652 W kg⁻¹. This work not only reveals the mechanism of the effect of Ce doping on the electrochemical properties of BTs, but also proposes a rapid synthesis method of Ce‐BTs by microwave‐assisted solvent method, which provides new insights for building advanced HSCs with high energy density and low cost.

The advantages of low cost, high theoretical capacity, and dependable safety of aqueous zinc ion hybrid supercapacitors (ZHSCs) enable their promising use in flexible and wearable energy storage devices. However, achieving extended cycling stability in ZHSCs is still challenged by the limited availability of carbon cathode materials that can effectively pair with zinc anode materials. Here, we report a method for synthesising heteroatom-doped carbon nanofibers using electrostatic spinning and metal-organic frameworks (specifically ZIF-8). Assembled Zn//ZPCNF-1.5 ZHSCs exhibited 193 mA h g⁻¹ specific capacity at 1 A g⁻¹ and 162.6 Wh kg⁻¹ energy density at 841.2 kW kg⁻¹. Additionally, the device showed an ultra-long cycle life, maintaining 98% capacity after 20,000 cycles. Experimental analysis revealed an increase in the number of pores and active sites after adding ZIF-8 to the precursor. Furthermore, N doping effectively enhanced Zn²⁺ ions chemical adsorption and improved Zn-ion storage performance. This work provides a feasible design strategy to enhance ZHSC energy storage capability for practical applications.

Nanocellulose has emerged as a highly promising and sustainable nanomaterial due to its unique structures, exceptional properties, and abundance in nature. In this comprehensive review, we delve into current research activities focused on harnessing the potential of nanocellulose for advanced electrochemical energy storage applications. We commence with a brief introduction to the structural features of cellulose nanofibers found within the cellulose resources’ cell walls. Subsequently, we explore various processes that have been investigated for utilizing cellulose in the realm of energy storage. In contrast to traditional binders, we place significant emphasis on the utilization of solid electrolytes and 3D printing techniques. Additionally, we examine different application areas, including supercapacitors, lithium-ion batteries, and Zn-ion batteries. Within this section, our primary focus lies in integrating nanocellulose with other active materials to develop flexible substrates such as films and aerogels. Lastly, we present our perspectives on several key areas that require further exploration in this dynamic research field in the future.