Electrospinning is one of the most accessed nanofabrication techniques during the last three decades, attributed to its viability for the mass production of continuous nanofibers with superior properties from a variety of polymers and polymeric composites. Large investments from various sectors have pushed the development of electrospinning industrial setups capable of producing nanofibers in millions of kilograms per year for several practical applications. Herein, the lessons learned over three decades of research, innovations, and designs on electrospinning products are discussed in detail. The historical developments, engineering, and future opportunities of electrospun nanofibers (ESNFs) are critically addressed. The laboratory-to-industry transition gaps for electrospinning technology and ESNFs products, the potential of electrospun nanostructured materials for various applications, and academia-industry comparison are comprehensively analyzed. The current challenges and future trends regarding the use of this technology to fabricate promising nano/macro-products are critically demonstrated. We show that future research on electrospinning should focus on theoretical and technological developments to achieve better maneuverability during large-scale fiber formation, redesigning the electrospinning process around decarbonizing the materials processing to align with the sustainability agenda and the integration of electrospinning technology with the tools of intelligent manufacturing and IR 4.0.

Ternary nanocomposites synergistically combine the material characteristics of three materials, altering the desired charge storage properties such as electrical conductivity, redox states, and surface area. Therefore, to improve the energy synergistic of SnO₂, TiO₂, and three-dimensional graphene, herein, we report a facile hydrothermal technique to synthesize a ternary nanocomposite of three-dimensional graphene-tin oxide-titanium dioxide (3DG-SnO₂-TiO₂). The synthesized ternary nanocomposite was characterized using material characterization techniques such as XRD, Raman spectroscopy, FTIR spectroscopy, FESEM, and EDXS. The surface area and porosity of the material were studied using Brunauer-Emmett-Teller (BET) studies. XRD studies showed the crystalline nature of the characteristic peaks of the individual materials, and FESEM studies revealed the deposition of SnO₂-TiO₂ on 3DG. The BET results show that incorporating 3DG into the SnO₂-TiO₂ binary nanocomposite increased its surface area compared to the binary composite. A three-electrode system compared the electrochemical performances of both the binary and ternary composites as a battery-type supercapacitor electrode in different molar KOH (1, 3, and 6 M) electrolytes. It was determined that the ternary nanocomposite electrode in 6 M KOH delivered a maximum specific capacitance of 232.7 C g^-1 at 1 A g^-1. An asymmetric supercapacitor (ASC) was fabricated based on 3DG-SnO₂-TiO₂ as a positive electrode and commercial activated carbon as a negative electrode (3DG-SnO₂-TiO₂//AC). The ASC delivered a maximum energy density of 28.6 Wh kg^-1 at a power density of 367.7 W kg^-1. Furthermore, the device delivered a superior cycling stability of ∼97% after 5000 cycles, showing its prospects as a commercial ASC electrode.

Energy storage systems with non-metallic charge carriers such as ammonium-ion (NH₄ ⁺) are inherently safe and enable large-scale storage. Unlike metal ions with spherical symmetry, the intercalation of ammonium ions with a tetrahedral structure is symmetry-specific, leading to high power density and long-term cycling stability. However, developing suitable electrode materials that can reversibly host NH₄ ⁺ ions to improve electrochemical performance is challenging. To address these issues, here we synthesized a sandwich-structured ammonium vanadate (NH₄V₄O₁₀) and MXene (Ti₃C₂T_x) composite for the first time and employed it as a high-performance electrode for ammonium ion storage. Benefiting from the unique nano-architecture, the developed NH₄V₄O₁₀/MXene electrode delivered an areal capacitance of 229 mF cm⁻² at a specific current of 1 mA cm⁻² with ∼98% retention after 5000 charge–discharge cycles. Electrochemical analyses, supplemented with Raman spectroscopy and X-ray diffractometry, reveal the superior charge kinetics and structural stability of the NH₄V₄O₁₀/MXene electrode under harsh operation conditions. The cell-type ammonium ion asymmetric capacitor (AIC) assembled using NH₄V₄O₈/MXene as the positive electrode and MXene as the negative electrode delivered an energy density of 17.3 W h kg⁻¹ with excellent capacitance retention after 10 000 charge–discharge cycles. These results provide new insights for the development of safe and reliable next-generation clean energy technologies based on unconventional, non-metal-ion-based charge storage mechanisms.

A circular economy targets zero waste converting both natural and synthetic wastes to valuable products, thereby promoting sustainable development. The porous nanocarbon synthesized from bio-waste is one such product used in applications such as energy storage, catalysis, and sensors. Different techniques are employed for synthesizing carbon from the biowastes and each route results in different properties toward end-user applications. Among them, surface area and porosity are the two critical factors that influence the energy storage capabilities of these synthesized carbon nanostructures. Besides the high surface area of the bio-derived carbons, the hindrance in supercapacitive performance is owing to its low porosity. Fewer review/research papers report the porosity tuning of these carbons for their influence on enhancing the performance of energy storage devices (supercapacitors). This critical review analyses the importance of porosity in these bio-derived carbons and reviews the recent development in its synthesis techniques along with its improvement in the energy storage capability. Special attention is also delivered to identify the ambient source of biowaste for carbon electrodes (fabrication) in supercapacitors. The recent research progress in tuning the porosity of these bio-derived carbons and the influence of electrolyte with porosity in affecting its supercapacitive energy storage is elucidated here. The research challenges, future research recommendations, and opportunities in the synthesis of bio-derived porous carbon for supercapacitor applications are briefed. Graphical Abstract