[en] Although Lithium-ion batteries for consumer electronics have made substantial advances, supercapacitor also possess very attractive properties such as higher power density, short charging time and long cycle life over repeated cycles which makes them promising candidate for frequency regulators in grids, voltage stabilizers in power lines, military devices, hybrid electrical vehicles, and consumer electronics. Still, researchers in the field of energy storage are focused on improving the energy density of these devices, along with their power density, which will kick-start new innovations in flexible and lightweight electronics

[en] Recently, there has been great research interest in the development of composites (core–shell structures) of carbon nanotubes (CNTs) with metal oxides for improved electrochemical energy storage, photonics, electronics, catalysis, etc. Currently, the synthetic strategies for metal oxides/hydroxides are well established, but the development of core–shell structures by robust, cost-effective chemical methods is still a challenge. The main drawbacks for obtaining such electrodes are the very complex synthesis methods which ultimately result in high production costs. Alternatively, the solution based method offers the advantages of simple and cost effective synthesis, as well as being easy to scale up. Here, we report on the development of multi-walled carbon nanotube–manganese oxide (CNT–MnO_2) core–shell structures. These samples were directly utilized for asymmetric supercapacitor (ASC) applications, where the CNT–MnO_2 composite was used as the positive electrode and ZIF-8 (zeolitic imidazolate framework, ZIF) derived nanoporous carbon was used as the negative electrode. This unconventional ASC shows a high energy density of 20.44 W h kg"−"1 and high power density of 16 kW kg"−"1. The results demonstrate that these are efficient electrodes for supercapacitor application. (paper)

[en] Highlights: → Nickel cobaltite (NiCo₂O₄) nanorods and nanoflakes are synthesized by the chemical bath deposition method. → NiCo₂O₄ nanorods exhibit the largest specific capacitance of 490 F g^-1 at energy and power densities of 45 Wh kg^-1 and 2 kW kg^-1, respectively. → NiCo₂O₄ nanorods exhibit a markedly higher capacitance and energy density than NiCo₂O₄ nanoflakes. - Abstract: Nickel cobaltite (NiCo₂O₄) films containing nanorods and nanoflakes are synthesized on indium tin oxide (ITO) substrates by a chemical bath deposition method and calcination process at 300 deg. C for 3 h. The NiCo₂O₄/ITO films are used as electrodes for supercapacitor applications, and electrochemical properties of the NiCo₂O₄ nanostructures are examined by cyclic voltammetry and charge-discharge experiments. NiCo₂O₄ nanorods exhibit the largest specific capacitance, with a value of 490 F g^-1at energy and power densities of 45 Wh kg^-1 and 2 kW kg^-1, respectively. This is significantly better than the performance of NiCo₂O₄ nanoflakes. Cycle-life tests show that the specific capacitance of NiCo₂O₄ is stable even after 1000 cycles, indicating its high potential for supercapacitor applications. The low cost and environmental friendliness of NiCo₂O₄ nanorods, coupled with its high supercapacitor performance, offer advantages over other transition metal oxides used for supercapacitors.

[en] Highlights: • An economically viable strategy for the preparation of nanoporous carbon is reported. • This study shows a promising future for jute as a natural precursor for nanoporous carbon. • The obtained nanoporous carbon shows a high surface area (981 m² g⁻¹). • These carbons could be useful for a myriad of applications including water purification.