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Sodium‐ion capacitors (SICs), designed to attain high energy density, rapid energy delivery, and long lifespan, have attracted much attention because of their comparable performance to lithium‐ion capacitors (LICs), alongside abundant sodium resources. Conventional SIC design is based on battery‐like anodes and capacitive cathodes, in which the battery‐like anode materials involve various reactions, such as insertion, alloying, and conversion reactions, and the capacitive cathode materials usually depend on activated carbon (AC). However, researchers have attempted to construct SICs based on battery‐like cathodes and capacitive anodes or a combination of both in recent years. In this Minireview, charge storage mechanisms and material design strategies for SICs are summarized, with a focus on the battery‐like anode materials from both inorganic and organic sources. Additionally, the challenges in the fabrication of SICs and future research directions are discussed. [ABSTRACT FROM AUTHOR]

Laser induced graphene (LIG) based micro-supercapacitors (LIG-MSCs) have sprung up rapidly in recent years, driven by the huge demand for flexible energy storage devices. However, the low energy density arising from the limited specific surface area and few active sites of LIG-MSCs greatly limits their practical application. In this context, this work proposes an asymmetric construction of Zn@FLIG//FLIG electrodes using fluorinated polyimide (FPI) as the substrate. A more porous structure of FLIG can be achieved by the decomposition of fluorine-containing groups into gaseous products during the laser irradiation process. The interconnected porous structure of FILG further acts as an ideal substrate for the uniform electrodeposition of Zn nanosheets, which also enhances the energy density of the MSC. The areal capacitance of the FLIG based zinc-ion hybrid supercapacitor (FLIG-ZHMSC) was 42.32 mF·cm−2, more than 15 times of the commercial LIG based ZHMSC (CLIG-ZHMSC) (2.73 mF·cm−2). The energy density of FLIG-ZHMSC has been significantly increased to 15.1 μWh·cm−2, compared to 0.97 μWh·cm−2 for CLIG-ZHMSC. FLIG-ZHMSC was also able to retain 79.4% of its initial capacitance after 7000 cycles at a current density of 1 mA·cm−2. Meanwhile, FLIG-ZHMSC works stably at different bending conditions, holding a great application prospect for wearable and intelligent device applications. [Display omitted] • Fluorinated laser-induced graphene (FLIG) electrode was obtained. • Fluorine doping significantly increases the specific area of the electrode. • The electrical conductivity of the electrode was greatly enhanced. • FLIG based zinc-ion hybrid supercapacitor has high performance and good flexibility. [ABSTRACT FROM AUTHOR]

CuS/ZnS/sodium alginate/reduced graphene oxide nanocomposites (CZSrG) were prepared by physical crosslinking followed by one-step reduction and were justified as green binder-free hydrogel high-capacitance electrodes. The physical crosslinking was realized simply through the hydrogen-bond interaction between sodium alginate (SA) and graphene oxide (GO), avoiding the usage of traditional Ca2+ crosslinking agent. The hydrogel structure made of CZSrG possessed the most beneficial effect of avoiding large volume change and increasing cycle stability for supercapacitors. When used as electrode, the specific capacitance of CZSrG was 992 F·g−1 (10 mV·s−1) in a three-electrode system. Furthermore, the fabricated supercapacitors had a specific capacitance of 252.1 F·g−1 (5 mV·s−1), and a power density of 1800 Wh·kg−1 at the energy density of 2.05 Wh·kg−1. Thus, the CZSrG has a favorable electrochemical performance and wide application prospects in supercapacitors. Unlabelled Image • The CZSrG nanocomposites were designed by physical crosslinking and one-step reduction. • The physical crosslinking was binder-free and achieved by hydrogen-bonds. • The hydrogel structure replaced the traditional organic binder PTFE. • The CZSrG had excellent capacitance compared with other CuS electrodes. [ABSTRACT FROM AUTHOR]

Dandelion-like CuCo 2 O 4 arrays on nickel foam (CuCo 2 O 4 /NF) was successfully prepared for use as an advanced positive electrode material in hybrid supercapacitors. In this paper, CuCo 2 O 4 dandelion arrays grown on nickel foam (CuCo 2 O 4 /NF) was successfully synthesized by a simple hydrothermal route with post-heat-treatment for emolying as a high-performance positive electrode material for hybrid supercapacitors. Due to the unique tree-dimension porous (3D) microstructure and binder-free electrode architecture, the CuCo 2 O 4 /NF electrode deliveries a large specific capacitance of 2656.7 F g−1 at an areal current density of 1 mA cm−2. Moreover, it has an outstanding rate performance, as well as striking cycling stability. Additionally, a hybrid supercapacitors (HSCs) was fabricated using CuCo 2 O 4 as positive electrode and corals-like N -doping porous carbon (N -CCs) as negative electrode. The device exhibited a broad potential window of 1.55 V and a high specific capacitance of 273.9 F g−1, which result in a largest energy density of 91.4 Wh kg−1 and a maximum power density of 13.4 kW kg−1. Finally, the assembled device manifests a preeminent electrochemical stability which maintained a 92.32% capacitance retention after 5000 cycles. The practical application was visually validated by lighting a blue light-emitting diode. [ABSTRACT FROM AUTHOR]

Abstract Nitrogen-doped porous hollow carbon spheres were fabricated via hydrothermal pre-carbonization and pyrolysis carbonization using yeast cell templates. After that, the MnO 2 nanowires were deposited by the in-situ hydrothermal reaction. By controlling the reaction concentration, various MnO 2 nanostructures with different morphologies and electrochemical properties were obtained. The as-prepared sample exhibited an ultrahigh specific capacitance of 255 F g-1 at a current density 1 A g-1 in 1 M Na 2 SO 4 electrolyte. The MnO 2 /HCS-30 material was used as the positive electrode, and the HCS was used as the negative electrode to assemble the asymmetric supercapacitor. The maximum energy density operating at the 2.0 V voltage window is 41.4 Wh kg−1 at a power density of 500 W kg−1 and still maintains 23.0 Wh kg−1 at a power density of 7901 W kg−1. Moreover, it displayed excellent cycle stability, retained approximately 93.9% of the capacitance after 5000 cycles. This work innovatively combines biomass and energy, provides an environmentally benign strategy and new insights for the preparation of electrode materials. Graphical abstract An asymmetric supercapacitors based on MnO 2 @Biological cell template synthesized nitrogen-doped porous hollow carbon spherical composites exhibited high energy and power density and an excellent cycle stability. Image Highlights • N-doped porous hollow carbon spheres were synthesized based on yeast templates. • The MnO 2 nanowires were anchored by one-step hydrothermal deposition. • The prepared composite material exhibited a unique hollow structure. • As-prepared asymmetric supercapacitors exhibited excellent capacitive behavior. [ABSTRACT FROM AUTHOR]

Metal-organic framework (MOF)-derived materials have attracted considerable research interest for electrochemical energy storage and conversion due to their porosity characteristics and relatively simple synthesis routes. Spinel-type ternary transition metal oxide nanomaterials are promising electrode materials in energy-related fields in view of their high reactivity. In this work, flower-like manganese nickelate (MnNi 2 O 4) assembled with porous nanosheets building unite were successfully prepared by using a MOF-derived method. Benefiting from high specific surface area and rich active sites, the as - obtained product exhibited a remarkable electrochemical performance. When tested as an electrode material for supercapacitors, they delivered a high specific capacitance of 2848 F g−1 at 1 A g−1 and a good stability of 93.25% capacitance retention after 5000 cycles at 10 A g−1. To examine their practical application, a hybrid supercapacitor was fabricated using the as-synthesized MnNi 2 O 4 as a positive electrode and active carbon (AC) as a negative electrode. The assembled devices exhibited a high energy density of 142.8 Wh kg−1 at a high power density of 800 W kg−1. When the power density reached 16 kW kg−1, they still delivered a high energy density of 56.8 Wh kg−1. The superior electrochemical performance can be ascribed to the unique microstructures, elemental composition and synergism of flower-like MnNi 2 O 4. Porous flower-like MnNi 2 O 4 nanomaterials was prepared by metal-organic framework-derived synthesis route for high-performance supercapacitors. Image 1 • Porous MnNi 2 O 4 Microflower was successfully prepared. • Metal-organic Framework-derived synthesis route was adopted. • The as-prepared MnNi 2 O 4 delivery excellent supercapacitive performance. [ABSTRACT FROM AUTHOR]