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The synthesis of Laser-Induced Graphene (LIG) through the laser ablation process of carbon-containing materials is a rapid and scalable process which enables the production of graphene in a cost-effective manner. In recent years, metal oxide – graphene composite electrodes have gained a lot of importance due to their use in various Energy Storage Devices (ESDs). In our investigation, we manufacture composite electrodes of manganese dioxide (MnO 2) and LIG through a hydrothermal process and use it as electrodes in Flexible Supercapacitors. This method deviates from traditional procedures as it eliminates the requirement for binders in creating composite electrodes, given that MnO 2 can be directly deposited onto the LIG electrodes. The assembled all-Flexible Supercapacitor (FSC), featuring unique LIG-MnO 2 composite electrodes, showcased a remarkable areal capacitance of 66.5 mF cm−2 at 5 mV s−1 scan rate. The device also exhibited a very high areal energy density (2.3 mWh cm−2) and power density (19.7 mW cm−2) at 0.2 mA cm−2 current density. Also, 82 % capacitance retention was observed at the end of 2000 cycles and the device also exhibited a good flexibility during bending tests, as evidenced by an 80 % capacitance retention after 100 bending cycles. [ABSTRACT FROM AUTHOR]

• MnO 2 /CNF/Ag nanofabric electrodes are developed for flexible supercapacitors. • The brittle issue in the CNF electrode is greatly improved by an Ag incorporation. • The optimized MnO 2 /CNF/Ag electrode has a specific capacitance of 184 F/g at 1 A/g. • An energy density of 16.3 Wh/kg and a power density of 400 W/kg was achieved. • A capacitance retention rate of 87 % was demonstrated when subjected to bending. Flexible supercapacitors are gaining increasing popularity due to their potential in powering portable, wearable, and lightweight electronic devices. In this study, we have successfully developed a high-performance flexible electrode for quasi-solid-state supercapacitors by incorporating Ag into carbon nanofibers (CNF) through electrospinning, and growing MnO 2 as an active material on the electrode using an in-situ redox method. The Ag and MnO 2 co-decorated CNF electrode offers several advantages over conventional CNF electrodes, including an enlarged reaction area, higher charge storage capacity, and improved resistance to brittleness issues. Among all the quasi-solid-state supercapacitors tested, the MnO 2 -decorated electrode with an optimized Ag incorporation exhibited the highest specific capacitance of 184 F/g at a current density of 1 A/g, representing a remarkable 17-fold increase compared to the reference CNF electrode. Furthermore, the Ag and MnO 2 co-decorated electrode demonstrated an energy density of 16.3 Wh/kg and a power density of 400 W/kg at the same current density. Notably, the electrode exhibited excellent flexibility, with a capacitance retention rate of 87 % when subjected to bending with a curvature ranging from 5 to 1.25 cm. Our results suggest that the Ag and MnO 2 co-decorated CNF electrode holds great promise for flexible energy storage applications. [Display omitted] [ABSTRACT FROM AUTHOR]

ZIF derived selenides have become a promising battery-type electrode material, but pure ZIF derived materials tend to agglomerate, averting active sites from full exposure. Herein, a hierarchical Co doped Ni 3 Se 4 on carbon nanofibers modified by ZIF-67 was fabricated by co-electrospinning, calcination and solvothermal synthesis, whose mass ratio of ZIF-67 to PAN and the type of chalcogenides were regulated. Among them, CNF-Co(1:1)@NiSe, with the feature of battery-type materials, displayed the large specific capacitance of 749.27 F g−1 at 0.5 A g−1 and superb rate performance when the current density increased from 0.5 to 10 A g−1, owing to its unique hierarchical structure along with synergistic effect of Co-doped Ni 3 Se 4 , Co-N-C, and CNF. Notably, a solid-state hybrid supercapacitor (CNF-Co(1:1)@NiSe//active carbon) was build, and delivered the maximum energy density of 32.36 Wh kg−1 at 1 A g−1 along with the maximum power density of 7999.99 W kg−1 at 10 A g−1. In addition, the supercapacitor exhibited excellent cycle stability during 5000 cycles and was successfully used for the luminescence of LED, revealing a good application prospect for CNF-Co(1:1)@NiSe. [ABSTRACT FROM AUTHOR]

The binder-free supercapacitors were fabricated from polyaniline (PANI)@MnO 2 @flexible carbon nanofibers (CNFs) composite flexible electrodes. The flexible electrodes were constructed using a layer-by-layer synthetic strategy: a large-area MnO 2 ultrathin nanosheets firstly grew onto the surface of CNFs by self-decomposition of KMnO 4 , and then the PANI was in-situ coated on MnO 2 ultrathin nanosheets in turn through a dilute-solution polymerization to form PANI@MnO 2 @CNFs ternary electrode. In PANI@MnO 2 @CNFs electrode, the two-dimensional sheet-like structure provided by the PANI@MnO 2 nanosheets could be served as a high specific surface area and electrically conductive network for fast transport of electrolyte ions and electrons in the reaction, where PANI and MnO 2 were high-performance supercapacitor electrode materials. The specific capacitance of single PANI@MnO 2 @CNFs electrode was 654 F/g at the scan rate of 10 mV/s in Na 2 SO 4 electrolyte, and the capacitance retention was about 88.8% after 1000 cycles. Furthermore, the as-prepared symmetric supercapacitor with a PVA/Na 2 SO 4 gel electrolyte exhibited the maximum energy density of 27.9 Wh/kg at the power density of 400 W/kg, which was superior or similar to previously reported values of PANI-based supercapacitor. The as-prepared supercapacitors exhibited good electrochemical performance and high flexibility, which was a meaningful exploration for the application of flexible electrodes in the production of multi-element electrode materials for supercapacitors. The binder-free supercapacitors were fabricated from polyaniline(PANI)@MnO 2 nanosheets@flexible carbon nanofibers (CNFs) composite electrodes. The specific capacitance of single PANI@MnO 2 @CNFs electrode was about 654 F/g at scan rate of 10 mV/s in Na 2 SO 4 electrolyte, and the capacitance retention was about 88.8% after 1000 cycles. Furthermore, the as-prepared symmetric supercapacitor with a PVA/Na 2 SO 4 gel electrolyte exhibited the maximum energy density of 27.9 Wh/kg at the power density of 400 W/kg. [Display omitted] [ABSTRACT FROM AUTHOR]

• Hierarchical porous carbon (HPC) is obtained with three-dimensional (3D) structure. • The HPC with highly fluffy 3D continuous network is found as an ideal support. • HPC-supported MnO 2 nanofibers composite is achieved as a supercapacitor material. • The as-prepared MnO 2 @HPC composite has 3D interpenetrating network structure. • The MnO 2 @HPC composite presents excellent electrochemical performance. For improving the conductivity of porous carbon and the utilizations of its pore structures, a hierarchical porous carbon (HPC) had been developed with highly fluffy three-dimensional (3D) continuous network structure. Using the HPC as a support, a novel MnO 2 @HPC composite with 3D interpenetrating network structure was prepared as electrode material of supercapacitor via simple hydrothermal method. When the hydrothermal reaction temperature was 100°C, the MnO 2 nanofibers (∼5 nm) were uniformly grown on and within the fluffy 3D porous network of the HPC, forming a composite with interpenetrating network structure. The as-prepared composite (MnO 2 @HPC-100) exhibited the characteristics of both electric double-layer capacitance and pseudo-capacitance, which had a high specific capacity of 368 F g−1 at a current density of 0.5 A g−1 and 186 F g−1 at 10 A g−1 (50.5% retention). In addition, the asymmetric supercapacitor device was assembled with a relatively high energy density of 88.2 Wh Kg−1 at a power density of 162 W Kg−1. The device had a high capacity retention rate of 95% after 10000 cycles, and the coulomb efficiency was stable at 99.7%, showing the excellent stability of the composite. Therefore, the MnO 2 @HPC-100 composite has great application prospects in energy storage. [Display omitted] [ABSTRACT FROM AUTHOR]

Carbon-based materials have emerged as promising anode candidates for lithium-ion capacitors (LICs) owing to the advantages of high electronic conductivity and environmental benignity. However, further development of carbonaceous anodes has been greatly hindered by the sluggish kinetics and insufficient cycling stability. Herein, mesopore-rich N-doped carbon nanofibers (MNCNF) membranes are designed as a free-standing anode material to achieve ultra-high rate and ultra-long lifespan Li storage performance. The interconnected network with rich mesopore volume, high doping level of pyridinic/pyrrolic N, and expanded interlayer spacing affords the as-fabricated MNCNF anode abundant active sites, promoted electronic conductivity and superior diffusion kinetics. With prominent merits of pore and defect engineering, MNCNF anode manifests extraordinary Li storage performance in terms of ultra-high rate capability (139 mA h g−1 at 50 A g−1) and ultra-long cycling stability (370 mA h g−1 after 10000 cycles at 10 A g−1). More importantly, LICs by using MNCNF as anodes deliver a high energy density of 165 Wh kg−1 and an ultra-high power density of 132 kW kg−1, together with a high capacitance retention of 84% after 20000 cycles. This study demonstrates the combination of pore and defect engineering for boosting Li storage performance and holds great promise for practical applications. [Display omitted] [ABSTRACT FROM AUTHOR]

• Sandwich-structured C/Mn/C with a triple layer were fabricated by electrospinning. • Well-preserved MnO 2 NPs in the interlayer are utilized as electroactive sites. • Hollow core present in the interlayer serves as an excellent conductive network. • Symmetric C/Mn(10)/C electrode showed high specific capacitance and long cycle life. • Asymmetric C/Mn(10)/C offers high energy density in a high potential window. Sandwich-structured carbon nanofiber/MnO 2 /carbon nanofiber composites with a triple layer are fabricated by electrospinning. The optimized sandwich-structured composite electrodes exhibit the maximum specific capacitance of 220 F/g at 1 mA/cm2, a high energy density of 24.63 Wh/kg at a power density of 400 W/kg, and an excellent retention rate of 94% after 10,000 cycles. The stable spatial distribution of MnO 2 nanoparticles between the upper and lower carbon nanofiber webs allowed full use of the well-preserved MnO 2 nanoparticles in the interlayer as electroactive sites, providing better electrochemical performance. Furthermore, the hollow core present in the interlayer serves as an excellent conducting network, providing a short ion diffusion path for both ions and electrons. In addition, the asymmetric supercapacitor shows excellent cycling behavior between 0 and 1.4 V and a large energy density of 44.3 Wh/kg at a power density of 400 W/kg, showing great potential in the development of energy storage devices with high energy density for practical applications. [ABSTRACT FROM AUTHOR]

The development of high-energy lithium-ion and sodium-ion capacitors (LICs and SICs) is still a challenge due to the kinetics mismatch between the insertion/deinsertion anode and adsorption/desorption cathode. Here, high-level N/P-doped Sn-carbon nanofibers (Sn-NP-CNFs) were fabricated via an electrospinning technique followed by pre-oxidization and carbonization. The N/P-doping increased the defects and carbon interlayer distance to inhibit the precipitation and volume expansion of the Sn and improve the Li/Na-adsorption, resulting in an ultrahigh pseudocapacitance and rate capability of the Sn-NP-CNF. An advanced LIC and SIC were composed of an activated carbon cathode and a Sn-NP-CNF anode. The LIC and SIC displayed ultrahigh energy densities (186.0 Wh kg−1 and 134.6 Wh kg−1) and power densities (20.0 kW kg−1 achieved at 22.2 Wh kg−1) with superior energy retentions (83.7% and 79.8% after 10,000 cycles at 5.0 A g−1). [ABSTRACT FROM AUTHOR]

The lignin-based multi-channels carbon nanofibers (MCNFs) @ SnO 2 nanocomposites with various microstructures are synthesized via co-electrospinning by regarding Poly (vinyl pyrrolidone) (PVP)–SnCl 2 ·2H 2 O as shell materials and lignin-Poly (methyl methacrylate) (PMMA) at different mass ratios as core materials, followed by heat treatment and acid treatment. The experimental results show that when the mass ration of lignin to PMMA in the core region is 5:5, the obtained nanocomposites possess hierarchical internal channels, porous surface, and high specific surface area. This optimized nanocomposite as supercapacitor electrode shows high specific capacitance of 406 F g−1 at current density of 0.5 A g−1. In addition, the electrode exhibits unexceptionable cycling stability with only 5% capacitance decay over 10 000 cycles at 10 A g−1. Furthermore, the symmetric supercapacitor using the optimized nanocomposites as electrodes possesses remarkable power and energy densities. The superior electrochemical performance of nanocomposites is benefited from the hierarchical structures of MCNFs, faradaic pseudocapacitance of SnO 2 , and pore-forming effect of SnCl 2 ·2H 2 O. The unique hierarchical nanocomposites show great potential in future development of lignin-based low-cost, non-toxic and eco-friendly carbon materials for high-performance energy storage devices. [ABSTRACT FROM AUTHOR]

Conducting polymer nanoarray structures had attracted increasing attention as potential electrode materials in supercapacitor devices. In this article, the orderly and highly dense polyaniline (i.e., PANI) nanorod arrays had been successfully grown onto the surface of carbon nanofibers(i.e., CNFs) to form PANI@CNFs composite via a one step of facile chemical oxidation method. The specific capacity of the single PANI@CNFs composite electrode was 758 C/g and 720 C/g at current densities of 1.0 and 5.0 A/g, respectively, while the cycling stability could maintain 85% of the initial capacity after 1000 charge-discharge cycles. Furthermore, two pieces of PANI@CNFs composite electrodes were fabricated into a symmetric all-solid-state flexible supercapacitor device to drive small electronic equipments using polyvinyl alcohol-H 2 SO 4 hydrogel as solid electrolyte, while the normal filter paper acted as a separator. The as-prepared symmetric supercapacitor device had excellent electrochemical performance with specific capacitance of 285 F/g at a current density of 0.5 A/g. The maximum energy density was 10.04 Wh/kg at a power density of 225 W/kg and showed no obvious decrease in the performance with a bending angle of 45° or 90°. The as-prepared symmetric all-solid-state flexible supercapacitor device had good promising applications in small wearable electronics. The orderly and highly dense polyaniline nanorod arrays had been successfully grown onto the surface of carbon nanofibers via a one step of facile chemical oxidation method. The as-prepared symmetric supercapacitor device had excellent electrochemical performance with specific capacitance of 285 F/g at a current density of 0.5 A/g, and the maximum energy density was 10.04 Wh/kg at a power density of 225 W/kg. The as-prepared symmetric all-solid-state flexible supercapacitor device had good promising applications in small wearable electronics. Image 1 • Orderly and highly dense PANI nanorod arrays fenced onto the surface of CNFs was designed. • The specific capacity of 758 C/g was obtained when PANI@CNFs acted as the electrode. • The maximum energy density of PANI@ CNFs was 10.04 Wh/kg at a power density of 225 W/kg. • The small wearable electronics could be drove by the as-prepared all-solid-state flexible supercapacitor device. [ABSTRACT FROM AUTHOR]

Carbon nanofibers (CNFs) were directly synthesized on the surface of 304 stainless steel (SS) mesh by a facile one-step ethanol flame synthesis method under a controllable temperature of ∼850 °C, as well as the γ-Fe 2 O 3 particles. The resulted CNFs/Fe 2 O 3 /SS mesh electrode is used to assemble a symmetric supercapacitor (SC) with redox active acidic electrolyte, and it exhibits a large area specific capacitance (C a) up to 2412.6 mF cm−2 at a current density of 3 mA cm−2, and a high energy density of 14.57 mW h cm−3 at a power density of 65.22 mW cm−3. The electrodes also show high cyclic stability, and the specific capacitance retention remains to be 93.55% after 1000 charge-discharge cycles. An asymmetric SC is assembled using the CNFs/Fe 2 O 3 /SS as cathode and the WO 3 /Ti mesh as anode, respectively. It also possesses a high energy density of 9.08 mW h cm−3 at a power density of 70.33 mW cm−3 in a potential window of 0–1.5 V. Their high capacitive performance and good cyclic stability in the acidic electrolyte containing Fe2+/Fe3+ additive could be due to the intrinsic functionalized CNFs produced by the flame deposit method and the reaction balance of the ferric species between the electrode and the electrolyte during the electrochemical process. The facile fabrication method and superior performance of the CNFs/Fe 2 O 3 /SS mesh make it promising electrodes for high-performance SCs with specific electrolyte. [ABSTRACT FROM AUTHOR]