Chemically deposited Bi2S3:PbS solid solution thin film as supercapacitive electrode

The mineral manaksite, KNaMnSi4O10, as a supercapattery-type electrochemical energy storage material

The manaksite mineral KNaMnSi4O10 was synthesized and used to fabricate electrodes, which were investigated for electrochemical energy storage (EES) application using cyclic voltammetry (CV), galvanostatic charge and discharge (GCD), and electrochemical impedance spectroscopy (EIS). Optimum weight percentages (wt%) of electrode components were established as 10 wt% polytetrafluoroethylene (PTFE) binder, 15 wt% RuO2 and 5 wt% carbon black. RuO2 was added to improve electrical conductivity. A ratio of 13 : 3 for KNaMnSi4O10 : RuO2 was used in the fabrication of the electrode. A study of the suitable electrolyte and corresponding concentration to use was done using NaOH and KOH, both at concentrations of 1 M, 3 M and 6 M, with 3 M NaOH as the optimum electrolyte and concentration. The KNaMnSi4O10 yielded a specific capacity of 106 mA h g-1. An investigation into the energy storage mechanism from a plot of log I(ν) vs. log ν, where I is current and ν is the scan rate gave a b value parameter of 0.8; that is, in-between 0.5 obtained for a pure battery material and 1.0 for a pure capacitor material. Accordingly, KNaMnSi4O10 exhibited a battery-supercapacitor duality phenomenon consistent with supercapattery materials. The KNaMnSi4O10 electrochemical system involved both capacitive and diffusion-controlled processes and was found to have good cyclic stability. It is concluded that KNaMnSi4O10 is a potential electrochemical energy storage material.

Facile Fabrication of Polyaniline/Pbs Nanocomposite for High-Performance Supercapacitor Application

In this work, a polyaniline/lead sulfide (PANI/PbS) nanocomposite was prepared by combining the in situ oxidation polymerization method and the surface adsorption process. This nanocomposite was applied as a supercapacitor electrode. The crystal structure, nanomorphology, and optical analysis of PANI and PANI/PbS were investigated. The electrochemical performance of the designed PANI/PbS electrode-based supercapacitor was tested by using cyclic voltammetry (CV), chronopotentiometry (CP), and AC impedance techniques in HCl and Na2SO4 electrolytes. The average crystallite size of the PANI/PbS nanocomposite is about 43 nm. PANI/PbS possesses an agglomerated network related to PANI with additional spherical shapes from PbS nanoparticles. After the PANI/PbS nanocomposite formation, there are enhancements in their absorption intensities. At a current density of 0.4 A g-1, the specific capacitance of PANI/PbS in Na2SO4 and HCl was found to be 303 and 625 F g-1, respectively. In HCl (625 F g-1 and 1500 mF cm-2), the gravimetric and areal capacitances of the PANI/PbS electrode are nearly double those of the Na2SO4 electrolyte. Also, the average specific energy and specific power density values for the PANI/PbS electrode in HCl are 4.168 Wh kg-1 and 196.03 W kg-1, respectively. After 5000 cycles, the capacitance loses only 4.5% of its initial value. The results refer to the high stability and good performance of the designed PANI/PbS as a supercapacitor electrode.

Preparation and application of a flower-rod-like Bi2S3/Co3O4/rGO/nickel foam supercapacitor electrode

Herein, we have prepared a new nanocomposite Bi2S3/Co3O4/rGO/Ni foam substrate electrode through hydrothermal synthesis and an annealing process.

In-situsputtered 2D-MoS2nanoworms reinforced with molybdenum nitride towards enhanced Na-ion based supercapacitive electrodes

We report the fabrication of binder-free, low-cost and efficient hybrid supercapacitive electrode based on the hexagonal phase of two-dimensional MoS₂nanoworms reinforced with molybdenum nitride nanoflakes deposited on stainless steel (SS) substrate using reactive magnetron sputtering technique. The hybrid nanostructured MoS₂-Mo₂N/SS thin film working electrode delivers a high gravimetric capacitance (351.62 F g^-1at 0.25 mA cm^-2) investigated in 1 M Na₂SO₄aqueous solution. The physisorption/intercalation of sodium (Na⁺) ions in electroactive sites of MoS₂-Mo₂N composite ensures remarkable electrochemical performance. The deposited porous nanostructure with good electrical conductivity and better adhesion with the current collector demonstrates a high-energy density of 82.53 Wh kg^-1in addition to a high-power density of 24.98 kW kg^-1. Further, excellent capacitance retention of 93.62% after 4000 galvanostatic charge-discharge cycles elucidated it as a promising candidate for realizing high-performance supercapacitor applications.

High Stability and Long Cycle Life of Rechargeable Sodium-Ion Battery Using Manganese Oxide Cathode: A Combined Density Functional Theory (DFT) and Experimental Study

Sodium-ion batteries (SIBs) can develop cost-effective and safe energy storage technology for substantial energy storage demands. In this work, we have developed manganese oxide (α-MnO2) nanorods for SIB applications. The crystal structure, which is crucial for high-performance energy storage, is examined systematically for the metal oxide cathode. The intercalation of sodium into the α-MnO2 matrix was studied using the theoretical density functional theory (DFT) studies. The DFT studies predict Na ions' facile diffusion kinetics through the MnO2 lattice with an attractively low diffusion barrier (0.21 eV). When employed as a cathode material for SIBs, MnO2 showed a moderate capacity (109 mAh·g-1 at C/20 current rate) and superior life cyclability (58.6% after 800 cycles) in NaPF6/EC+DMC (5% FEC) electrolyte. It shows a much higher capacity of 181 mAh·g-1 (C/20 current rate) in NaClO4/PC (5% FEC) electrolyte, though it suffers fast capacity fading (11.5% after 800 cycles). Our findings show that high crystallinity and hierarchical nanorod morphology of the MnO2 are responsible for better cycling performance in conjunction with fast and sustained charge-discharge behaviors.

The electrochemical kinetics of cerium selenide nano-pebbles: the design of a device-grade symmetric configured wide-potential flexible solid-state supercapacitor

Next-generation portable flexible electronic appliances require liquid-free energy storage supercapacitor devices to eliminate leakage and to support mechanical bending that is compatible with roll-to-roll technologies. Hence, a state-of-the-art process is presented to design a solid-state, wide-potential and flexible supercapacitor through the use of nano-pebbles of cerium selenide via a simple successive ionic layer adsorption and reaction (SILAR) method that could allow an industry scalable route. We strongly believe that this is the first approach amongst physical and chemical routes not only for synthesizing cerium selenide in thin-film form but also using it for device-grade supercapacitor applications. The designed solid-state symmetric supercapacitor assembled from cerium selenide electrodes sandwiched by PVA-LiClO₄ gel electrolyte attains a wide potential window of 1.8 V with capacitance of 48.8 F g^-1 at 2 mV s^-1 and reveals excellent power density of 4.89 kW kg^-1 at an energy density of 11.63 W h kg^-1. The formed device is capable of 87% capacitive retention even at a mechanical bending angle of 175°. Lighting up a strip of 21 parallel connected red LEDs clearly demonstrates the practical use of the designed symmetric solid-state supercapacitor, aiming towards the commercialization of the product in the future.

Novel chemical route for CeO2/MWCNTs composite towards highly bendable solid-state supercapacitor device

Electrode materials having high capacitance with outstanding stability are the critical issues for the development of flexible supercapacitors (SCs), which have recently received increasing attention. To meet these demands, coating of CeO₂ nanoparticles have been performed onto MWCNTs by using facile chemical bath deposition (CBD) method. The formed CeO₂/MWCNTs nanocomposite exhibits excellent electrochemical specific capacitance of 1215.7 F/g with 92.3% remarkable cyclic stability at 10000 cycles. Light-weight flexible symmetric solid-state supercapacitor (FSSC) device have been engineered by sandwiching PVA-LiClO₄ gel between two CeO₂/MWCNTs electrodes which exhibit an excellent supercapacitive performance owing to the integration of pseudocapacitive CeO₂ nanoparticles onto electrochemical double layer capacitance (EDLC) behaved MWCNTs complex web-like structure. Remarkable specific capacitance of 486.5 F/g with much higher energy density of 85.7 Wh/kg shows the inherent potential of the fabricated device. Moreover, the low internal resistance adds exceptional stability along with unperturbed behavior even under high mechanical stress which can explore its applicability towards high-performance flexible supercapacitor for advanced portable electronic devices.

Bi2S3 nanorod-stacked hollow microtubes self-assembled from bismuth-based metal-organic frameworks as advanced negative electrodes for hybrid supercapacitors

Bismuth sulfide (Bi2S3) with a lamellar structure has emerged as a promising negative electrode material for supercapacitors (SCs) due to its high theoretical specific capacity. Meanwhile, the improvement of electrochemical properties strongly depends on the size, shape and morphologies of Bi2S3 nanomaterials. Herein, the hierarchical Bi2S3 nanorod-stacked hollow microtubes are self-assembled through a facile self-sacrificing template strategy from bismuth-based metal-organic framework microprisms. Benefiting from the unique structures with a large specific surface area (54.3 m2 g-1), the as-prepared Bi2S3 exhibits an ultrahigh specific capacity (532 C g-1 at 1 A g-1) as a negative electrode for SCs, outperforming other reported Bi2S3 materials.

Sulfur-Deficient Bismuth Sulfide/Nitrogen-Doped Carbon Nanofibers as Advanced Free-Standing Electrode for Asymmetric Supercapacitors

The use of free-standing carbon-based hybrids plays a crucial role to help fulfil ever-increasing energy storage demands, but is greatly hindered by the limited number of active sites for fast charge adsorption/desorption processes. Herein, an efficient strategy is demonstrated for making defect-rich bismuth sulfides in combination with surface nitrogen-doped carbon nanofibers (dr-Bi₂ S₃ /S-NCNF) as flexible free-standing electrodes for asymmetric supercapacitors. The dr-Bi₂ S₃ /S-NCNF composite exhibits superior electrochemical performances with an enhanced specific capacitance of 466 F g^-1 at a discharge current density of 1 A g^-1 . The high performance of dr-Bi₂ S₃ /S-NCNF electrodes originates from its hierarchical structure of nitrogen-doped carbon nanofibers with well-anchored defect-rich bismuth sulfides nanostructures. As modeled by density functional theory calculation, the dr-Bi₂ S₃ /S-NCNF electrodes exhibit a reduced OH^- adsorption energy of -3.15 eV, compared with that (-3.06 eV) of defect-free bismuth sulfides/surface nitrogen-doped carbon nanofiber (df-Bi₂ S₃ /S-NCNF). An asymmetric supercapacitor is further fabricated by utilizing dr-Bi₂ S₃ /S-NCNF hybrid as the negative electrode and S-NCNF as the positive electrode. This composite exhibits a high energy density of 22.2 Wh kg^-1 at a power density of 677.3 W kg^-1 . This work demonstrates a feasible strategy to construct advanced metal sulfide-based free-standing electrodes by incorporating defect-rich structures using surface engineering principles.

Hexagonal VS2 Anchored MWCNTs: First Approach to Design Flexible Solid-State Symmetric Supercapacitor Device

Transition metal chalcogenides (TMCs) embedded with a carbon network are gaining much attention because of their high power capability, which can be easily integrated to portable electronic devices. Facile chemical route has been explored to synthesize hexagonal structured VS₂ nanoparticles onto multiwalled carbon nanotubes (MWCNTs) matrix. Such surface-modified VS₂/MWCNTs electrode has boosted the electrochemical performance to reach high capacitance to 830 F/g and excellent stability to 95.9% over 10 000 cycles. Designed flexible solid-state symmetric supercapacitor device (FSSD) with a wide voltage window of 1.6 V exhibited maximum gain in specific capacitance value of 182 F/g at scan rate of 2 mV/s along with specific energy of 42 Wh/kg and a superb stability of 93.2% over 5000 cycles. As a practical approach, FSSD has lightened up "VNIT" panel consisting of 21 red LEDs.

Highly conductive energy efficient electroless anchored silver nanoparticles on MWCNTs as a supercapacitive electrode

Electroless-deposited Ag nanoparticles over MWCNTs towards energy efficient supercapacitive electrodes.