Design and Regulation of Novel MnFe2O4@C Nanowires as High Performance Electrode for Supercapacitor

Fabrication of composite GO/NiFe2O4-MnFe2O4-CoFe2O4 anode material: Toward high performance hybrid supercapacitors

Here, NiFe2O4, MnFe2O4, and CoFe2O4 nanoferrites are prepared by coprecipitation synthesis technique from nickel, manganese, and cobalt chloride precursors. Synthesized nanoferrites are annealed by calcination process at 800°C for 2 h. To produce a novel anode electrode material for asymmetric supercapacitors (ASCs), the composite material of GO/NiFe2O4-MnFe2O4-CoFe2O4 is fabricated. Physicochemical aspects of the synthesized nanoferrites are evaluated. X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and x-ray photoelectron spectroscopy tests are conducted, respectively. The electrochemical activities are studied by cyclic voltammetry, glavanostatic charge-discharge, and electrochemical impedance spectroscopy (EIS) in 2 M KOH as the electrolyte. In three electrode system, the novel GO/NiFe2O4-MnFe2O4-CoFe2O4 electrode displays a high specific capacity of 325 C g-1 and preserves about 99.9% of its initial specific capacity. The GO/NiFe2O4-MnFe2O4-CoFe2O4//GO ASCs device is assembled using GO/NiFe2O4-MnFe2O4-CoFe2O4, GO, and 2 M KOH solution as the positive electrode, negative electrode, and electrolyte, respectively. Significantly, the GO/NiFe2O4-MnFe2O4-CoFe2O4//GO ASCs represent an outstanding energy density of 50.5 W h kg-1 at power density of 2560 W kg-1. Through the long-term charge discharge cycling tests, this ASC device illustrates about 93.7% capacity retention after 3000 cycles. Then, the present study provides the NiFe2O4-MnFe2O4-CoFe2O4 composite nanoferrites as a novel favorable candidate for anode material. RESEARCH HIGHLIGHTS: Simple and green synthesis of magnetic NiCo2O4/NiO/rGO composite nanostructure using natural precursor. Fabricating and designing an efficient semiconductor for degradation ability. NiCo2O4/NiO/rGO nanocomposite with advanced photo elimination catalytic routine. The photocatalytic performance of NiCo2O4/NiO/rGO was surveyed for the degradation of various antibiotics below visible radiation. Efficiency was 92.9% to eliminate tetracycline. We developed a synergetic approach to prepare a novel active material composed of GO/ NiFe2O4-MnFe2O4-CoFe2O4 by a hybrid electrode material. Green synthesis method was accomplished to attain NiCo2O4/NiO/rGO nanocomposite with advanced photo elimination catalytic routine. The oxide nanobundles were prepared with a rapid and eco-friendly method. In order to investigation of the effect of natural precursor, morphology and shape of nanoproducts was compared. NiCo2O4/NiO/rGO nanobundles possess a suitable bandgap in the visible area.

Spinel LiMn2O4 nanoparticles fabricated by the flexible soft template/Pichini method as cathode materials for aqueous lithium-ion capacitors with high energy and power density

Spinel LiMn2O4 (LMO) with a three-dimensional structure has become one of the cathode materials that has gained the most interest due to its safety, low price and abundant resources. However, the lithium ion transmission is limited by large particle size and particle agglomeration of LMO. Thus, reducing the particle size and agglomeration of LMO can effectively improve its lithium ion transmission. Here, we synthesized a LMO cathode material with a nanoscale crystal size using the flexible expanded graphite (EG) soft template and Pichini method. EG-controlled particle size and particle agglomeration of LMO is conducive to charge transfer and diffusion of lithium ions between LMO and the electrolyte, meanwhile, there are more redox sites on the nanosized LMO particles, which makes the redox reaction of LMO more thorough during the charge and discharge process, resulting in high capacitance performance. In order to obtain the considerably required lithium-ion capacitors (LICs) with high energy density and power density, we assembled aqueous LMO//activated carbon (AC) LICs with 5 M LiNO3 as the aqueous electrolytes, which are environmentally friendly, safe, low cost and have higher electrical conductivity than organic electrolytes. The optimal LIC has an energy density of 32.63 W h kg-1 at a power density of 500 W kg-1 and an energy density of 8.06 W h kg-1 at a power density of 10 000 W kg-1, which is higher than most of the LMO-based LICs in previous reports. After 2000 cycles, the specific capacitance retention rate was 75.9% at a current density of 3 A g-1. Therefore, our aqueous LMO//AC LICs synthesized by the soft template/Pichini method have wide prospects and are suitable for low-cost, high-safety and high-power applications.

Investigation on NiWO4/PANI composite as an electrode material for energy storage devices

NiWO4/PANI was synthesized by an in situ chemical oxidative polymerization route. Incorporation of NiWO4 in a PANI matrix rendered high specific capacitance and salient morphological features.

A Review of Battery Materials as CDI Electrodes for Desalination

The world is suffering from chronic water shortage due to the increasing population, water pollution and industrialization. Desalinating saline water offers a rational choice to produce fresh water thus resolving the crisis. Among various kinds of desalination technologies, capacitive deionization (CDI) is of significant potential owing to the facile process, low energy consumption, mild working conditions, easy regeneration, low cost and the absence of secondary pollution. The electrode material is an essential component for desalination performance. The most used electrode material is carbon-based material, which suffers from low desalination capacity (under 15 mg·g−1). However, the desalination of saline water with the CDI method is usually the charging process of a battery or supercapacitor. The electrochemical capacity of battery electrode material is relatively high because of the larger scale of charge transfer due to the redox reaction, thus leading to a larger desalination capacity in the CDI system. A variety of battery materials have been developed due to the urgent demand for energy storage, which increases the choices of CDI electrode materials largely. Sodium-ion battery materials, lithium-ion battery materials, chloride-ion battery materials, conducting polymers, radical polymers, and flow battery electrode materials have appeared in the literature of CDI research, many of which enhanced the deionization performances of CDI, revealing a bright future of integrating battery materials with CDI technology.

CuCo2 S4 -rGO Microflowers: First-Principle Calculation and Application in Energy Storage

This paper demonstrates the ability of a CuCo₂ S₄ -reduced graphene oxide (rGO) composite to perform robust electrochemical performances applying to supercapacitors (SCs) and lithium ion batteries (LIBs). The first-principle calculation based on density functional theory is conducted to study the electronic property of CuCo₂ O₄ and CuCo₂ S₄ and provide a theoretical basis for this work. Then, the 3D spinel-structured CuCo₂ O₄ and CuCo₂ S₄ microflowers are synthesized and compared as electrodes for both SCs and LIBs. The CuCo₂ S₄ microflowers can provide a larger specific surface area, which enlarges the contact area between the electrode material and the electrolyte and contributes to high-efficiency electrochemical reactions. The reduced graphene oxides are coated on the CuCo₂ S₄ microflowers, therefore effectively increasing the conductivity, and further absorbing the stress produced in the reaction process. As an electrode of a symmetric supercapacitor, the optimized CuCo₂ S₄ -rGO composite exhibits an energy density of 16.07 Wh kg^-1 and a maximum power density of 3600 W kg^-1 . Moreover, the CuCo₂ S₄ -rGO composite can also be used as an anode for lithium ion batteries, exhibiting a reversible capacity of 1050 mAh g^-1 after 140 cycles at the current density of 200 mA g^-1 . The galvanostatic intermittence titration techniques also reveal superior Li-ion diffusion behavior of the CuCo₂ S₄ -rGO composite during redox reactions.

Achieving Ultrahigh Cycling Stability and Extended Potential Window for Supercapacitors through Asymmetric Combination of Conductive Polymer Nanocomposite and Activated Carbon

Conducting polymers and carbon-based materials such as graphene oxide (GO) and activated carbon (AC) are the most promising capacitive materials, though both offer charge storage through different mechanisms. However, their combination can lead to some unusual results, offering improvement in certain properties in comparison with the individual materials. Cycling stability of supercapacitors devices is often a matter of concern, and extensive research is underway to improve this phenomena of supercapacitive devices. Herein, a high-performance asymmetric supercapacitor device was fabricated using graphene oxide–polyaniline (GO@PANI) nanocomposite as positive electrode and activated carbon (AC) as negative electrode. The device showed 142 F g⁻¹ specific capacitance at 1 A g⁻¹ current density with capacitance retention of 73.94% at higher current density (10 A g⁻¹). Most importantly, the device exhibited very high electrochemical cycling stability. It retained 118.6% specific capacitance of the starting value after 10,000 cycles at 3 Ag⁻¹ and with coulombic efficiency of 98.06 %, indicating great potential for practical applications. Very small solution resistance (Rs, 0.640 Ω) and charge transfer resistance (Rct, 0.200 Ω) were observed hinting efficient charge transfer and fast ion diffusion. Due to asymmetric combination, potential window was extended to 1.2 V in aqueous electrolyte, as a result higher energy density (28.5 Wh kg⁻¹) and power density of 2503 W kg⁻¹ were achieved at the current density 1 Ag⁻¹. It also showed an aerial capacitance of 57 mF cm⁻² at current 3.2 mA cm⁻². At this current density, its energy density was maximum (0.92 mWh cm⁻²) with power density (10.47 W cm⁻²).

Cobalt-Containing Nanoporous Nitrogen-Doped Carbon Nanocuboids from Zeolite Imidazole Frameworks for Supercapacitors

Pyrolyzing metal-organic frameworks (MOFs) typically yield composites consisting of metal/metal oxide nanoparticles finely dispersed on carbon matrices. The blend of pseudocapacitive metal oxides and conductive metals, as well as highly porous carbon networks, offer unique opportunities to obtain supercapacitor electrodes with mutually high capacitances and excellent rate capabilities. Herein, we demonstrate nitrogen-doped carbon nanocuboid arrays grown on carbon fibers and incorporating cobalt metal and cobalt metal oxides. This composite was synthesized via pyrolysis of a chemical bath deposited MOF, cobalt-containing zeolite imidazole framework (Co-ZIF). The active materials for charge storage are the cobalt oxide and nitrogen-doped carbon. Additionally, the Co metal and the nanoporous carbon network facilitated electron transport and the rich nanopores in each nanocuboid shortened ion diffusion distance. Benefited from these merits, our Co-ZIF-derived electrode delivered an areal capacitance of 1177 mF cm^-2 and excellent cycling stability of ~94% capacitance retained after 20,000 continuous charge-discharge cycles. An asymmetric supercapacitor prototype having the Co-ZIF-derived hybrid material (positive electrode) and activated carbon (negative electrode) achieved a maximal volumetric energy density of 1.32 mWh cm^-3 and the highest volumetric power density of 376 mW cm^-3. This work highlights the promise of metal-metal oxide-carbon nanostructured composites as electrodes in electrochemical energy storage devices.