Fiber Cathode Research Articles

Interface‐Engineered Dendrite‐Free Anode and Ultraconductive Cathode for Durable and High‐Rate Fiber Zn Dual‐Ion Microbattery

AbstractDespite the advantages of the fiber‐shaped Zn‐ion microbattery (FZMB) in powering wearable electronics, several fundamental challenges hinder its practical application, mainly including dendrite growth on Zn anodes (leading to short cycle life) and low electrical conductivity of cathode (resulting in poor rate performance). Herein, a facile approach of sputtering a nano‐thin conductive carbon layer on Zn anode to effectively suppress dendrite growth and a dual‐conductive polymer strategy to fabricate ultraconductive core‐sheath fiber cathode (poly(3,4‐ethylenedioxythiophene)‐poly(styrene sulfonate) (PEDOT:PSS) fiber@polyaniline nanobulges) are demonstrated. The carbon layer suppresses Zn dendrites by uniformizing surface electric field and providing abundant nucleation sites. The superior conductivity of the cathode is inherited from two conductive polymers (in particular, PEDOT:PSS fibers have an ultrahigh conductivity of 3676 S cm−1) and their strong intermolecular interactions. The resulting FZMB shows excellent stability (over 100% capacity retention after 3000 cycles) and supercapacitor‐level rate performance (73% capacity retention from 0.1 to 10 A g−1). Kinetics and mechanism studies reveal that the surface‐controlled dual‐ion migration mechanism is also correlated with the high rate performance. The corresponding quasi‐solid‐state device exhibits high stability under extreme deformation conditions and superior water‐proof capability (94.6% capacity retention after 12 h underwater immersion), demonstrating great practical application potential.

High-performance wire-shaped aluminum ion batteries based on continuous graphene fiber cathodes

Due to their high capacity and cyclic stability, aluminum ion battery (AIB) shows great potential to be used as efficient energy storage system for various electronics. However, the aluminum ion batteries with a typical planar structure greatly limit their practical applications in the fields of flexible and wearable electronics towards intelligence, miniaturization and portability. Herein, we demonstrate a novel wire-shaped aluminum ion battery, which is fabricated with graphene fiber (GF) as cathode and aluminum (Al) wire as anode. The developed Al/GF battery not only delivers a high specific capacity of 115 mAh g−1, but also exhibits excellent rate capability and cycling stability after 1000 charge-discharge under high current density of 50 A g−1. Due to the unique structure, the developed wire-shaped battery can well maintain their original electrochemical performance under different bending states and even after hundreds of bending cycles, suggesting outstanding mechanical flexibility and stability. The flexible wire-shaped aluminum ion battery is a promising candidate to be used as power supplies for flexible and portable electronics.

Electrospun Core–Shell Fibers for High-Efficient Composite Cathode-Based Solid Oxide Fuel Cells

Fibrous perovskite oxide has been the most promising cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs) due to its efficient mass and charge transfer. Herein, a core–shell fiber-structured YCo0.5Fe0.5O3 (YCF)–Gd0.1Ce0.9O1.95 (GDC) cathode is synthesized via the modified electrospinning technique. These unique YCF–GDC fibers exhibit a uniform diameter of 300 nm, and the GDC particles are attached to the YCF fiber cores. The electrochemical performance demonstrates a relatively low area-specific resistance of 0.66 Ω·cm2 at 550 °C in air, which is much lower than 1.56 Ω·cm2 of pure YCF fiber cathode. Moreover, the distribution of relaxation times (DRT) analysis results indicate that the introduction of GDC nanoparticles and the core–shell structure greatly facilitate oxygen-ion conduction and charge transfer processes, and the oxygen incorporation process plays a major role in the total polarization resistance. The NiO–GDC|GDC|fibrous YCF–GDC fuel cell shows a maximum power density of 426.5 mW·cm–2 at 550 °C. These results display that the core–shell fiber-structured YCF–GDC composite oxide is a promising candidate of highly active cathode for IT-SOFCs.

Electro-Fenton oxidation of a β-lactam antibiotic cefoperazone: Mineralization, biodegradability and degradation mechanism

Oxidation of a commonly-used β-lactam pharmaceutical, cefoperazone (CFPZ), was systematically investigated by anodic oxidation (AO), AO in presence of H2O2 electro-generation (AO-H2O2) and electro-Fenton (EF) processes with an activated carbon fiber cathode from the biodegradability viewpoint. The degradation and mineralization rates increased in a sequence of AO < AO-H2O2 < EF. Even CPFZ could be efficiently degraded in EF process, achieving complete CFPZ mineralization was rather difficult. Thereby, the biodegradability of the effluent after electrochemical pretreatment was examined to test the feasibility of the combination of electrochemical and biological processes. The results suggested that compared with AO and AO-H2O2, EF process could effectively transform the non-biodegradable CFPZ into biocompatible materials with a high BOD5/COD value (0.33 after 720 min), allowing the possible biotreatment for further remediation. This behavior was relatively accorded with the average oxidation state (AOS) results, evidencing the potential of EF process in enhancing the biodegradability of CFPZ. The determination of inorganic ions revealed that N in CFPZ molecular was oxidized into NH4+ and NO3− ions in EF process. Oxalic, succinic, oxamic, fumaric and formic acids were also formed. Besides, six aromatic by-products were qualified and a possible pathway involving hydrolysis, hydroxylation and decarboxylation during CFPZ mineralization was proposed.

Photo-electrochemical Osmotic System Enables Simultaneous Metal Recovery and Electricity Generation from Wastewater.

Global depletion of natural resources provides an impetus for developing low-cost, environmentally benign technologies for the recovery of valuable resources from wastewater. In this study, we present an autonomous photo-electrochemical osmotic system (PECOS) that can recover a wide range of metals from simulated metal-laden wastewater with sunlight illumination while generating electricity. The PECOS comprises a draw solution chamber with a nickel nanoparticle-functionalized titanium nanowire (Ni-TiNA) photoanode, a feed solution chamber containing synthetic wastewater with an immersed carbon fiber cathode, and a forward osmosis (FO) membrane mounted between the chambers as a separator. Using a Na2-EDTA anolyte as a draw solution at neutral pH, we demonstrate that a sunlit PECOS achieves copper recovery at a rate of 51 g h-1 per m-2 of membrane area from simulated copper-laden wastewater while simultaneously producing a maximum power density of 228 mW m-2. Moreover, because of the osmotic pressure difference generated by the photo-electrochemical reactions, the PECOS reduces the wastewater volume by extracting fresh water through the FO membrane at a water flux of 0.84 L m-2 h-1. We further demonstrate the feasibility of the PECOS in recovering diverse metals from a simulated metal-laden industrial wastewater under sunlight irradiation. Our proof-of-concept PECOS prototype provides a sustainable technological solution that leverages sunlight in an electrochemical osmotic system to recover multiple resources from wastewater.

Improving electrochemical performance of lithium ion batteries using a binder-free carbon fiber-based LiNi0.5(1-x)Mn1.5(1-x/3)CrxO4 cathode with a conventional electrolyte

A binder-free LiNi0.5(1-x)Mn1.5(1-x/3)CrxO4 (Cr-doped LNMO)/carbon fiber (CF) cathode with carbon paper as the current collector is developed via a process that involves electrochemical deposition, hydrothermal reaction, and vacuum filtration. The composite material properties are thoroughly characterized using scanning electron microscopy/transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The Cr-doped LNMO active materials are composed of submicron particles with polyhedral and spinel crystal structures with good crystallinity. The LiNi0.5(1-x)Mn1.5(1-x/3)CrxO4 (x = 0.2) configuration is found to have a higher Mn4+/Mn3+ ratio and is capable of delivering a reversible capacity of ~137 mAh g−1 at 0.2 C, due to the active Ni2+/Ni3+/Ni4+ and Cr3+/Cr4+ redox reactions. Furthermore, it exhibits an enhanced rate capability with 118 mAh g−1 at 5 C. This is evidenced by a reduction in charge transfer resistance at the solid/electrolyte interface, and accelerated ion diffusion in the host material corresponding to a high degree of cation disordering in Cr-doped LNMO. Overall, the binder-free electrode, which integrates Cr-doped LNMO and a 3D CF-based framework, facilitates the electrochemical activity of the active material. This leads to improved cycling stability with 99% capacity retention over 200 cycles against high voltage (4.9 V vs. Li/Li+).

Sm0.5Sr0.5CoO3-Sm0.2Ce0.8O2 Nano Composite Fiber Cathode for Solid Oxide Fuel Cells for Solid Oxide Fuel Cells

Solid oxide fuel cells have been considering as an energy conversion device due to their fuel flexibility and high energy conversion efficiency. However, because the high operation temperature of SOFC has caused limitation and instability of the materials, many research groups focus on lowering the operation temperatures [1,2]. In SOFC system, to achieve superior cell performance at low temperature, several issues such as deterioration of electrode’s ionic conductivity and oxygen reduction reaction kinetics should be considered [3,4]. In order to solve these problems, nanocomposite materials introduced hetero interface have been studied on cathode [5-7]. In this study, electrospinning method was used to produce fibrous composite consisting of Sm0.5Sr0.5CoO3-δ (SSC) and Sm0.2Ce0.8O2-δ (SDC). From the XRD and SEM analysis, the lattice strain without the secondary phase occurred and the well-attached interface in microstructure was confirmed. Our designed composite structure as cathode was employed to cause lattice strain that enhances the diffusion of oxygen ion as well as improving the cell performance due to its excellent microstructure.

Research progress of fiber-shaped electrochemical energy storage devices

During the past two decades, wearable devices have been broadly used for a variety of fields such as biomedical system, communication and microelectronics. The power system such as lithium-ion batteries is essential to the operation of wearable devices, which should adapt to irregular substrates and sustain complex deformations. A promising strategy is to fabricate high-performance energy storage devices in a fiber shape, e.g., fiber lithium-ion batteries (LIBs). These fiber LIBs with diameters ranging from tens to hundreds of micrometers can be readily integrated with human body and work stably under constant body motions. They can also be woven into breathable fabrics to satisfy the needs of wearable electronics. The key challenges facing fiber LIBs include effective loading of active materials on fiber electrodes, efficient charge transfer along fiber electrodes and interface stability of fiber electrodes under operation and deformation. Fiber electrodes are thus designed with hierarchical and aligned channels to effectively load active materials, so an effective electric field can be established between the fiber cathode and anode. Aligned carbon nanotubes (CNTs) can be made with conductive additives and active materials into fiber electrodes by a continuous spinning process. Conventional metal current collectors, binders and conductive agents are not required, and active materials may reach 90% of the electrode by weight. The resulting hierarchically helical CNT fiber electrode shows high flexibility, high strength, and high electrical conductivity. The flexural rigidity is as low as 10−7 nN/m2, which is several orders of magnitude lower than those of ordinary synthetic fibers. The specific strength reaches 107 Nm/kg, which is higher than those of ordinary synthetic fibers. The conductivity reaches 104 S/cm, which can meet the needs of batteries. The aligned CNT composite fiber permits efficient electron transport, where the electrons hop among neighboring CNTs. Besides, due to the capillary force, the electrolyte can penetrate throughout the entire fiber via micrometer-sized and nanometer-sized channels, benefiting ion transport. The twisted CNT bundles firmly bind active materials and prevent their significant volume variations during charge and discharge processes. Therefore, the efficient conductive pathways can be maintained to deliver both high rate and cyclic stability. Fiber LIBs could be fabricated by assembling two fiber electrodes in parallel, twisting or coaxial structure. Gel electrolyte avoids the potential safety risks stemmed from liquid electrolytes. The continuously fiber LIBs show both high flexibility and energy storage capacity. After bending for 100000 cycles, the capacities have been well maintained, and the energy densities exceed 100 Wh/kg. Based on the similar strategy, a series of fiber energy storage devices such as supercapacitors, lithium-sulfur batteries, lithium-air batteries, zinc-ion batteries, zinc-air batteries and aluminum-air batteries, have been also produced. To summarize, fiber energy storage devices can be woven into flexible fabrics or integrated with energy harvesting devices to satisfy the next-generation electronics. Such a new strategy establishes an efficient avenue to particularly accelerate the development of wearable electronics in the future.

Dye degradation and kinetics of online Electro-Fenton system with thermally activated carbon fiber cathodes

Abstract In this study, the effect of the gas type (N2 or CO2) and activation time (0−10 h) on the thermal activation of carbon fiber (CF) electrodes being used as the working electrodes was tested in an Electro-Fenton (EF) system with Pt anodes; this was aimed at achieving the total organic carbon (TOC) removal for the Acid Orange 7 (AO7) dye. An EF experimental system was established to perform online analyses that were different from the majority of those in the literature. Furthermore, to test the effectiveness of the EF process parameters, the cathodic potential (0.5–2.5 V) and Fe2+ concentration (0.2−1 mM) were investigated. The initial solution dye concentration (0.1 mM), pH (3), and electrolyte concentration (50 mM) were held constant in this study. In an undivided glass reactor, dry air was supplied (16 L/h) to the system in batch mode, and a 600-ml dye solution was added. The optimum dye and TOC removal efficiencies at 0.8 V with 0.3 mM of Fe2+ by using CF activated at 900 °C under N2 for 5 h were 92.9 % at 15 min and 84.0 % at 120 min. In contrast, a kinetic analysis was performed using data from an online analysis system. Accordingly, the kinetic study of the degradation reaction was evaluated in two stages, namely, for the first 3.2 min and for the subsequnet time frame. In addition, the CF electrode was found to be a promising electrode for electro-oxidation systems, with augmentaions in the electroactive surface area and crystallite size by 46.64 % and 17.15 %, respectively.

Effective Electro-Fenton Treatment for a Real Textile Effluent: A Case Study

In this study, a real textile effluent (RTE) was treated by the electro-Fenton method in a parallel plate reactor. A carbon fiber cathode and a stainless-steel mesh anode were used as electrodes. The effluent was characterized, and dilute solutions were prepared with initial chemical oxygen demand (COD) concentrations of 50, 100, 200, 250, and 300 ppm. The prepared effluents were degraded for 180 min, at an applied voltage of 1.8 V and a current density of 0.45 mAcm−2. Reductions of more than 85 % of the initial color and 55 % of the COD were achieved. The energy consumption was 7 kW h kgCOD−1 removed. The RTE degradation followed pseudo-first-order kinetics, and its rate constants ranged from 0.01 to 0.02 min−1. It was observed that the degradation rate decreased as the initial effluent concentration increased.Based on the kinetic results, a methodology was developed to predict the effluent degradation. For each kinetic equation, the empirical constant (a) and the rate constant (k) were determined. Mathematical models were formulated for a and k, relative to their respective CODi concentrations, with a correlation coefficient greater than 0.95 in both cases. The theoretical values of at and kt for the working concentrations were calculated using the formulated mathematical models. The theoretical parameters were substituted into the first-order kinetic equation, allowing the simulation of the RTE degradation. The degradation behavior was simulated for each of the five concentrations studied, and the results compared with the experimental results. The theoretical and experimental values showed a high degree of adjustment, demonstrating that the proposed methodology was successful in predicting the degradation of the textile effluent.

Role of carbon fiber electrodes and carbonate electrolytes in electrochemical phenol oxidation

In-situ chemical oxidation (ISCO) requires an injection of oxidants into a contaminated site. However, the oxidants decompose and react with contaminants during transport to the contaminated region, which causes oxidant over-consumption. In-situ oxidant generation can solve this problem, and electrochemical methods can be applied to achieve this. Electrochemical oxidation is highly dependent on electrode material type. In this study, we evaluated graphite and carbon fiber as candidates for electrochemical oxidant generation and phenol as the model compound. The carbon fiber anode oxidized the phenol more effectively than graphite, with removal proportional to the applied current. Carbonate electrolytes were more effective at oxidizing phenols than sulfate electrolytes. The faster carbon fiber anode phenol oxidation is due to its large surface area. Carbonate radicals in the carbonate electrolyte contribute to phenol oxidation as well as further intermediate oxidation. The carbon fiber cathode was not an effective phenol oxidizer even though it generated more hydrogen peroxide. This is because there was no catalyst to transform the hydrogen peroxide into hydroxyl radicals. Results indicate that electrochemical oxidation using carbon fiber is an effective method for treating phenol found in groundwater with high concentrations of (bi)carbonate.

Evaluation of the stability of polyacrylonitrile-based carbon fiber electrode for hydrogen peroxide production and phenol mineralization during electro-peroxone process

This study evaluated the stability of polyacrylonitrile-based carbon fiber cathode for hydrogen peroxide (H2O2) production and phenol mineralization during multiple cycles of electro-peroxone (E-peroxone) process. Results show that the oxidation of bulk carbon fiber by electro-generated H2O2 and bubbled ozone (O3) is negligible during the E-peroxone process. Nevertheless, the carbon fiber surface was oxidized to some extent as the cathode was repeatedly used in the multi-cycle E-peroxone process. Due to the oxidation by H2O2 and O3, nitrogen-containing groups on the carbon fiber surface were converted from pyridinic-N to pyridonic-N during the E-peroxone process. These changes resulted in an increase in the activity of the cathode for oxygen reduction reaction (ORR), but a decrease in the selectivity of the cathode for two-electron ORR to H2O2. After the carbon fiber cathode was used for 30 cycles of the E-peroxone treatment of phenol solutions, the cathodic potentials for ORR shifted positively by ~450 mV, which is beneficial to reduce the energy consumption of electrochemical H2O2 production. Nevertheless, the apparent current efficiency (ACE) for H2O2 production decreased from ~91.5% for the virgin cathode to ~48.2% for the used cathode. Despite the decrease in the ACE for H2O2 production, sufficient amounts of H2O2 could still be produced during the E-peroxone process with the used cathode. Therefore, complete phenol mineralization was maintained during all 30 cycles of the E-peroxone treatment of phenol solutions. These results suggest that the polyacrylonitrile-based carbon fiber is a promising cathode material for long-term E-peroxone operations.

Submicrosecond electron accelerator based on pulsed transformer

The article describes the test results of a submicrosecond electron accelerator based on a high-voltage pulse transformer. The transformer uses a self-supporting coil design with transformer oil insulation, which ensures high reliability of the device. A transformer-based high-voltage generator produces voltage pulses with an amplitude up to 475 kV, a pulse duration of 0.25 μs (FWHM) with a repetition rate up to 5 pps. A vacuum electron diode with a carbon fiber cathode is installed directly at the generator output and provides electron beam current amplitude up to 1.5 kA in the accelerating gap. An exit window with a titanium membrane 60μm thick is used to output the electron beam into the atmosphere. The exit window can be replaced by a converter to generate pulsed bremsstrahlung X-rays. The accelerator is designed to carry out research in the fields of studying the properties of materials in extreme conditions and the practical application of a pulsed electron beam.

A flow-through electro-Fenton process using modified activated carbon fiber cathode for orange II removal

This study investigated the removal of Orange II by an electro-Fenton process using a novel recirculation flow-through reactor. The hydrogen peroxide was generated in-situ on the activated carbon fiber (ACF) modified with carbon black and polytetrafluoroethylene (PTFE). The modified ACF cathode was characterized by scanning electron microscopy (SEM) and nitrogen adsorption-desorption study. In light of the production of H2O2 and removal of Orange II, the optimum weight percentage of PTFE in the mixture of carbon black and PTFE was 75%. The effects of some important operating parameters such as current and flow rate were investigated. The best Orange II removal reached 96.7% with mineralization efficiency of 55.4% at 120 min under the current of 100 mA, initial pH 3, Fe2+ 0.3 mM and the flow rate of 7 mL min−1. The cathode exhibited good regeneration ability and stability. OH was proved to be the main oxidizing species in this flow-through electro-Fenton system. This work demonstrated that such electro-Fenton process using modified ACF cathode was promising for the degradation of organic pollutants.

Field emission microscopy of carbon nanotube fibers: Evaluating and interpreting spatial emission

In this work, the authors quantify field emission properties of cathodes made from carbon nanotube (CNT) fibers. The cathodes were arranged in different configurations to determine the effect of cathode geometry on the emission properties. Various geometries were investigated including (1) flat cut fiber tip, (2) folded fiber, (3) looped fiber, and (4) fibers wound around a cylinder. The authors employ a custom field emission microscope to quantify I-V characteristics in combination with laterally resolved field-dependent electron emission area. Additionally, they look at the very early emission stages, first when a CNT fiber is turned on for the first time, which is then followed by multiple ramp-up/down runs. Upon the first turn on, all fibers demonstrated limited and discrete emission area. During ramping runs, all CNT fibers underwent multiple (minor and/or major) breakdowns, which improved emission properties in that turn-on field decreased and field enhancement factor and emission area both increased. It is proposed that breakdowns are responsible for removing initially undesirable emission sites caused by stray fibers higher than average. This initial breakdown process gives way to a larger emission area that is created when the CNT fiber subcomponents unfold and align with the electric field. The authors' results form the basis for careful evaluation of CNT fiber cathodes for dc or low frequency pulsed power systems in which large uniform area emission is required or for narrow beam high frequency applications in which high brightness is a must.

Wet-spinning assembly and in situ electrodeposition of carbon nanotube-based composite fibers for high energy density wire-shaped asymmetric supercapacitor

Wire-shaped supercapacitors (WSC) have attracted tremendous attention for powering portable electronic devices. However, previously reported WSC suffered from a complicated fabrication process and high cost. The objective of this study is to develop a facile and scalable process for the fabrication of high energy density WSC. We coupled the wet-spinning assembly with an in situ electrodeposition technique to prepare carbon nanotube (CNT)-based composite fibers. The charge balance between the electrodes was realized by controlling the deposition time of the pseudocapacitive materials. A wire-shaped asymmetric supercapacitor (WASC) was fabricated by twisting MnO2/CNT fiber cathode and PPy/CNT fiber anode with LiCl/PVA electrolyte. The flexible MnO2/CNT//PPy/CNT WASC operated in a broadened voltage range of 0–1.8 V exhibited a high capacitance of 17.5F cm−3 (10.7F g−1). In addition, it delivered a maximum energy and power densities of 7.88 mWh cm−3 (4.82 Wh kg−1) and 2.26 W cm−3 (1382 W kg−1), respectively. The WASC device demonstrated satisfactory cycling stability with 86% capacitance retention, and its Coulombic efficiency remained at 96% after 5000 charge–discharge cycles. The contributions of the diffusion-controlled insertion and the surface capacitive effect were theoretically quantified to investigate the energy storage mechanism. The fabrication approaches hold potential for the construction of cost-effective and high-performance WSC.

Hybrid disorder carbon fiber cathode for high current pulsed electron beam emission

Cathode plays a paramount function in high current pulsed electron beam (HCPEB). Herein, a novel design of cathode with hybrid short carbon fiber (SCF) and carbon fiber powder (CFP) was developed. The surface morphology of cathode with varied CFP additions was characterized by confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM) and atomic force microscope (AFM). Electrical property and electron beam emission property of different cathodes were investigated. Results revealed that the microstructure of the cathode presented disorder contact structure, the conductive network became denser and the micro-protrusions on the cathode surface were remarkably increased through the moderate addition of CFP. Notably, the cathode by adding 1.5 vol% of CFP manifested the least electrical resistance 1.2 Ω and showed the best electron beam emission performance with beam spot diameter 50 mm at a plateau duration 1.6 μs. Moreover, there was no obvious damage occurred on the surface of cathode (1.5 vol%) after 1000 electron beam emission, which exhibited long lifetime. This study provided an insight for the development of HCPEB cathode.

Instability of the field emission current from carbon fiber cathodes

Instability of the field emission current from carbon fiber cathodes

Recovery of Phosphorus from Hypophosphite-Laden Wastewater: A Single-Compartment Photoelectrocatalytic Cell System Integrating Oxidation and Precipitation.

Recovery of phosphorus through precipitation from hypophosphite-laden wastewater is more difficult than from orthophosphate-laden wastewater because of the higher solubility of hypophosphite (H2PO2-). Herein, a single-compartment photoelectrocatalytic (PEC) cell system consisting of a TiO2/Ni-Sb-SnO2 bifunctional photoanode and an activated carbon fiber (ACF) cathode with dosing Fe2+ ions was developed for recovery of phosphorus in the form of FePO4 from hypophosphite-laden wastewater. In the PEC process, H2PO2- with an initial concentration of 1.0 mM was completely oxidized and recovered within 30 min at 3.0 V, and the pseudo-first-order rate constant of H2PO2- oxidation was ∼4 times than that in the electrocatalytic process and even ∼89 times than that in the photocatalytic process. The bifunctional photoanode can simultaneously generate •OH radicals and O3; the ACF cathode can electrogenerate H2O2; H2O2, O3, and the added Fe2+ can interact with each other to produce •OH radicals and Fe3+ ions. •OH radicals mainly from the Fenton process were responsible for oxidation of H2PO2- to PO43-, which immediately combined with Fe3+ to form FePO4 at the optimized conditions to realize recovery of phosphorus. The long-term stability of this system was demonstrated. The efficiency for actual electroless nickel plating effluents was exhibited.

Flexible aqueous ammonium-ion full cell with high rate capability and long cycle life

Aqueous full cell based on non-metal NH4+ ions redox reactions has been reported recently owing to NH4+ ions as charge carriers with advantages of abundant resources, light weight, eco-friendly and fast diffusion capability. However, the exploration of NH4-ions full cell is still in its infancy. Despite the aforementioned unique properties of the aqueous NH4-ions full cell, there is almost no reported about the flexible NH4-ions full cell so far. Developing novel electrodes with highly reversible NH4-ions accommodation capability underlies the construction of high-performance full cells. Here, we first demonstrate a novel flexible aqueous ammonium-ion full cell with high rate capability and long cycle life consisted of urchin-like NH4V4O10 coated on carbon fiber cathodes and polyaniline nanorods grown on carbon fiber anodes in (NH4)2SO4 aqueous solution. A high specific capacity up to 167 mA h g−1 at a current density of 0.1 A g−1, excellent rate capability with a specific capacity of 54 mA h g−1 at 1 A g−1 and an ultralong cycle life with a high capacity retention are achieved. Meanwhile, the NH4-ion full cell shows good flexibility with well-maintained electrochemical performances at different deformation states. This work may shed a light on developing flexible aqueous NH4-ion cells.