Showing papers in "Ionics in 2021"
TL;DR: Findings indicate that the novel carbonization technology in this study can not only be used to obtain high-performance supercapacitor electrode materials but also provide a new idea for the recycling and utilization of wastes such as medical devices.
Abstract: The spread of COVID-19 has led to an explosive increase in the number of waste polypropylene face masks worldwide, landfill and incineration of which will cause serious pollution and resource waste. This study aims to develop a new method for the safe and high-added value reuse of materials for polypropylene face masks based on carbonization of porous polymer. The waste masks were first sulfonated in an autoclave, then used as carbon source and turned into a dense hollow fiber porous structure after a one-step heat treatment. This porous structure has a high specific capacitance, namely 328.9 F g-1 at a current density of 1 A g-1. Besides, the assembled solid-state capacitor possesses a good energy density of 10.4 W h kg-1 at a power density of 600 W kg-1, and excellent cycling stability with a capacitance retention rate of 81.1% after 3000 cycles. These findings indicate that the novel carbonization technology in this study can not only be used to obtain high-performance supercapacitor electrode materials but also provide a new idea for the recycling and utilization of wastes such as medical devices.
46 citations
TL;DR: In this article, a one-step environmentally benign procedure for preparing nitrogen-doped graphene electrodes for high performance supercapacitors has been demonstrated for the first time, called Yucel's method.
Abstract: In this work, a novel one-step environmentally benign procedure for preparing nitrogen-doped graphene electrodes for high performance supercapacitors has been demonstrated for the first time, called Yucel’s method. N-doped graphene-based electrodes were synthesized in a short time, at room temperature, one step (no need for a second process for doping) and low-cost by the using of Yucel's method without harmful oxidizing and reducing chemicals. During the production of N-doped graphene-based electrodes by this method, which functional group will form on the graphene surface is determined by controlling the applied potential range. Also, a detail mechanism has been proposed for the incorporation of these functional groups on the graphene structure produced by Yucel’s method for the first time in literature. Since the chemical and morphological structure of each electrode is different, specific capacitance values are also different. The electrodes synthesized in a narrower synthesis potential range have shown higher capacity thanks to the catalytic effects of oxygenated functional groups (NO2, ▬COOH, ▬OH etc.) on their surfaces. Indeed, the relations between N including functional groups and specific capacitance properties of the electrodes were investigated in detail. After electrochemical, spectroscopic, and microscopic characterization of the materials, cyclic charge–discharge tests were carried out for 1000 cycles. The specific capacitance of the electrodes changed from 178 mF.cm−2 to 2034 mF.cm−2 in 10 mA.cm−2 current density as a function of the mesoporous structure. This structure type becomes more accessible for electrolyte penetration as the number of cycles increases.
40 citations
TL;DR: In this article, a Ni-based metal-organic framework (Ni-MOF) modified electrode was fabricated for electrochemical detection of dopamine, which was synthesized by ionothermal synthesis method using an ionic liquid as a template.
Abstract: A Ni-based metal-organic framework (Ni-MOF) modified electrode was fabricated for electrochemical detection of dopamine. The Ni-MOF was synthesized by ionothermal synthesis method using an ionic liquid as a template. The morphology and composition of the Ni-MOF were characterized by scanning electron microscope, X-ray diffraction, thermogravimetric analysis, and attenuated total reflection Fourier transform infrared spectroscopy. Electrochemical responses of the Ni-MOF modified electrode toward dopamine were performed using differential pulse voltammetry. The electrochemical sensing performance of the Ni-MOF modified electrode toward dopamine was improved by the introduction of ionic liquid with a wide linear range (0.2–100 μmol L−1), and a low detection limit (60 nmol L−1). Further studies indicated that the modified electrode exhibited great selectivity to dopamine in complex mixtures, and the Ni-MOF modified electrode also has excellent stability and reproducibility. Moreover, the analysis of real samples confirmed that the modified electrode has a certain reliability.
34 citations
TL;DR: In this article, a simple hydrothermal route using urea as both a stabilizing and structure-directing agent for supercapacitor application is described, where the MnCo2O4 nanorods are prepared by a simple Hydrothermal approach using urene as both stabilizer and structure directing agent, and the morphological features of the prepared materials were characterized by a scanning electron microscope (SEM) and transmission electron microscope.
Abstract: In this work, the MnCo2O4 nanorods are prepared by a simple hydrothermal route using urea as both a stabilizing and structure-directing agent for supercapacitor application. The morphological features of the prepared materials were characterized by a scanning electron microscope (SEM) and transmission electron microscope (TEM). The chemical and the crystal structure were studied using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analysis. The morphological analysis showed rod-like structures with a diameter of 50–60 nm and length of 1–2 μm respectively. The XRD pattern showed that the particles are crystalline and belong to the cubic spinel structure. The chemical composition was inferred from the XPS analysis. The formation of metal-oxygen bond is inferred using FTIR, and BET showed a high surface area of 41.80 m2g−1. The electrochemical characterization of MnCo2O4 nanorods was performed in 2 M KOH solution using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and impedance analysis. The CV studies showed a pseudocapacitance behaviour of the electrode, and the GCD studies revealed a specific capacitance of 187.5 Fg−1 at a current density of 0.25 Ag−1. The electrode exhibited good cyclic stability by retaining 90% of the initial value after 5000 cycles. The specific capacitance was also estimated from the impedance analysis and the pseudocapacitive nature of the MnCo2O4 electrode was analysed. Further, the fabricated asymmetric supercapacitor (ACǁ MnCo2O4 nanorods) provides the specific capacitance of 76 Fg−1 at a current density of 0.25 Ag−1. The results indicate that the MnCo2O4 can be a promising candidate for supercapacitor application.
29 citations
TL;DR: In this article, the authors review the research progress of polyimide separators in the field of energy storage, focusing on PI separators containing different groups and compounding with different substances.
Abstract: Polyimide (PI) is a kind of favorite polymer for the production of the membrane due to its excellent physical and chemical properties, including thermal stability, chemical resistance, insulation, and self-extinguishing performance. We review the research progress of PI separators in the field of energy storage—the lithium-ion batteries (LIBs), focusing on PI separators containing different groups and compounding with different substances. This review will help to optimize the PI separator material for the LIBs and favor understanding the preparation-groups, structure-performance relationship of porous separators in LIBs. Therefore, the advantages of PI separators in lithium-ion batteries are introduced in detail and the development of PI separators to the lithium-ion batteries is prospected.
29 citations
TL;DR: In this article, the Na3V2(PO4)3 (NVP) and its binary-doped Na2.96K0.04V1.93Zr0.0525(PO 4)3/C were analyzed by XRD, XPS, SEM, and electrochemical tests.
Abstract: The Na3V2(PO4)3 (NVP) and its binary-doped Na2.96K0.04V2-xZr(3/4)x(PO4)3/C are prepared by a facile solid-phase method. The crystal structure, morphological characteristics, and electrochemical properties are analyzed by XRD, XPS, SEM, and electrochemical tests. The results reveal that K+ and Zr4+ have been successfully doped into NVP system without damaging the original structure. The co-doping strategy can broaden the channels of Na+ migration to facilitate the ionic conductivities. Meanwhile, it is beneficial to stabilizing the crystal structure effectively by introducing the K+ and Zr4+ with larger ionic radius. All the electrochemical properties of co-doped system are better than that of NVP, resulting from the lager channel for Na+ diffusion and enhanced intrinsic electrical conductivities by co-doping. Notably, Na2.96K0.04V1.93Zr0.0525(PO4)3/C exhibits the best electrochemical performance. It delivers a high discharge capacity of 107.3 mAh g−1 at 0.1 C; it remains 92.3 mAh g−1 after 400 cycles at 2 C, corresponding to the capacity retention of 92.02%; it still maintains 100.0 mAh g−1 even at 10 C rate.
27 citations
TL;DR: In this paper, various methods to achieve optimum porosity of WO3 films leading to best electrochromic performance are also discussed, which can be considered as one of the pivotal facets of functionalized ECC thin films.
Abstract: Transition metal oxides have gained substantial attention in the previous decade by virtue of their distinctive physical and chemical properties. Amidst all, tungsten oxide (WO3) is emerging as distinct metal oxide on account of its outstanding electrochromic performance. Furthermore, optical-switching speed has topmost importance in the actual device. The sole approach to enhance this attribute is to escalate surface area of the electrochromic coatings, which can be done by instigating porosity within bulk material. Porosity can be considered as one of the pivotal facets of functionalized electrochromic thin films. Cations can be made to get transported into the depth of the host with the presence of high porosity in a structure. This featured article is attempting to pivot the path as how porosity is upgrading the electrochromic attribute of WO3 films. Furthermore, various methods to achieve optimum porosity of WO3 films leading to best electrochromic performance are also discussed.
26 citations
TL;DR: In this article, a solid polymer electrolyte of carboxymethyl cellulose (NaCMC) doped with sodium nitrate (NaNO3) was developed by solution casting method.
Abstract: Na+ ion-conducting solid polymer electrolyte (SPE) of sodium salt of carboxymethyl cellulose (NaCMC) doped with sodium nitrate (NaNO3) was developed by solution casting method. FTIR technique confirmed the formation of hydrogen bonding between $$ {NO}_3^{-} $$
anion and functional groups of NaCMC. XRD study revealed the low degree of crystallinity that reduced upon doping. Impedance spectroscopy was adapted in order to analyze the conductivity and dielectric relaxation phenomena of the polymer-salt complex. FTIR deconvolution technique was employed to understand the factor that influences the ionic conductivity in SPE; concentration of mobile ions and ionic mobility both play a vital role. Ion transference number has been found out to be > 0.97 for all samples indicating that the conducting species are primarily ions. The highest ionic conductivity of 3 × 10−3 Scm−1 with the mechanical strength of 30.12 MPa was achieved for a host containing 30 wt.% NaNO3 at ambient temperature.
18 citations
TL;DR: In this article, an e-MnO2 was synthesized and applied to the cathode material of Zn-ion batteries, which exhibits a high specific capacity of 465 mAh g−1 at 0.2 C, high energy density (620 Wh kg−1) and excellent cycle stability.
Abstract: Aqueous zinc-manganese dioxide batteries (Zn-MnO2) are gaining considerable research attention for energy storage taking advantages of their low cost and high safety. Polymorphic MnO2 (α, β, γ, δ, λ, and amorphous) has been extensively studied, but reports of akhtenskite MnO2 (e-MnO2) are limited and the performance of e-MnO2-based ZIBs existing is not very excellent. Here, e-MnO2 was synthesized and applied to the cathode material of Zn-ion batteries. It exhibits a high specific capacity of 465 mAh g−1 at 0.2 C, high energy density (620 Wh kg−1) and excellent cycle stability (the capacity increases from 312 to 435 mAh g−1 after 150 cycles at 1 C). Its good electrochemical performance laid a solid foundation for its further research and large-scale use in zinc-ion batteries.
17 citations
TL;DR: In this article, the effect of inorganic fillers on lithium-ion migration in polymer electrolyte is analyzed and the latest research progress of solid composite electrolyte based on polyethylene oxide, polyacrylonitrile, and polycarbonate is introduced.
Abstract: Solid electrolyte is an important part of all-solid-state lithium-ion battery, and it is the key and difficult point in the research of all-solid-state lithium-ion battery. Both solid polymer electrolyte and inorganic ceramic electrolytes have obvious deficiencies in electrochemical and mechanical properties, but polymer-inorganic filler solid composite electrolyte is obtained by adding inorganic filler into solid polymer electrolyte and this way can complement their shortcomings. In this paper, the effect of inorganic fillers on lithium-ion migration in polymer electrolyte is analyzed. The latest research progress of solid composite electrolyte based on polyethylene oxide, polyacrylonitrile, and polycarbonate is introduced, which provides guidance for the research of solid composite electrolyte in the future.
16 citations
TL;DR: In this article, an improved HIf-based state of charge estimation algorithm is proposed, which incorporates a sliding mode observer, yielding better estimation stability and accuracy than conventional HIf.
Abstract: H-infinity filter (HIf) is widely used in state of charge (SOC) estimation of lithium-ion batteries due to its superior performance to extended Kalman filter (EKF) whose robustness is weak. In this paper, an improved HIf-based SOC estimation algorithm is proposed, which incorporates a sliding mode observer, yielding better estimation stability and accuracy than conventional HIf. The proposed algorithm takes advantages of HIf and sliding mode observer that it is more robust to the modeling error and noises. Samsung ICR18650 lithium-ion battery cell is tested and results show that the proposed method improves SOC estimation accuracy, two error indicators are evaluated and both are reduced compared to that of the EKF and HIf.
TL;DR: In this article, the Ni-Co-Mn0.25 MOF was synthesized through an effortless one-step hydrothermal method, in which multiple metal nodes were evenly distributed between metal organic frameworks (MOF) through ligands and formed a multiphase nanostructure through synergy.
Abstract: Design and construction of multiphase nanostructures of metal organic frameworks (MOF) has recently been considered an effective method for the preparation of synergistic and excellent performance supercapacitor materials. Herein, Ni-Co-Mn-based metal organic frameworks (Ni-Co-Mn MOF) are prepared through an effortless one-step hydrothermal method, in which multiple metal nodes were evenly distributed between MOF nanostructure through ligands and formed a multiphase nanostructure through synergy. The synthesized Ni-Co-Mn0.25 MOF exhibits a prominent specific capacitance of 1575 F g−1 at 1 A g−1, remarkable rate capability and cycling stability. Moreover, we constructed an asymmetrical supercapacitor, which performed an excellent energy density of 73.56 Wh kg−1 at a power density of 399 W kg−1 and great cycling stability with 81.64% of original capacitance after 5000 cycles. Ni-Co-Mn MOF is a promising hybrid electrode material for excellent performance supercapacitor as well as it provides a simple and economic way to fabricate supercapacitor composite materials.
TL;DR: In this article, the synthesis and electrochemical properties of MnO2-based composites with various structures have been discussed in detail, in addition, the development prospect of the composites has been discussed.
Abstract: Manganese dioxide (MnO2) is a promising electrode material for supercapacitors due to its high capacitance, environment friendly, and low cost. However, it shows low specific capacitance and poor circulation in practice because of the disintegration of MnO2 in charge–discharge process. In this review, the synthesis and electrochemical properties of MnO2 and MnO2-based composites with various structures have been discussed in detail. In addition, the development prospect of MnO2-based composites has been discussed.
TL;DR: In this article, the authors summarized the recent progress in the garnet solid electrolytes, the origin of interface resistance between lithium metal and garnet liquid, and the recent development in interfacial engineering for the lithium garnet-based all-solid-state battery.
Abstract: All-solid-state battery is considered as the next generation of the energy storage system because of its improved safety and high-energy density compared to the conventional lithium-ion battery. Among different solid-state battery systems that have been studied, the garnet structured solid electrolyte based solid-state battery has attained tremendous research interest due to the highly advantageous intrinsic property of garnet solid electrolyte, especially high shear modulus, reasonable lithium-ion conductivity, wide electrochemical voltage window, and good stability with electrodes. However, the major hurdle in this battery system is the interfacial issues between lithium metal and lithium garnet solid electrolyte. In this review, we first summarize the recent progress in the garnet solid electrolytes, the origin of interface resistance between lithium metal and garnet solid electrolyte, lithium dendrite propagation in the garnet solid electrolyte, and the recent development in interfacial engineering. Also, we have briefly reviewed the “anode-free” structure for the lithium garnet-based all-solid-state battery and carefully analyzed its importance. We conclude this review with a few suggestions as a guide for future work.
TL;DR: In this paper, a 3D-printed ultra-thick PEDOT-CMC-PEDOT electrode of 1.43 mm thickness at lower rate exhibits a highly improved areal capacity (5.63 mAh cm−2, 0.2 C, 92%).
Abstract: Lithium-ion micro-batteries (LIMBs) with higher energy density have drawn extensive attention. 3D printing technique based on direct ink writing (DIW) is a low-cost and simple approach to fabricate LIMBs especially with higher areal capacity. Herein, poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) nanofibrils are first combined with carbon methyl cellulose (CMC) to achieve the 3D printing of thick LFP (LiFePO4)-PEDOT-CMC electrodes at room temperature by DIW. 3D-printed PEDOT-CMC-based composite thick electrodes demonstrate high conductivity because of the interconnected 3D network including hierarchical macro-micro porous criss-crossing filaments which can provide effective transport paths for Li ions and electrons. Further, LFP-PEDOT-CMC electrodes of different thicknesses are 3D-printed to study the effect of thicknesses on the electrochemical performances. The 3D-printed ultra-thick LFP-CMC-PEDOT electrode of 1.43 mm thickness at lower rate exhibits a highly improved areal capacity (5.63 mAh cm−2, 0.2 C) and high capacity retention (after 100 cycles, 0.2 C, 92%). The rate capability decreases steadily with the increasing thickness. However, for the extra-thick electrodes greater than 1.43 mm thickness, the discharge capacity, rate, and cycle capability decline dramatically. Electrochemical impedance spectroscopy measurements are used to explain the kinetic mechanism. For 3D-printed LFP-CMC-PEDOT electrodes blow 1.43 mm thickness, the 3D network plays the dominant role to maintain the effective transmission dynamics regardless of electrode thickness. But for the extra-thick electrodes, the greater transport distance becomes the major limiting factor resulting in the degradation of electrochemical performances. This work will offer guidance on how to apply 3D-printed ultra-thick electrodes with high energy density to LIMBs.
TL;DR: In this paper, a simple and feasible preparation strategy was applied to fabricate the composite cathode of polyamidoamine (PAMAM) dendritic macromolecule polymer modified the Ketjen Black mixed sublimated sulfur (KAMAM@KB@S).
Abstract: Lithium sulfur (Li-S) batteries were considered the next generation of energy devices with the greatest development potential because of their large theoretical capacity and high energy density. However, many challenges exist in the research field of Li-S batteries, such as low utilization rate of active substances and inferior cycling performance. Here, a simple and feasible preparation strategy was applied to fabricate the composite cathode of polyamidoamine (PAMAM) dendritic macromolecule polymer modified the Ketjen Black mixed sublimated sulfur (PAMAM@KB@S). Benefiting from the improved polysulfides adsorbability due to the abundant functional groups which originate from PAMAM, PAMAM@KB@S composites with 3.94 mg sulfur-loading at a current density of 0.5 C exhibit a high initial specific discharge capacity of 894.3 mAh g−1 and maintain a specific discharge capacity of 455.7 mAh g−1 after 200 cycles. And the average Coulombic efficiency of PAMAM@KB@S electrode (96.7%) within 200 cycles is higher than that of KB@S electrode (88.5%).
TL;DR: In this article, the research progresses of common materials and structures of some supercapacitors are reviewed and related properties and device characterizations of carbon-based, conductive polymer and metal compound electrode materials are introduced.
Abstract: Supercapacitors are a new type of energy storage device between batteries and conventional electrostatic capacitors. Compared with conventional electrostatic capacitors, supercapacitors have outstanding advantages such as high capacity, high power density, high charging/discharging speed, and long cycling life, which make them widely used in many fields such as electronics, aerospace, and vehicles. However, the low energy density of supercapacitors limits their large-scale applications. Therefore, it is of great significance to develop high energy density supercapacitors and use as power sources for practical devices. In order to improve the performance of supercapacitors, the study of materials and structures is very important. In this paper, the research progresses of common materials and structures of some supercapacitors are reviewed. The related properties and device characterizations of carbon-based, conductive polymer and metal compound electrode materials are introduced. The structures of electrode materials, structures of devices, and corresponding properties are discussed.
TL;DR: In this paper, a series of CeO2/MOF/GO composites prepared by the hydrothermal method can be directly used as high-efficiency electrocatalysts.
Abstract: Clean hydrogen energy is urgently needed in the world, so it is necessary to develop a high-efficiency electrocatalyst (OER) for oxygen evolution reaction. Metal–organic frameworks (MOFs) are a class of promising materials for diverse heterogeneous catalysis, but they are usually not directly employed for oxygen evolution electrocatalysis. In this paper, it is reported that a series of CeO2/MOF/GO composites prepared by the hydrothermal method can be directly used as high-efficiency electrocatalysts. The new materials have excellent properties, including high catalytic activity, high specific surface area, and abundant oxygen vacancies. The factors increase the electrochemical surface area (ECSA) and improve the OER performance of the catalyst. The optimized CeO2/MOF/GO catalyst has a low overpotential of 386 mV at 10 mA·cm−2 and a Tafel slope of 98.1 mV·dec−1, and has good stability under alkaline conditions. Therefore, the newly synthesized lanthanide-doped layered materials are expected to be a promising and efficient electrocatalyst for water decomposition.
TL;DR: In this paper, a poly(vinylidene fluoride) (PVDF)-based composite polymer solid electrolyte membrane (CSE) incorporated with Li7La3Zr2O12 (LLZO) fillers and high-strength porous skeleton was prepared.
Abstract: High room-temperature ionic conductivity and mechanical property are essential for the application of solid electrolyte. In this work, a poly(vinylidene fluoride) (PVDF)-based composite polymer solid electrolyte membrane (CSE) incorporated with Li7La3Zr2O12 (LLZO) fillers and high-strength porous skeleton was prepared. The introduction of LLZO increased the ionic conductivity of PVDF at room temperature by reducing the crystallinity of PVDF matrix, and the addition of skeleton greatly improved the mechanical property of electrolyte membrane and inhibited the growth of lithium dendrites. The prepared PVDF-LLZO CSE has a room-temperature ionic conductivity of 1.75 × 10−4 S/cm, and the tensile strength reaches 95 MPa, which greatly enhanced the ability of lithium dendrite suppression. The assembled LiNi0.6Co0.2Mn0.2O2 (NCM622)/CSE/Li cell shows an initial capacity of 151 mAh/g with a retention capacity of 108 mAh/g after 100 cycles at the current density of 0.5 C. This ultrathin PVDF/LLZO CSE has a great application prospect in solid-state lithium batteries.
TL;DR: Li7La3Zr2O12 (LLZO) with high ionic conductivity and excellent chemical and electrochemical stability with metallic Li is considered to be one of the most promising candidates for solid-state batteries as discussed by the authors.
Abstract: Li7La3Zr2O12 (LLZO) with high ionic conductivity and excellent chemical and electrochemical stability with metallic Li is considered to be one of the most promising candidates for solid-state batteries. In this work, Li6.925La3-xYxZr1.925Sb0.075O12 (0 ≤ x ≤ 0.1) garnets were prepared through solid-state reaction method, and effects of the co-dopant on the structure and ionic property are studied. The co-doping of Y3+ (0–0.075) and Sb5+ (0.075) accelerates the formation of cubic phase structure. Meanwhile, Li6.925La2.95Y0.05Zr1.925Sb0.075O12 (relative density ~ 95.1%) showed the highest total conductivity (3.20 × 10−4 S/cm) and the lowest activation energy of 0.30 eV at 30 °C. Moreover, the high discharge capacity and capacity retention of solid-state battery of LiFePO4/Li6.925La2.95Y0.05Zr1.925Sb0.075O12/Li indicate that Y and Sb co-doped Li7La3Zr2O12 ceramic should be a promising electrolyte.
TL;DR: In this article, a yarn-shaped supercapacitor with a ply twist structure was presented, which exhibited excellent electrical conductivity (20 Ω/cm), good mechanical properties (59.8 MPa, 24.6%), a high specific capacitance of 386.5 mF/cm2, and ideal cycle stability with the retention of 87.8% after 5000 cycles.
Abstract: Yarn-shaped supercapacitors are favored due to their small size, high specific capacitance, and light weight. Herein, we reported a distinctive type of ply twist yarn supercapacitor by in situ polymerization of pyrrole on carbon nanotubes (CNTs)/cotton ring spun yarns. CNTs and polypyrrole (PPy) were successfully embedded into the cotton yarns with a ply twist structure. The as-developed electrode exhibited excellent electrical conductivity (20 Ω/cm), good mechanical properties (59.8 MPa, 24.6%), a high specific capacitance of 386.5 mF/cm2 with the current density of 1 mA/cm2, and ideal cycle stability with the retention of 87.8% after 5000 cycles. Meanwhile, the assembled supercapacitor showed a power density of 278.4 μW/cm2 and an energy density of 13.21 μWh/cm2. It also presented outstanding capacitive performance under different angles. This facile ply twist method provided new possibilities for one-dimensional (1D) supercapacitor and flexible wearable electronics applications.
TL;DR: In this article, hexafluoropropylene copolymer (P(VDF-HFP))-based active polymer membranes are prepared by entrapping different extent of pyrrolidinium ionic liquid-based nanofluid (ionanofligid). X-ray diffraction, differential scanning calorimetry (DSC), and Fourier transform infrared (FT-IR) spectroscopy are implemented to characterize the membranes.
Abstract: In the present study, hexafluoropropylene copolymer (P(VDF-HFP))-based “active” polymer membranes are prepared by entrapping different extent of pyrrolidinium ionic liquid-based nanofluid (ionanofluid). X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared (FT-IR) spectroscopy are implemented to characterize the membranes. The study reveals that ionanofluid improves the electroactive phase nucleation of P(VDF-HFP) and suppresses the membranes’ crystallinity. SEM micrographs and butanol absorption study indicate that ionanofluid improves the electrolyte uptake ability and facilitates forming unified ion-conducting channels within the membranes. The 50 wt% ionanofluid (INF) incorporated gel-polymer electrolyte (GPE) exhibits the highest room-temperature ionic conductivity (2.33 × 10−3 S cm−1 at 25 °C), a high lithium-ion transference number (
$$ {t}_{{\mathrm{Li}}^{+}}\sim 0.6 $$
), superior electrochemical stability window up to ~ 5.3 V (vs. Li/Li+) and excellent interfacial compatibility with the lithium electrode. The LiFePO4/Li battery comprising INF-based GPE demonstrates good C-rate performance and excellent cycling stability with a discharge capacity of ~ 156 mAh g−1 and ~ 116 mAh g−1 at C/5 and 2 C rates, respectively, and capacity retention of > 95% after 50 cycles at C/5 rate.
TL;DR: In this article, a facile method is reported for the synthesis of ZIF-67-derived cobalt and nitrogen-doped carbon (Co-N-C) materials with enlarged average pore sizes as electrocatalysts towards oxygen reduction reaction (ORR).
Abstract: In this work, a facile method is reported for the synthesis of ZIF-67-derived cobalt and nitrogen-doped carbon (Co-N-C) materials with enlarged average pore sizes as electrocatalysts towards oxygen reduction reaction (ORR). The pore diameters of the Co-N-C can be greatly enlarged using NaCl as an additive during the pyrolyzing process. Thermo-gravimetry (TG) results suggest that NaCl could facilitate the structural decomposition of ZIF-67, resulting in the adjusted physiochemical properties of the obtained Co-N-C materials. The CoNC-1NaCl-700 and CoNC-1NaCl-800 materials derived from ZIF-67 in the presence of NaCl at relatively high pyrolyzing temperatures (i.e., 700 °C, 800 °C) exhibit superior catalytic activity compared with the CoNC materials derived from pure ZIF-67, which could be due to their unique structures of larger average pore sizes, higher surface areas, higher contents of pyridinic-N and graphitic-N. The onset potential of the CoNC-1NaCl-800 towards ORR is 0.94 V (vs. RHE) and the half-wave potential is 0.84 V (vs. RHE), which are comparable with that of commercial Pt/C.
TL;DR: In this article, a series of MXene/Pt-x nanomaterials were fabricated via a facile synthesis method, in which coral-like Pt nanoparticles (NPs) were deposited on Ti3C2Tx MXene.
Abstract: Exploring efficient catalysts for hydrogen evolution reaction (HER) is one of focus points of energy research. In this work, a series of MXene/Pt-x (wherein, x is the adding amount of 6.2 mM H2PtCl6 solution) nanomaterials were fabricated via a facile synthesis method, in which coral-like Pt nanoparticles (NPs) were deposited on Ti3C2Tx MXene. The Pt-loading amounts on the MXene could be simply controlled by varying the adding amounts of H2PtCl6, which would influence the sizes of Pt NPs on the MXene. The optimum catalytic activity was obtained on the MXene/Pt-3 with a low overpotential of 302 mV versus reversible hydrogen electrode (RHE) at 10 mA cm−2, which was about 84 mV less than MXene/Pt-2. The efficiently electrocatalytic HER activity of MXene/Pt-x nanomaterials was due to the electron transfer from MXene to Pt NPs. The HER performance of the MXene/Pt-x nanomaterials was influenced by both Pt-loading amounts and Pt particle sizes. This work expands future applications of MXene-based nanomaterials in clean energy conversion reactions.
TL;DR: In this paper, the influence of water content on the lithium storage performance of α-Ni(OH)2 samples prepared by homogeneous precipitation method and subsequent heat treatment at different temperatures was investigated.
Abstract: In this work, we investigate the influence of water content on the lithium storage performance of α-Ni(OH)2 samples prepared by homogeneous precipitation method and subsequent heat treatment at different temperatures. It is found that the adsorbed water in α-Ni(OH)2 has a decisive impact on the cycling stability and rate capability of the electrode; in contrast, the effect of interlayer water contents is not significant. For example, the α-Ni(OH)2 sample with adsorbed water molecules (heat-treated at 100 °C) delivers a reversible specific capacity of 1115 mAh g−1 at 500 mA g−1 after 30 cycles, while the α-Ni(OH)2 sample after removing the adsorbed molecules (heat-treated at 150 °C) gives a capacity of only 516 mAh g−1 under the same measurement condition. EIS and CV analyses reveal that the adsorbed water molecules in α-Ni(OH)2 decrease the electrochemical reaction resistance, increase lithium ion diffusivity, and greatly enhance the pseudocapacitive charge storage behavior, which lead to superior performance in cycle life and rate capability.
TL;DR: In this paper, the Co3O4@rGO derived from metal-organic frameworks (MOFs) were prepared by a simple solvothermal method followed by the heat treatment.
Abstract: The Co3O4@rGO derived from metal–organic frameworks (MOFs) were prepared by a simple solvothermal method followed by the heat treatment. In a typical preparation process, the Co-MOF (ZIF-67) acts as the precursor to obtain desirable nano Co3O4 while the reduced graphene oxide (rGO) layer enhances the conductivity. The materials were respectively characterized by XRD, SEM, and then further electrochemical tests. As anode materials for lithium-ion batteries (LIBs), the material of Co3O4@rGO exhibit overall superb electrochemical properties especially when the rGO proportion is 20%, it displays higher capacity (818.5 mAh g−1 at 100 mA g−1), higher cycling stability (87.3% capacity retention after 100 cycles), and better rate performance. The work may throw some lights on the preparation of other transition metal oxides by structure design with rGO layer for further applications.
TL;DR: LiFePO3.98F0.02/3DG/C material was synthesized by using a two-step carbothermal reduction technology with ascorbic acid and glucose as carbon sources.
Abstract: Regular spherical FePO4/3DG precursor with good dispersion, uniform morphology, and diameters of 2~3 μm was hydrothermally synthesized, followed by synthesizing LiFePO3.98F0.02/3DG/C material via a two-step carbothermal reduction technology with ascorbic acid and glucose as carbon sources. The morphology, structure, and carbon content of the material were characterized by SEM, XRD, XPS, TEM, and thermogravimetric analyzer (TGA). The electrochemical properties of material were systematically studied by means of constant current charge and discharge, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). The results revealed that the initial discharge specific capacity of LiFePO0.98F0.02/3DG/C material was 158.7, 144.5, 130.4, 114.8, 96.8, and 80.3 mAh/g at 0.2 C, 0.5 C, 1 C, 2 C, 5 C, and 10 C, respectively, and the capacity retention rate still remained 98.9% after 100 cycles at 0.2 C, indicating excellent rate performance and cycle stability. Obviously, LiFePO3.98F0.02/3DG/C material exhibited remarkable improvement in comparison with the pristine LiFePO4 material. Therefore, the synergy of F− doping and 3DG coating was an effective method in synthesis of high electrochemical performance LiFePO4 composite material.
TL;DR: In this paper, the authors demonstrate urchin-like molybdenum disulfide (MoS2) with conducting polyaniline (PANI) as hybrid electrode materials via one-pot hydrothermal method.
Abstract: Conducting polyaniline (PANI) has been widely considered as a promising energy storage material with excellent electrochemical reversibility and high theoretical specific capacitance. Suffering from poor cyclic stability of PANI, here we demonstrate urchin-like molybdenum disulfide (MoS2) with PANI as hybrid electrode materials (MoS2@PANI) via one-pot hydrothermal method. In our case, the electrostatic attraction and hydrogen bond interaction between MoS2 and PANI synergically improve the structural integrity and specific surface area of the binary MoS2@PANI hybrids. Specifically, MoS2@PANI with 25 wt% MoS2 (PM25) delivers a maximum capacitance of 645 F g−1 at 0.5 A g−1 with good cycling stability (89% capacitance retention after 2000 cycles at a current density of 10 A g−1). Compared to pure PANI (335 F g−1), the improvement of capacitive energy storage ability indicates that urchin-like MoS2@PANI hybrids with a stable morphology and unique structure are promising for hybrid supercapacitor materials.
TL;DR: In this paper, ammonium bromide (NH4Br)-salt was added to higher conducting polymer electrolytes to reveal the appearance of complex formation between the polymer and salt.
Abstract: Proton conducting polymer blend electrolytes based on cornstarch and polyvinyl pyrrolidone (PVP) with ammonium bromide (NH4Br) were prepared by the technique of solution casting. Enhancement of amorphous nature by the addition of NH4Br has confirmed by XRD. In FTIR,by the addition of NH4Br salt in the optimized blend system, there occurs a change like altering the peak intensity, peak shape, and position. This reveals the appearance of complex formation between the polymer and salt. At 358 K, 30 wt.% of NH4Br added system shows the maximum conductivity (1.31 × 10−4 S cm−1). The conduction mechanism of higher conducting polymer blend electrolytes follows the quantum mechanical tunneling (QMT) at mid-frequency and overlapping large polaron tunneling (OLPT) at higher frequency. High dielectric constant and low relaxation time of ions in polymer chain are obtained for 30 wt.% of NH4Br added polymer blend electrolyte. From Wagner’s polarization technique, it is established that conduction present in the polymer electrolytes is predominately due to ions. Faradaic pseudo capacity behaviour has observed in higher conducting sample by cyclic voltammetry. The electrochemical cell has prepared by the higher conducting polymer electrolyte and the open circuit potential (OCP) of 1.24 V has achieved from prepared electrochemical cell.
TL;DR: In this paper, a nanosheet-based catalysts for hydrogen evolution reaction and oxygen evolution reaction (OER) was proposed. And the performance of the Mo-CoP was investigated in terms of current density of 100 mA/cm2 for HER and OER in 1.54 V.
Abstract: Transition-metal doping and structural improvement are facile and feasible strategies to obtain highly active catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Herein, we prepare Mo-CoP with a nanosheet structure via hydrothermal reactions and phosphorization. Taking advantage of the nanosheet array, the good electrocatalytic performance of Co-based materials for HER and excellent performance of Co-based phosphide for OER are fully demonstrated. Mo-CoP requires only 112 and 329.9 mV to achieve a current density of 100 mA/cm2 for HER and OER in 1.0 M KOH, respectively. Furthermore, when it was used as bifunctional electrocatalyst, Mo-CoP could deliver 10 mA/cm2 at a low cell voltage of 1.54 V. It was found that the activity of Mo-CoP could be ascribed to the structure of nanosheet and the synergistic role of two different metal phosphides. The most important is that the introduction of Mo improves the activity of the catalyst.