Applications In Electrochemical Devices Research Articles

Delocalized Polarons in Diketopyrrolopyrrole‐Based Conjugated Polymers: Implications for Near‐Infrared Electrochromism and Beyond

AbstractConjugated polymers with delocalized polarons and near‐infrared (IR) absorption properties are promising materials for applications in electrochemical devices. However, the poor stability of low bandgap polymers in electrochemical redox conditions limits the realization of such devices. Herein, a new family of near‐IR absorbing conjugated polymers based on diketopyrrolopyrrole (DPP) derivatives with methoxy substituents to achieve reversible p‐type electrochemical doping with bistable near‐IR electrochromism is designed. The extent of volumetric doping in various electrolytes using cyclic voltammetry and spectroelectrochemistry for optimal electrochemical kinetics and near‐IR contrast is systematically investigated. Further, the spray‐coated films of polymers display high open circuit memory as the methoxylation is increased on the polymer backbone. The contrasting electrochromic memory and kinetics observed for these polymers are mainly ascribed to two factors; i) the effect of backbone structure on the spatial extent of polaron delocalization, and ii) the ionization energy of the polymers. The utility of DPP‐based polymers as energy‐efficient electrochromic optical attenuators (EVOAs) with high near‐IR coloration efficiencies, and an optical attenuation value of 5.1 dB at 1.3 and 1.5 µm wavelengths is demonstrated. Furthermore, the experimental findings are corroborated with theoretical studies to establish that the polaron delocalization length is central to the performance of the device.

A Review of Perovskite-based Lithium-Ion Battery Materials

Lithium-ion batteries (Li-ion batteries or LIBs) have garnered significant interest as a promising technology in the energy industry and electronic devices for the past few decades owing to their superior energy and power density profiles, small size, long cycle life, low self-discharge rate, no memory effect, long-lasting power properties, and environmental friendly. The ongoing advancement of electrode and electrolyte materials has contributed significantly to enhancing and spreading the application of lithium-ion battery technology. Among the non-precious metal-based materials, perovskites have emerged as attention over the last decade, holding a prominent position in materials and energy. Due to their unique physical and chemical properties, these materials have garnered particular interest for their potential application in electrochemical energy devices. Perovskite oxides have piqued the interest of researchers as potential catalysts in Li-O₂ batteries due to their remarkable electrochemical stability, high electronic and ionic conductivity, and the ability to modify their properties through doping and element substitution. The purpose of this article is to provide an overview of recent developments in the application of perovskites as lithium-ion battery materials, including the exploration of novel compositions and structures, optimization of fabrication methods, and a deeper understanding of the fundamental mechanisms that can unveil the potential of perovskite materials.

Electrochemical properties of plasticized PVA-based electrolyte inserted with alumina nanoparticles for EDLC application with enhanced dielectric constant

In the current study, the role of alumina nanoparticles was examined in the electrochemical and device performance of PVA-based electrolytes. The NaSCN was used as a cation provider for the host electrolyte, and the glycerol plasticizers were used to enhance conductivity and flexibility. The ratio of salt and plasticizer was fixed, while nanoparticles were varied. The results of impedance AC conductivity confirm that 3 wt% of alumina insertion results in high DC conductivity, which is sufficient for electrochemical device application. Electrode polarization region and plateau area are clearly distinguished in AC spectra. The study of the Dielectric constant reveals that charge storage is maximum at 3 wt% of alumina. The dielectric constant values are about twice the dielectric loss value, which is the topic of immense scientific discussion. The contribution of ion fraction was found to be 0.94, which is excellent compared to the negligible contribution of electrons, which is about 0.05. Electrochemical stability is an additional crucial factor and was found to be 2.47 V. To identify any Redox or non-Redox phenomena occurring in the electrical double-layer capacitor (EDLC) cyclic voltammetry (CV) as the simplest analysis method has been carried out on the sample having the highest DC value. A leaf-like form of the CV plot was noticed at high scan rates, while a rectangular shape was identified at low scan rates. The charge-discharge shape is almost close to the ideal triangular pattern. The discharge part was used to calculate critical EDLC device parameters such as ESR, efficiency, specific capacitance power density, and energy density over 2000 cycles. Low ESR (below 60 Ω) and stable efficiency (almost 100 %) of the device results in high capacitance (≈87 F/g), power density (2978 Wh/kg), and energy density (12.86 W kg−1). The results established that nan-fillers alongside plasticizer is crucial to deliver EDLC devices with improved performances.

Boosting supercapacitive performance of SnS2 via trace Pb doping

High-performance electrode materials are crucial for enhancing the performance of supercapacitors. Among various candidates, pseudo-capacitive SnS2 is a promising one due to its high specific capacitance, earth-abundance, nontoxicity as well as low-cost. However, its actual electrochemical performance is restricted owing to the poor intrinsic conductivity and current fabrication processes on improving the conductivity are usually complicated. In this study, based on first-principles calculations, Pb doping is introduced to enhance the conductivity of SnS2. Pb-doped SnS2 nanosheets are synthesized via a simple one-step hydrothermal method. With trace Pb doping (Pbo.o1SnS2), an impressive 4-order-of-magnitude increase in conductivity was achieved compared to pristine SnS2. Furthermore, Pb-doped SnS2 nanosheets exhibit a superior mass-specific capacitance of 533.7 F g−1 at 50 mV s−1 and excellent long-term capacitance retention of 90.2 % over 100,000 cycles at 5 A g−1. This study presents a simple and effective approach to enhancing the supercapacitor performance of SnS2 and advances the practical applications of electrochemical energy storage devices based on 2D materials.

Ion Conduction Mechanism in Polymer Blend Electrolyte Films

AbstractThis paper presents the development of the blend polymer solid electrolyte films (BPSE) for potential applications in electrochemical devices. Two host polymers, polyvinyl alcohol (PVA) and polymethyl methacrylate (PMMA), along with the salt KI, are employed to create the solid polymer electrolytes (SPEs). The synthesis involves varying the weight percentage of salt within the SPEs to investigate its impact on the material properties. Conductivity measurements are conducted using AC impedance spectroscopy, unveiling the conductivity behavior of the BPSEs. Additionally, surface morphology is characterized using polarized optical microscopy (POM) at 10 pixel resolution, offering a detailed examination of the film's microstructure. This comprehensive study not only contributes to the understanding of the fundamental properties of BPSEs but also opens avenues for their utilization in various electrochemical applications.

Thermophysical and transport properties of a pyrrolidinium-based ionic liquid confined in silica

Ionic liquid (IL) 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMPyrrTFSI) was confined in silica (Aerosil A380) by direct mixing. The resulting BMPyrrTFSI/xSiO2 ionogel (x – from 2.3 to 6.7 wt%) was studied by TG, DSC, conductometry and viscometric methods. For confined IL, a decrease in the Tm and Ts-s by 14–16 °C and an increase in the Tg, and Tcc by 4–5 °C were found. With an increase in xSiO2, the opposite dynamics of the decomposition temperatures Tonset and Tpeak, and a disproportionate decrease in ionic conductivity were observed. The change in the properties of BMPyrrTFSI under conditions of limited geometry of the silica matrix is explained in the terms by the interaction of the IL and SiO2, as well as the conformation features of the cation and anion. In the first time, parameters such as the fragility index D and the formation factor F were also discussed for such systems. As a result, BMPyrrTFSI/4.5 wt% SiO2 ionogel (0.2 S m−1, 20 °C) was proposed as a promising electrolyte for application in electrochemical devices. This study may be useful for creating quasi-solid electrolytes based on ILs and inorganic materials.

Preparation of eco-friendly biopolymer electrolyte, K-carrageenan with zinc nitrate hexahydrate salt, for application in electrochemical devices

Preparation of eco-friendly biopolymer electrolyte, K-carrageenan with zinc nitrate hexahydrate salt, for application in electrochemical devices

A Bi2Te3 topological insulator/carbon nanotubes hybrid composites as a new counter electrode material for DSSC and NIR photodetector application

Two-dimensional layered bismuth telluride (Bi2Te3), a prominent topological insulator, has garnered global scientific attention for its unique properties and potential applications in optoelectronics and electrochemical devices. Notably, there is a growing emphasis on improving photon-to-electron conversion efficiency in dye-sensitized solar cells (DSSCs), prompting the exploration of alternatives to noble metal catalysts like platinum (Pt). This study presents the synthesis of Bi2Te3 and its hybrid nanostructure with single-wall carbon nanotubes (SWCNT) via a straightforward hydrothermal process. The research unveils a novel application for the Bi2Te3-SWCNT hybrid structure, serving as a counter electrode in platinum-free DSSCs, facilitating the conversion of triiodide (I3−) to iodide (I−) and functioning as an active electrode material in a photodetector (n-Bi2Te3-SWCNT/p-Si). The resulting DSSC employing the Bi2Te3-SWCNT hybrid counter electrode achieves a power conversion efficiency (PCE) of 4.2 %, a photocurrent density of 10.5 mA/cm2, a fill factor (FF) of 62 %, and superior charge transfer kinetics compared to pristine Bi2Te3 based counter electrode (PCE 2.1 %, FF 34 %). Additionally, a spin coating technique enhances the performance of the n-Bi2Te3-SWCNT/p-Si photodetector, yielding a responsivity of 2.2 AW−1, detectivity of 1.2 × 10−3 and enhanced external quantum efficiency. These findings demonstrate that the newly developed Bi2Te3-SWCNT heterostructure enhances interfacial charge transport, electrocatalytic performance in DSSCs, and overall photodetector performance.

Microwave Synthesis of New Co-Polypyrrole-Polyketone Anion Exchange Membranes

Polyketones can be easily converted in a series of new polymeric anion exchange membranes (AEMs) with a stable polypyrrole-polyketone backbone structure from which the ion exchange side-groups stem [1-3]. Here we present our findings on the functionalization with two different cycloaliphatic primary amines of a commercial and inexpensive terpolymer polyketone (PK) through the Paal-Knorr chemistry. We also studied the possibility to drastically reduce the reaction time by investigating alternative and greener heating sources such as microwave heating. The molecular structure, thermal and conductive properties of the membranes were studied in order to shed light on and compare the effect of the different heating methods on the materials behavior [4], and to lead the way to their further optimization for the possible application in electrochemical devices. The obtained membranes showed a promising anion conductivity in the hydroxide form, up to 10mScm-1, and an exceptional thermal stability, about 250°C.[1] G.Nawn, K.Vezzù, G.Cavinato, G.Pace, F.Bertasi, G.Pagot, E.Negro, V. Di Noto, Adv. Funct. Mater. 2018, 1706522[2] N.Ataollahi, F.Girardi, E.Cappelletto, K.Vezzù, V.Di Noto, P.Scardi, E.Callone, R.Di Maggio. Journal of Applied Polymer Science. 2017, 134, 45485.[3] A.R.Alvi, K.Vezzù, , G.Pagot, P.Sgarbossa, G.Pace, V.Di Noto, Macromolecular Chemistry & Physics. 2022, 223, 2100409.[4] S.Bonizzoni, D.Stucchi, T.Caielli, E.Sediva, M.Mauri, P.Mustarelli, ChemElectroChem. 2023, e202201077. Figure 1

Boosted electrocatalytic activity and durability of Cu[sbnd]Fe/N[sbnd]C by modulating the interfacial composition and electronic structure for efficient oxygen reduction reaction

Oxygen reduction reaction (ORR) serves as the foundation for various electrochemical energy storage devices. Fe/NC catalysts are expected to replace commercial Pt/C as oxygen electrode catalysts based on the structural tunability at the atomic level, abundant iron ore reserves and excellent activity. Nevertheless, the lack of durability and low active site density impede its advancement. In this work, a durable catalyst, CuFe/NC, for ORR was prepared by modulating the interfacial composition and electronic structure. The introduction of Cu nanoclusters partially eliminates the Fenton effect from Fe and optimizes the electron structure of FeNx, thereby effectively enhancing the long-term durability and activity. The prepared CuFe/NC exhibits a half-wave potential (E1/2) of 0.90 V and superior stability with a decrease in E1/2 of only 20 mV after 10,000 cycles. The assembled alkaline Zinc-Air batteries (ZABs) with CuFe/NC exhibit an open-circuit potential of 1.458 V. At a current density of 5 mA cm−2, the batteries are capable of operation for 600 h with a stable polarization. This CuFe/NC may promote the practical application of novel and renewable electrochemical energy storage devices.

The effect of silicon dioxide on the structural, thermal and transport properties of an organic ionic plastic crystal (n-C4H9)4NBF4

Composite solid electrolytes based on an organic ionic plastic crystal (n-C4H9)4NBF4 with highly dispersed SiO2 with specific surface area of Ss = 324±10 m2/g have been studied for the first time. By methods of X-ray diffraction and differential scanning calorimetry, it was found that the introduction of SiO2 leads to amorphization of the salt. An unusual size effect was observed in the composites: the temperature of the polymorphic transition of the salt shifted from 67 °C to 60 °C, while the melting point did not change. The 0.15(n-C4H9)4NBF4–0.85SiO2 composite was found to possess the highest electrical conductivity (σ = 2∙10–5 S/cm at 150 °C), which is 1.5 orders of magnitude higher than that of the initial salt. Modelling of the concentration dependences of the electrical conductivity of composites using the mixing equation showed that the reason for the increase in electrical conductivity is the formation of an amorphous layer of salt, the electrical conductivity of which is 3 orders of magnitude higher than that of the crystalline phase (n-C4H9)4NBF4. The obtained results can be used for the design of high-performance composites based on organic ionic plastic crystals for application in electrochemical devices.

Harnessing halides: Comparative study of oxide fullerene modifications for sodium ion secondary battery efficiency

The quest for secondary batteries drives ongoing research aimed at developing cost-effective and high-performance nanomaterials. While lithium-ion batteries initially offered high efficiency, however escalating demand has led to increased costs prompting exploration of other alternatives such as sodium (Na) ion batteries. Na resources are much more abundant and widely distributed globally compared to lithium. This study explores the potential of sodium ion battery by adopting a novel approach of incorporating endohedral halides into oxides fullerenes to enhance the voltage. We investigated the thermodynamic and electronic stabilities of Na/Na+ ions with both bare and halide-doped magnesium oxides (Mg12O12) and zinc oxides (Zn12O12) fullerenes to understand how encapsulated halide affects the structural and electrochemical properties. The bare oxide fullerenes exhibit cell voltages of 0.29 and −0.50 V in the presence of toluene solvent. Upon incorporation of various halide ions into oxides fullerenes, we obtained cell voltage in acceptable range for anode materials. Specifically, the variation in free energy experiences a remarkable improvement where the Cl−@Zn12O12 in toluene has the most appropriate cell voltage of 1.09 V in the presence of toluene solvent, among all halides adsorbed oxides nanocages. These findings provide valuable insights for the design of novel low-cost nanomaterials having better cell voltage. The endeavor additionally catalyzes further research work into the design of halide-encapsulated oxide-fullerene-based secondary batteries, intended for widespread applications in electrochemical energy storage devices. This comprehensive work serves as a detailed blueprint for experimentalists, facilitating the synthesis of such systems to address the future challenges posed by energy scarcity.

Recent Progress in the Applications of Langmuir-Blodgett Film Technology.

Langmuir-Blodgett (LB) film technology is an advanced technique for the preparation of ordered molecular ultra-thin films at the molecular level, which transfers a single layer of film from the air/water interface to a solid substrate for the controlled assembly of molecules. LB technology has continually evolved over the past century, revealing its potential applications across diverse fields. In this study, the latest research progress of LB film technology is reviewed, with emphasis on its latest applications in gas sensors, electrochemical devices, and bionic films. Additionally, this review evaluates the strengths and weaknesses of LB technology in the application processes and discusses the promising prospects for future application of LB technology.

Electrochemical study of cerium and iron doped MoO3 nanoparticles showing potential for supercapacitor application

This study presents the synthesis and comprehensive characterization of undoped MoO3 and its cerium (Ce) and iron (Fe) doped counterparts via hydrothermal route, with a 5 % doping concentration. Structural analysis by X-ray diffraction confirmed the formation of MoO3 with successful doping. UV–vis spectroscopy demonstrated tunable optical properties, with band gap energies of 2.3 eV, 2.0 eV, and 2.8 eV for undoped, Ce-doped and Fe-doped MoO3 respectively. Morphological investigation using scanning electron microscopy revealed distinct nanostructures, including nanorods, agglomerated nanoparticles, and pebble-like structures, influenced by doping. Electrochemical characterization through cyclic voltammetry and potentio electrochemical impedance spectroscopy showcased superior charge storage capacity in Fe-doped MoO3, attributed to the largest area under the curve in cyclic voltammograms. Fe-doped MoO3 exhibited lowest resistance as compared to undoped and Ce doped MoO3, suggesting enhanced conductivity. The presence of a Warburg element in all samples indicated diffusion-limited electrochemical processes. The variation of log (scan rate) with log (current) revealed distinct charge transfer mechanisms, with near-unity slopes for doped samples and a slope near 0.5 for undoped MoO3. These findings provide insights into the tunable properties of doped MoO3, offering potential applications in various electrochemical devices.

Development of low-viscosity phosphonium-based ionic liquid electrolytes for lithium-ion batteries: Charge–discharge performance and ionic transport properties

Phosphonium cation-based ionic liquids (phosphonium ILs) have several advantages for electrochemical device applications compared with ammonium cation-based ionic liquids because of their unique features, such as higher ionic conductivity and a larger electrochemical potential window. In this study, we prepared various phosphonium ILs with different substituents (alkyl, alkyl ether, or allyl) on the cation, and bis(fluorosulfonyl)amide (FSA) or bis(trifluoromethanesulfonyl)amide (TFSA) as the anion. This study describes these phosphonium ILs used as electrolytes for lithium-ion batteries and investigates their performance as typical Li/LiCoO2 cells. We demonstrate that discharge capacity increases with increasing lithium-ion conductivity determined by electrochemical impedance and pulsed-field gradient nuclear magnetic resonance. A discharging rate test conducted in constant current (CC) mode also displays good high conductivity phosphonium IL electrolyte performance. Furthermore, the difference in cycle performance between FSA-based and TFSA-based phosphonium IL electrolytes is explained in terms of solid electrolyte interphase formation, similar to the performance of other cation-based ILs.

Challenges faced with 3D-printed electrochemical sensors in analytical applications.

Prototyping analytical devices with three-dimensional (3D) printing techniques is becoming common in research laboratories. The attractiveness is associated with printers' price reduction and the possibility of creating customized objects that could form complete analytical systems. Even though 3D printing enables the rapid fabrication of electrochemical sensors, its wider adoption by research laboratories is hindered by the lack of reference material and the high "entry barrier" to the field, manifested by the need to learn how to use 3D design software and operate the printers. This review article provides insights into fused deposition modeling 3D printing, discussing key challenges in producing electrochemical sensors using currently available extrusion tools, which include desktop 3D printers and 3D printing pens. Further, we discuss the electrode processing steps, including designing, printing conditions, and post-treatment steps. Finally, this work shed some light on the current applications of such electrochemical devices that can be a reference material for new research involving 3D printing.

Harmonizing Energies: The Interplay Between a Nonplanar SalEn-Type Molecule and a TEMPO Moiety in a New Hybrid Energy-Storing Redox-Conducting Polymer.

Redox-conducting polymers based on SalEn-type complexes have attracted considerable attention due to their potential applications in electrochemical devices. However, their charge transfer mechanisms, physical and electrochemical properties remain unclear, hindering their rational design and optimization. This study aims to establish the influence of monomer geometry on the polymer's properties by investigating the properties of novel nonplanar SalEn-type complexes, poly[N,N'-bis(salicylidene)propylene-2-(hydroxy)diaminonickel(II)], and its analog with 2,2,6,6-tetramethylpiperidinyl-N-oxyl (TEMPO)-substituted bridge (MTS). To elucidate the charge transfer mechanism, operando UV-Vis spectroelectrochemical analysis, electrochemical impedance spectroscopy, and electron paramagnetic resonance are employed. Introducing TEMPO into the bridge moiety enhanced the specific capacity of the poly(MTS) material to 95mA h g-1, attributed to TEMPO's and conductive backbone's charge storage capabilities. Replacement of the ethylenediimino-bridge with a 1,3-propylenediimino- bridge induced significant changes in the complex geometry and material's morphology, electrochemical, and spectral properties. At nearly the same potential, polaron and bipolaron particles emerged, suggesting intriguing features at the overlap point of the electroactivity potentials ranges of polaron-bipolaron and TEMPO, such as a disruption in the connection between TEMPO and the conjugation chain or intramolecular charge transfer. These results offer valuable insights for optimizing strategies to create organic materials with tailored properties for use in catalysis and battery applications.

Tailored Synthesis of CN-PPy Composite for Enhanced Electrochemical Functionality

This study details the synthesis of pure carbon nitride (CN) and composite polypyrrole through an in-situ polymerization method. The prepared samples were comprehensively characterized using Fourier Transform Infrared Spectroscopy (FT-IR), Field Emission Scanning Electron Microscopy (FESEM), and X-ray Diffraction (XRD). These analyses confirmed the chemical bonding, structural, and morphological characteristics of the products. Electrochemical measurements, conducted through cyclic voltammetry (CV) and Linear Sweep Voltammetry (LSV), revealed significant current rates in both anodic and cathodic peaks, indicating superior electrochemical properties. This work not only details the synthesis process but also provides a thorough understanding of the structural, morphological, and electrochemical aspects, exhibiting the materials’ potential for various applications in electrochemical devices.

Selenium‐Based Catalysts for Efficient Electrocatalysis

AbstractElectrocatalytic technology is essential to develop environmentally friendly energy technologies and to reduce dependence on non‐renewable resources. The construction of highly efficient, inexpensive, and robust electrocatalysts is the primary prerequisite to the large‐scale application of electrochemical devices. In recent years, selenium‐based catalysts (SBCs) have been extensively investigated and emerged as a promising candidate for electrocatalysis given their potential to reduce or replace the dosage of noble metals and their ability to catalyze a range of critical electrochemical processes. This Review minutely analyses the recent research advances in SBCs, highlighting the significant role of Se in enhancing the catalytic performance. First, it starts from the concepts related to SBCs, followed by the classification of SBCs as well as the strategies to regulate the activity of SBCs are elaborated. Then, the techniques for characterizing SBCs are systematically summed up, mainly focusing on morphological and structural characterization methods. Next, the applications of SBCs in various energy‐conversion reactions (e.g., hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, nitrogen reduction reaction, CO2 reduction reaction) are discussed, aiming at elucidating the association between their structure–activity correlations. Finally, the challenges related to SBCs and their future development trends are presented.

A novel protonic ceramic fuel cell with SrSn0.8Sc0.2O3-δ electrolyte

The recent discovery of SrSn0.8Sc0.2O3-δ (SSS) perovskite oxide as a promising proton-conducting material has generated interest in its potential application in electrochemical devices as PCFCs. This study assesses the feasibility of SSS in PCFCs by its stability, density, chemical compatibility, and electrochemical performance. The study demonstrated the favorable stability of SSS even after reduction at 800 °C under H2 for 24 h as well as immersion in boiling water for 5 h. The relative density of SSS could easily exceed 94% after sintering with NiO aid at 1400 °C. The chemical compatibility and electrochemical performance of SSS were investigated with various electrode materials. The BaCo0.4Fe0.4Zr0.1Y0.1O3-δ exhibited relatively better electrochemical performance with SSS. The electrolyte was co-sintered with a Ni-based anode substrate and densified to high density at 1450 °C without sintering aids. The fuel cell utilizing an anode-supported Ni-SSS|SSS|BCFZY-SSS configuration exhibited a peak power density of 432.1 mW cm−2 at 800 °C.