Applications In Electrochemical Devices Research Articles

Proton and Oxygen-Ion Conductivities of Hexagonal Perovskite Ba5In2Al2ZrO13.

The hexagonal perovskite Ba5In2Al2ZrO13 and In3+-doped phase Ba5In2.1Al2Zr0.9O12.95 were prepared by the solid-state synthesis method. The introduction of indium in the Zr-sublattice was accompanied by an increase in the unit cell parameters: a = 5.967 Å, c = 24.006 Å vs. a = 5.970 Å, c = 24.011 Å for doped phase (space group of P63/mmc). Both phases were capable of incorporating water from the gas phase. The ability of water incorporation was due to the presence of oxygen deficient blocks in the structure, and due to the introduction of oxygen vacancies during doping. According to thermogravimetric (TG) measurements the compositions of the hydrated samples corresponded to Ba5In2Al2ZrO12.7(OH)0.6 and Ba5In2.1Al2Zr0.9O12.54(OH)0.82. The presence of different types of OH−-groups in the structure, which participate in different hydrogen bonds, was confirmed by infrared (IR) investigations. The measurements of bulk conductivity by the impedance spectroscopy method showed that In3+-doping led to an increase in conductivity by 0.5 order of magnitude in wet air (pH2O = 1.92·10−2 atm); in this case, the activation energies decreased from 0.27 to 0.19 eV. The conductivity−pO2 measurements showed that both the phases were dominant proton conductors at T < 500 °C in wet conditions. The composition Ba5In2.1Al2Zr0.9O12.95 exhibited a proton conductivity ~10−4 S·cm−1 at 500 °C. The analysis of partial (O2−, H+, h•) conductivities of the investigated phases has been carried out. Both phases in dry air (pH2O = 3.5·10−5 atm) showed a mixed (oxygen-ion and hole) type of conductivity. The obtained results indicated that the investigated phases of Ba5In2Al2ZrO13 and Ba5In2.1Al2Zr0.9O12.95 might be promising proton-conducting oxides in the future applications in electrochemical devices, such as solid oxide fuel cells. Further modification of the composition and search for the optimal dopant concentrations can improve the H+-conductivity.

Electrical Characteristics of Metal Contacts to Carbon Nanowalls

The electrical characteristics of metal contacts to vertically-aligned nanographite structures, the so-called carbon nanowalls (CNWs), are examined using nickel as the electrode material. The total resistance between a pair of electrodes on CNWs is regarded as the sum of the serial resistance of CNWs and two metal-CNWs contacts to measure the contact resistance and specific contact resistivity by the transmission line method and transfer line method, respectively. The contact resistance and resistivity are around 2.8 Ω and 0.1 Ω cm2, respectively, at room temperature and decrease gently to 2.4 Ω and 0.06 Ω cm2, respectively, when the temperature is increased up to 300 °C. The apparent activation energy corresponding to the conduction barrier at the contact is in the range of 10−3 eV to 10−2 eV, which is comparable with that for the sheet resistance of CNWs. The contact resistance occupies a large portion of the total resistance between a pair of electrodes even at high temperatures, thus affecting electrical signal measurement in electronic and electrochemical device applications.

Isomeric effects of poly-viologens on electrochromic performance and applications in low-power electrochemical devices

Electrochromic (EC) behaviors of poly-viologens are tuned by selecting positions ( ortho ( o ) , meta ( m ), and para ( p )) of the benzene rings linked to 4,4′-bipyridine. All-in-one type EC devices (ECDs) are conveniently fabricated by adding poly-viologens to highly conductive solid-state polymeric gel electrolytes. The maximum transmittance contrast (Δ T ) of the o -poly-viologen based ECD is much lower than that of the other isomers, and its bleaching is not reversible, whereas a large Δ T and high stability are achieved with the m - and p -poly-viologens. Considering the high solubility of the m -poly-viologen in ion gels, it is anticipated to have a larger hydrodynamic size, leading to low diffusivity (∼1.1 × 10 −12 cm 2 /s for cationic and ∼2.7 × 10 −12 cm 2 /s for anionic current). As a result, the m -poly-viologen ECD shows a superior memory effect and long-lasting colored state without voltage supply. This feature allows us to demonstrate a low-power ECD based on the m -poly-viologen, which only requires ∼3.54 μW/cm 2 to maintain the transmittance below 30%. The results indicate that adjusting the isomeric molecular structure of poly-viologen EC chromophores is an effective way to control their EC performance. • Three isomeric poly-viologens are designed and synthesized for electrochromic (EC) chromophores. • Poly-viologens with a larger hydrodynamic size exhibit a lower diffusivity and a higher memory effect. • EC devices with meta -poly-viologens consume very low power of ∼3.54 μW/cm 2 to maintain colored state.

Investigation of N–S-based graphene quantum dot on sodium alginate with ammonium thiocyanate (NH4SCN) biopolymer electrolyte for the application of electrochemical devices

Investigation of N–S-based graphene quantum dot on sodium alginate with ammonium thiocyanate (NH4SCN) biopolymer electrolyte for the application of electrochemical devices

Synergistic effect of sodium content for tuning Sm2O3 as a stable electrolyte in proton ceramic fuel cells

Samarium oxide (Sm2O3), a rare earth sesquioxide, shows that a great potential in proton-conducting fuel cells. However, the stability of Sm2O3 based cell remains a challenge. Herein we reported a facile method for enhancing the stability via the incorporation of sodium content into Sm2O3. This study discloses that the existence of sodium induces phase transition of Sm2O3 from monoclinic to cubic phase beneficial for fast proton transportation. Further mechanism investigation reveals that the cubic phase structure of Sm2O3 is stabilized resulting from substitution of sodium. Compared with commercial Sm2O3 (CSM), the fuel cell employing Na–Sm2O3 (NSM) as electrolyte delivers an improved peak power density of 570 mW cm−2 and the extended stability over 100 h under 130 mWcm−2 at 520 °C. In this study, NSM is successfully developed as a stable electrolyte material for proton conduct fuel cells, expanding its application in electrochemical devices.

Studies on the ions transportation behavior of alginate doped with H+ carrier-based polymer electrolytes

In the present work, amorphous bio-based polymer electrolytes (BBPEs) using alginate polymer as a matrix host and doped with varying amounts of ammonium iodide (NH4I) have been developed via the solution casting technique. The physicochemical properties of alginate-NH4I BBPEs were evaluated by using X-Ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA), electrical impedance spectroscopy (EIS), and transference number measurement (TNM). The BBPEs film containing 25 wt % of NH4I possessed the highest ionic conductivity of 1.29 × 10−4 S cm−1, the highest amorphous phase, and good thermal stability of up to 234 °C. Based on the Nyquist fitting approaches, the ionic conductivity of the BBPEs was primarily influenced by the ion transportation, which was due to the interplay of segmental motion between the alginate and NH4I, and also the H+ hopping mechanism, as shown by FTIR. The proton transference number (tH+ = 0.41) suggests that alginate BBPEs are promising materials in electrochemical device applications.

Experimental and Theoretical Advances on Single Atom and Atomic Cluster‐Decorated Low‐Dimensional Platforms towards Superior Electrocatalysts

AbstractThe fundamental relationship between structure and properties, which is called “structure‐property”, plays a vital role in the rational designing of high‐performance catalysts for diverse electrocatalytic applications. Low‐dimensional (LD) nanomaterials, including 0D, 1D, 2D materials, combined with low‐nuclearity metal atoms, ranging from single atoms to subnanometer clusters, are currently emerging as rising star nanoarchitectures for heterogeneous catalysis due to their well‐defined active sites and unbeatable metal utilization efficiencies. In this work, a comprehensive experimental and theoretical review is provided on the recent development of single atom and atomic cluster‐decorated LD platforms towards some typical clean energy reactions, such as water‐splitting, nitrogen fixation, and carbon dioxide reduction reactions. The upmost attractive structural properties, advanced characterization techniques, and theoretical principles of these low‐nuclearity electrocatalysts as well as their applications in key electrochemical energy devices are also elegantly discussed.

Synthesis of CoFe2O4/MWCNTs Nanohybrid and its Effect on the Optical, Thermal, and Conductivity of PVA/CMC Composite as an Application in Electrochemical Devices

Synthesis of CoFe2O4/MWCNTs Nanohybrid and its Effect on the Optical, Thermal, and Conductivity of PVA/CMC Composite as an Application in Electrochemical Devices

Inorganic‐Organic Hybrid Anion Conducting Membranes Based on Ammonium‐Functionalized Polyethylene Pyrrole‐Polyethylene Ketone Copolymer

Back Cover: In article number 2100409 by Voto Di Novo and co-workers, the incorporation of tantalum oxide into trimethylammonium-functionalized polyethylene pyrrole-co-polyethylene ketone is carried out for the preparation of inorganic–organic hybrid anion exchange membranes, which are promising candidates for application in electrochemical energy conversion devices.

Effect of graphene quantum dot on sodium alginate with ammonium formate (NH4HCO2) biopolymer electrolytes for the application of electrochemical devices

Effect of graphene quantum dot on sodium alginate with ammonium formate (NH4HCO2) biopolymer electrolytes for the application of electrochemical devices

Ultrathin microporous carbon/few-layer graphene heterostructure for supercapacitor application

The heterostructure consisting of ultrathin microporous carbon and graphene can exhibit many interesting properties benefiting from their unique physicochemical structure, and thus possess a great potential application in electrochemical energy storage devices. Herein, we report a novel catalysis strategy to construct nanometer-thick microporous carbon/few-layer graphene (FLG) heterostructure in the tens-of-nanometer-thick shells of hollow carbon spheres (HCSs). The thickness of microporous carbon in heterostructure can be reduced by intercalating more FLG sheets. Nano-sized thickness increases exposure ratio of micropores and shortens ion transport distance besides good conductivity of FLG sheets. The meso- and macropores in heterostructure further improves ion adsorption of high-density open micropores. The obtained ultrathin microporous carbon/FLG heterostructure shows high special capacitance (Cs) of 187 F·g−1 at 5.0 mV·s−1 and excellent rate capability. Furthermore, the loading of heterostructure electrode increases by 15 times, the Cs is up to 192 F·g−1 at 5.0 mV·s−1 with more excellent rate performance and robust long-term charge-discharge recyclability. After the loading mass increased by 29 times (2.85 mg·cm−2), the electrochemical performance still remains stable, indicating a great potential for supercapacitor application. The mechanism behind these phenomena was studied.

Silver Nanoparticle Decorated on Reduced Graphene Oxide-Wrapped Manganese Oxide Nanorods as Electrode Materials for High-Performance Electrochemical Devices

In this work, silver nanoparticles decorated on reduced graphene oxide (rGO) wrapped manganese oxide nanorods (Ag-rGO@MnO2) were synthesized for an active electrode material. MnO2 nanorods were synthesized via a hydrothermal route, and their coating with GO and subsequent reduction at a higher temperature resulted in rGO@MnO2. A further addition of Ag on rGO@MnO2 was performed by dispersing rGO@MnO2 in AgNO3 solution and its subsequent reduction by NaBH4. X-ray diffraction (XRD) analysis showed peaks corresponding to MnO2 and Ag, and the absence of a peak at 2θ = 26° confirmed a few layered coatings of rGO and the absence of any graphitic impurities. Morphological analysis showed Ag nanoparticles anchored on rGO coated MnO2 nanorods. Apart from this, all other characterization techniques also confirmed the successful fabrication of Ag-rGO@MnO2. The electrochemical performance examined by cyclic voltammetry and the galvanic charge–discharge technique showed that Ag-rGO@MnO2 has a superior capacitive value (675 Fg−1) as compared to the specific capacitance value of rGO@MnO2 (306.25 Fg−1) and MnO2 (293.75 Fg−1). Furthermore, the electrode based on Ag-rGO@MnO2 nanocomposite showed an excellent capacity retention of 95% after 3000 cycles. The above results showed that Ag-rGO@MnO2 nanocomposites can be considered an active electrode material for future applications in electrochemical devices.

Delafossite CuCrO2 nanoparticles as possible electrode material for electrochemical supercapacitor

Delafossites are popularly known materials for thermoelectric and electrochemical device applications due to their layered structural features. In this paper, delafossite CuCrO2 nanoparticles (NPs) have been synthesized using a simple chemical procedure and are investigated as a supercapacitor material. To determine the phases of delafossite CuCrO2 NPs, the morphological and phase formation experiments were conducted using diffraction patterns and microscopic analysis. The cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) studies were performed to evaluate the supercapacitative behavior of delafossite CuCrO2 NPs. As prepared delafossite CuCrO2 NPs based electrode showed an outstanding electrochemical property as compared to annealed delafossite CuCrO2 NPs at 300–500 °C. A good specific capacitance of ∼464.7 Fg-1 at 0.01 Vs-1 was found for the fabricated supercapacitor using non-annealed delafossite CuCrO2 NPs based electrode, which was further validated by GCD results. The electrochemical supercapacitor fabricated with both non-annealed and annealed delafossite CuCrO2 NPs displayed considerably the outstanding cycling stability by maintaining up to ∼88% after 5000 cycles. This work sets the pace for a new and efficient method of preparing delafossite CuCrO2 for high-performance electrochemical supercapacitors.

Studies on the effect of H+ carrier toward ionic conduction properties in alginate-ammonium sulfate complexes–based polymer electrolytes system

The present work highlights the contribution of ammonium sulfate (NH4)2SO4 as H+ carriers in alginate-based solid polymer electrolytes (SPEs) that were successfully prepared via a solution casting technique. The Fourier transform infrared analysis revealed that molecular interactions between the host polymer and the ionic dopant complexes occurred at the wavenumbers 3700–2500 cm−1, 1800–1500 cm−1, and 1200–900 cm−1. These regions corresponded to the O-H stretching, COO− and C-O-C, moieties of alginate, respectively, which coordinated with the H+ carrier from (NH4)2SO4. At ambient temperature, the optimum ionic conductivity was obtained at 3.01 × 10−5 S cm−1 for the sample containing 10 wt.% of (NH4)2SO4. The IR-deconvolution approach shows that the ionic conduction enhancement is governed by the ionic mobility and the diffusion coefficient of H+ carriers, and the findings show that the present biopolymer, which is an alginate-based SPEs system, has an excellent possibility to be used as electrolytes for application in electrochemical devices.

Design of Ordered Mesoporous CeO2-YSZ Nanocomposite Thin Films with Mixed Ionic/Electronic Conductivity via Surface Engineering.

Mixed ionic and electronic conductors represent a technologically relevant materials system for electrochemical device applications in the field of energy storage and conversion. Here, we report about the design of mixed-conducting nanocomposites by facile surface modification using atomic layer deposition (ALD). ALD is the method of choice, as it allows coating of even complex surfaces. Thermally stable mesoporous thin films of 8 mol-% yttria-stabilized zirconia (YSZ) with different pore sizes of 17, 24, and 40 nm were prepared through an evaporation-induced self-assembly process. The free surface of the YSZ films was uniformly coated via ALD with a ceria layer of either 3 or 7 nm thickness. Electrochemical impedance spectroscopy was utilized to probe the influence of the coating on the charge-transport properties. Interestingly, the porosity is found to have no effect at all. In contrast, the thickness of the ceria surface layer plays an important role. While the nanocomposites with a 7 nm coating only show ionic conductivity, those with a 3 nm coating exhibit mixed conductivity. The results highlight the possibility of tailoring the electrical transport properties by varying the coating thickness, thereby providing innovative design principles for the next-generation electrochemical devices.

Rational design of porous Ru‐doped CuO nanoarray on carbon cloth: Toward reversible catalyst layer for efficient Li‐O 2 batteries

Until now, in case of Li-O2 batteries, catalyst materials are applied by simple mixing with carbon black, which causes large overpotential due to limited active surface of the catalyst, leading to low energy efficiency and short cycle life. Accordingly, in previous studies, significant advances have been witnessed in the synthesis of various electrode materials with three-dimensional (3-D) structures for application in electrochemical energy storage devices. Herein, the 1-D@3-D catalyst layer design and efficient active site formation strategy help to enable an efficient Li-O2 battery. In particular, it should be noted that the 1-D@3-D catalyst layer has great potential for maximizing the active contact area between the electrolyte and the catalyst materials and promoting the rapid diffusion of products and reactants through their stereoscopic structure. The 1-D Ru-doped CuO nanorod array on 3-D carbon cloth (Ru-CuO/RuO2@CC) is demonstrated via 7,7,8,8-Tetracyanoquinodimethane-solution deposition, and thermal oxidation process. A comprehensive kinetic study using linear sweep voltammetry reveals that the Ru-CuO/RuO2@CC has superior ORR/OER performance compared to a CuO nanorods-loaded carbon cloth and a CuO/RuO2 nanoparticles-loaded carbon cloth. The Ru-CuO/RuO2@CC as a catalyst layer combined cell is achieved 1.0 mA h cm−2 (=3075 mA h gc−1) during 30 cycles with a low overpotential decay rate of 0.88% per cycle.

Preparation of PEEK/MWCNT nanocomposites via MWCNT-induced interfacial crystallization mediated compatibilization

Polymer nanocomposites based on high melting temperature semi-crystalline polymers are difficult to prepare because of the limited means available to achieve good nanoparticle dispersion for greatly improved properties. In this study, we demonstrate an alternative strategy for preparation of high-performance PEEK/MWCNT nanocomposites via an interfacial crystallization approach. The utilization of polyetheretherketimine (PEEKt) to prepare PEEK nanocomposites eliminates the difficult solvent issues and enables solution mixing and subsequent crystallization of PEEK on MWCNTs. This strategy facilitates a homogeneous dispersion of pristine MWCNTs into the PEEK matrix without any need of surfactant or compatibilizer. Upon drying, the PEEK/MWCNT powder were then molded into various dimensions for mechanical property measurements. As expected, significant improvements are realized. The PEEK/MWCNT nanocomposites that exhibit good dispersion of MWCNT in PEEK are ideal for applications in energy production field, electrochemical devices, and coatings under harsh conditions.

A versatile role of WO3 and MoO3 in electrical transport in phosphate glasses

Phosphate glasses containing transition metal oxides such as MoO3 and WO3 are well-known for their semiconducting nature with polaronic conduction mechanism. These glasses can also accommodate a relatively high amount of alkali and silver oxides which give rise to ionic conductivity. Such a large compositional and preparation variability enables tuning of the types and mechanisms of the electrical conduction and makes these materials attractive for application in modern electrochemical devices. In this contribution, we discuss various factors that influence electrical transport in these glasses, from simple binary WO3/MoO3-P2O5 systems to complex ones containing variable amounts of alkali/silver oxides. Interestingly, WO3 and MoO3 can have very different roles in the electrical conduction in these materials. While MoO3 contributes weakly via polaronic transport in phosphate glasses, it strongly increases the mobility of alkali/silver ions by forming the mixed phosphate-molybdate network. On the other hand, the role of WO3 depends on the glass composition; it can contribute either directly, by introducing significant polaronic conductivity, or indirectly, by facilitating the transport of alkali/silver ions. The former behaviour is related to the formation of clusters of tungsten units in the glass network which enable fast transport of polarons whereas the latter one originates from the facilitating effect of mixed phosphate-tungstate units on the dynamics of alkali ions.

Effect of Different Cations on Ion-Transport Behavior in Polymer Gel Electrolytes Intended for Application in Flexible Electrochemical Devices

Effect of Different Cations on Ion-Transport Behavior in Polymer Gel Electrolytes Intended for Application in Flexible Electrochemical Devices

Covalent organic frameworks: Design and applications in electrochemical energy storage devices

AbstractAs an emerging class of crystalline organic material, covalent organic frameworks (COFs) possess uniform porosity, versatile functionality, and precise control over designated structures. Aside from the favorable charge and mass transport pathways offered by the porous framework, COFs can also exhibit designed reversible redox activity. In the past few years, their potential has attracted a great deal of attention for charge storage and transport applications in various electrochemical energy storage devices, and numerous design strategies have been proposed to enhance the corresponding electrochemical properties. This review summarizes the working principle and synthesis methods of COFs and discusses significant findings for supercapacitors and various rechargeable battery systems, emphasizing the representative design strategies and their underlying relationship with electrochemical performances. In addition, key advances achieved by computations are highlighted along with the challenges and prospects in this field.image