Electrochemical Power Research Articles

Polypyrrole coated g-C3N4/rGO/S composite as sulfur host for high stability lithium-sulfur batteries

Lithium-sulfur batteries (LSBs) are next-generation electrochemical power devices. However, the poor electrical conductivity of sulfur and the shuttle effect by mediators generated during charging and discharging remain important issues to be addressed. In this study, to overcome these issues, a sulfur-loaded g-C3N4 and rGO composite was coated with PPy using a polymerization method with pyrrole (g-C3N4/rGO/S@PPy) to fabricate a cathode for high-performance LSBs. g-C3N4/rGO/S@PPy demonstrated a high capacity of 1189 mAh g−1 and high retention of 91% after 200 cycles. Furthermore, even under a high sulfur loading of 5 mg cm−2, g-C3N4/rGO/S@PPy showed a high areal capacity of 5.5 mAh cm−2, comparable to that of commercial lithium-ion batteries. PPy as the conducting polymer coated on g-C3N4/rGO/S can facilitate the electronic conduction in the electrode and suppress the dissolution of Li-polysulfide formed during cycling, exhibiting improved stability in the LSB.

High-safety composite solid electrolyte based on inorganic matrix for solid-state lithium-metal batteries

Composite solid electrolytes (CSEs) combine the advantages of polymer electrolytes and inorganic ceramic electrolytes, which have attracted increasing attention for solid-state lithium-metal batteries. However, the most studied polymer-based CSEs are easily ignited and can be penetrated by lithium (Li) dendrite, leading to safety issue. Herein, we report CSEs with very high inorganic ceramic loadings of >90% by a cold sintering method at a low temperature of 200°C. The ceramic-based CSEs show better safety and mechanical properties than polymer-based CSEs. The Li symmetric cell–symmetric Li-ion cells have the same material as the positive and negative electrode [when cells are assembled one would already contain lithium and the other would not]–using the ceramic-based CSE delivers a stable cycling performance of over 550 h at the current density of 0.3 mA/cm2. More importantly, according to the electrochemical impedance spectroscopy (EIS), Debye diagram, and power law equation, the Li-ion conduction mechanism in CSEs is systematically investigated. Using a modified brick layer model, the conductivities for Li-ions transport parallel with ceramic/polymer interfaces are calculated to be five orders of magnitudes higher than that perpendicular to the interfaces. This work provides a new analytical method for inorganic matrix based CSEs for high-safety batteries and conducts an in-depth research on the ion conduction mechanism.

Materials Based on Vanadium Oxide Nanofibers for Electrodes in Electrochemical Power Sources

Materials Based on Vanadium Oxide Nanofibers for Electrodes in Electrochemical Power Sources

A Battery-Free Sustainable Powertrain Solution for Hydrogen Fuel Cell City Transit Bus Application

The paper presents a sustainable electric powertrain for a transit city bus featuring an electrochemical battery-free power unit consisting of a hydrogen fuel cell stack and a kinetic energy storage system based on high-speed flywheels. A rare-earth free high-efficiency motor technology is adopted to pursue a more sustainable vehicle architecture by limiting the use of critical raw materials. A suitable dynamic energetic model of the full vehicle powertrain has been developed to investigate the feasibility of the traction system and the related energy management control strategy. The model includes losses characterisation, as a function of the load, of the main components of the powertrain by using experimental tests and literature data. The performance of the proposed solution is evaluated by simulating a vehicle mission on an urban path in real traffic conditions. Considerations about the effectiveness of the traction system are discussed.

Electrical and structural characteristics of fish skin gelatin as alternative biopolymer electrolyte

This article presented new sequences of fish gelatin (FG) as a polymer host for solid polymer electrolytes (SPEs) impregnated with ammonium nitrate (NH4NO3) and the impact of different amounts of salt on the properties of the formed electrolyte were investigated. X-ray diffraction (XRD) analysis revealed that the electrolyte containing 25 wt.% NH4NO3 salt to be the most amorphous in nature. Fourier transform infrared (FTIR) spectroscopy analysis showed that the peak of amide III shifted to a lower wavenumber as salt increased to 25 wt.%, indicating the occurrence of interaction between the salt and polymer. The effect of variation amount of salt on the film morphology was studied using FESEM. The ionic conductivity of the undoped pure FG film at room temperature recorded a maximum value of at 25 wt.% NH4NO3 and the activation energy dropped to 0.454 eV. All electrolytes showed a linear conductivity-temperature plot at elevated temperatures, indicating that they all follow the Arrhenius rule. All of the electrolytes used in this study are non-Debye type, according to dielectric analysis. The findings provided in this article could help to improve the usage of FG as an alternate source of SPE in electrochemical power sources as a replacement for hazardous electrolytes.

Construction of Charge Transport Channels at the NiOx/Perovskite Interface through Moderate Dipoles toward Highly Efficient Inverted Solar Cells.

NiOx-based perovskite solar cells (PSCs) have attracted much attention because of their low fabrication temperature, suppressed hysteresis, and superior stability. However, the poor interfacial contacts between NiOx and perovskite layers always limit the progress of PSCs. Here, we applied 2-thiophenemethylamine (TPMA) as charge transport channels at the interface between NiOx and perovskite layers. The introduction of TPMA provides moderate dipole moment pointing to the perovskite side and effectively promotes the charge transportation. Meanwhile, TPMA anchorage also passivates the defect states at the surfaces of both NiOx and MAPbI3, which compensates the voltage loss due to the change in NiOx work function induced by the dipole. Thus, the device performance has been significantly enhanced in both electrochemical properties and power conversion efficiency. Our work has demonstrated a new way of improving current and voltage in the NiOx-based PSCs simultaneously through a moderate interfacial dipole moment toward highly efficient PSCs.

An experimental study on gas and liquid two-phase flow in orientated-type flow channels of proton exchange membrane fuel cells by using a side-view method

Proton exchange membrane fuel cells are widely utilized in the areas of aerospace, military and vehicles. Enhancing the reactant transportation and improving water, heat management can effectively increase the electrochemical reaction rate and power output. Orientated-type flow channels have been proved to be effective on improving mass transporting and enhancing performance. In this study, a flow field plate with transparent observation window, whose channel side wall is designed as transparent side-plates, is fabricated to achieve the side-view observation on liquid movement behaviors inside fuel cells. The visualization results of reactant gas and liquid water generation and flowing behaviors in channel regions are observed through the side direction for the first time. Experimental results infer that: orientated-type flow channels having baffles affect droplet generation, moving and shape in gas flow channels, and higher current densities result in more liquid water generation. The baffle downstream region having sudden expanded region slows down droplet moving, and baffle upstream sides accelerates droplet moving. Moreover, the generated heat of electrochemical reaction cannot satisfy maintaining a higher cell working temperature requirement, and an extra heating procedure is required.

Barium 5-(tert-butyl)-2,3-dihydroxybenzenesulfonate

Catechols and their derivatives attract great scientific interest due to the broad spectrum of their functional properties, including complexation, redox behavior, association ability and antioxidant activity. Because of the low molecular mass and two-electron redox process, they are considered to be a promising energy storage compound in different types of electrochemical power sources, such as metal-ion batteries or redox flow batteries. Herein, we report a preparation of the sterically hindered sulfonated catechol, namely the barium salt of 5-(tert-butyl)-2,3-dihydroxybenzenesulfonic acid, by the direct sulfonation of 4-tert-butylcatechol, by concentrated sulfuric acid. The proposed procedure is green and atom-economic, providing the desired product in high yield after simple purification. The solvent-free procedure is inexpensive and highly scalable, which enables direct industrial production of the title product. The resulting product was characterized by the 1H and 13C nuclear magnetic resonance (NMR) and ESI-high resolution mass spectrometry (ESI-HRMS).

Towards health-aware energy management strategies in fuel cell hybrid electric vehicles: A review

An energy management strategy (EMS) is responsible for distributing the power between the electrochemical power sources of a fuel cell hybrid electric vehicle (FCHEV) with a view to minimizing the hydrogen consumption and maximizing the lifetime of the system. However, the energetic characteristics of the electrochemical devices (fuel cell, battery, and supercapacitor) are time-varying due to the influence of ageing, and different ambient and operating conditions. Any drift in the characteristics of the power sources can lead to the mismanagement of an EMS. According to the literature, ignorance of health adaptation can increase the hydrogen consumption from almost 6.5%–24% depending on the EMS. Therefore, it is necessary to develop a strategy which is aware of the actual state of the components while conducting the power split. Health monitoring techniques are potential candidates to deal with the uncertainties arising from the mentioned factors. In this respect, this paper first puts forward a concise review of the general modeling techniques which are essential for developing precise health monitoring techniques and in turn EMSs. Subsequently, the utilized methods for prognosis, diagnosis, and health state tracking of each of the mentioned power sources in a FCHEV are introduced. Then, a new taxonomy for the classification of the EMSs based on their health-awareness is proposed based on which three categories of prognostic-based, diagnostic-based, and systemic EMSs are formed. Each category is thoroughly explained, and a state-of-the-art review of these health-aware EMSs is presented. Finally, future perspectives of this new line of research and development are discussed before drawing a conclusion. • Health-awareness necessity in energy management strategy design is highlighted. • Health unawareness could lead to hydrogen consumption increase (6.5%–24%). • Online estimation techniques in electrochemical devices are discussed. • New categories for energy management of hybrid fuel cell vehicles are introduced. • Concepts of prognostic-, diagnostic-, and systemic-based strategies are explained.

A new high: Cannabis as a budding source of carbon-based materials for electrochemical power sources

Cannabis sativa L., a low-cost, fast-growing herbaceous plant, is seeing a resurgence in widespread cultivation as a result of new policies and product drive. Its biodegradable and environmentally benign nature coupled with its high specific surface area and three-dimensional hierarchal structure makes it an excellent candidate for use as a biomass-derived carbon material for electrochemical power sources. It is proposed that this ‘wonder crop’ could have an important role in the energy transition by providing high-functioning carbon-based materials for electrochemistry. In this article, all instances of C. sativa usage in batteries, fuel cells and supercapacitors are discussed with a focus on highlighting the high capacity, rate capability, capacitance, current density and half-wave potential that can be achieved with its utilisation in the field.

Valence Engineering of Polyvalent Cobalt Encapsulated in a Carbon Nanofiber as an Efficient Trifunctional Electrocatalyst for the Zn-Air Battery and Overall Water Splitting.

The rapid development of electrochemical power systems has prompted high demand for nonprecious trifunctional electrocatalysts with superior performance, prolonged stability, and low cost for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). Here, a valence engineering strategy is devised to construct a morphology with polyvalent cobalt encapsulated in nitrogen-doped carbon nanofibers (Co/N-CNFs). The diverse cobalt valence states of the Co/N-CNF catalysts contribute to their excellent catalytic effect and high durability in multiple electrochemical processes. The optimal Co/N-CNF catalyst fabricated exhibits a high half-wave potential of ORR (0.86 V) and low overpotentials of OER (380 mV) and HER (241 mV) at 10 mA cm-2. The Co/N-CNF-based Zn-air battery possesses a high charge-discharge efficiency as well as a good cycle stability (50 h at 10 mA cm-2 and 120 h at 20 mA cm-2), much superior to the Pt/C-based batteries. Furthermore, the Co/N-CNF catalyst could perform efficient overall water splitting.

Consistency Analysis of Large-scale Energy Storage Batteries

With the development of large-scale electrochemical energy storage power stations, lithium-ion batteries have unique advantages in terms of re-energy density, power density, and cycle life, and are applied to power system energy storage devices. However, behind the rapid development, there are many key issues unanswered, which are likely to lead to various safety accidents. Therefore, it is very important to conduct consistency analysis of lithium batteries used in large-scale power systems to prepare for system safety assessment. This paper mainly explains the reasons and manifestations of the inconsistency, and based on data mining algorithms, uses the charging voltage curve clustering analysis method based on subtractive clustering to evaluate the consistency of lithium-ion batteries.

Carbon cloth as an important electrode support for the high selective electrosorption of uranium from acidic uranium mine wastewater

An amidoxime modified carbon cloth electrode (CC-AO) was applied for uranium electrosorption at low pH value of 2. Experiments using other carbon-based electrodes were also carried out for comparison. The kinetics, isotherm, selectivity, reusability and power consumption during the uranyl ions (UO22+) electrosorption were studied in-depth. The effects of voltage and frequency on UO22+ selectivity among coexisting ions were investigated. The results showed that UO22+ (20 mg/L), removal by CC-AO was 94.3% at pH = 2 with a high electrosorption capacity of 989.5 mg/g (within 12.5 h). The electric field drove UO22+ to move to the cathode surface and produced UO3·2H2O on CC-AO. Under the optimal electric field (- 2.5 V, 800 Hz), CC-AO achieved the highest UO22+ selectivity in the simulated acidic uranium mine wastewater, and the frequency was the main factor. The CC-AO can be effectively used for seven UO22+ electrosorption-desorption cycles. Moreover, a new index of “unit power consumption for half amount uptake” (PC1/2) was proposed to quantify the power consumption during UO22+ uptake by different electrodes. In electrosorption system, the available area of CC-AO is larger than that of CF-AO, so its electrosorption efficiency for UO22+ is much higher than the latter. The current CC-AO showed clear advantages in terms of electrochemical features, adsorption capacity, selectivity, and power consumption at such low pH condition, indicating an application potential for uranium recovery from acidic uranium mine wastewaters.

Полипорфириновые покрытия на основе металлокомплексов 5,10,15,20-тетракис(3-аминофенил)порфирина в реакции электрокаталитического восстановления кислорода

Carbon-based materials are widespread and promising in areas such as electrochemical and electrocatalytic power generation and can be excellent choices for use as electrode substrates. To increase the efficiency of using carbonaceous materials, the surface of the electrodes is modified with metal complexes of phthalocyanines and porphyrins with electrocatalytic properties. In this work polyporphyrin coatings were obtained on a glassy carbon electrode based on individual metal complexes of 5,10,15,20-tetrakis(3-aminophenyl)porphyrin and a composite based on two metal complexes Fe and Mn. Polymerization was carried out by the electrochemical method in the region of positive values of the potential in the potentiodynamic mode. Electrodeposited polyporphyrin coatings have a developed surface and exhibit catalytic activity in the reaction of oxygen electroreduction. The results of evaluating the catalytic activity of polyporphyrins obtained by various methods are in good agreement with each other and indicate a higher catalytic activity of a composite based on two metal complexes compared to films of individual porphyrins, which suggests the presence of a synergistic effect. Based on the results of our research, we propose potential directions for the creation of electrodes based on glassy carbon modified with polyporphyrins for electrocatalytic oxygen reduction.

Biopolymer-based electrospun fibers in electrochemical devices: versatile platform for energy, environment, and health monitoring.

Electrochemical power tools are regarded as essential keys in a world that is becoming increasingly reliant on fossil fuels in order to meet the challenges of rapidly depleting fossil fuel supplies. Additionally, due to the industrialization of societies and the growth of diseases, the need for sensitive, reliable, inexpensive, and portable sensors and biosensors for noninvasive monitoring of human health and environmental pollution is felt more than ever before. In recent decades, electrospun fibers have emerged as promising candidates for the fabrication of highly efficient electrochemical devices, such as actuators, batteries, fuel cells, supercapacitors, and biosensors. Meanwhile, the use of synthetic polymers in the fabrication of versatile electrochemical devices has raised environmental concerns, leading to an increase in the quest for natural polymers. Natural polymers are primarily derived from microorganisms and plants. Despite the challenges of processing bio-based electrospun fibers, employing natural nanofibers in the fabrication of electrochemical devices has garnered tremendous attention in recent years. Here, various natural polymers and the strategies employed to fabricate various electrospun biopolymers are briefly covered. The recent advances and research strategies used to apply the bio-based electrospun membranes in different electrochemical devices are carefully summarized, along with the scopes in various advanced technologies. A comprehensive and critical discussion about the use of biopolymer-based electrospun fibers as the potential alternative to non-renewable ones in future technologies is briefly highlighted. This review will serve as a field opening platform for using different biopolymer-based electrospun fibers to advance the electrochemical device-based renewable and sustainable technologies, which will be of high interest to a large community. Accordingly, future studies should focus on feasible and cost-effective extraction of biopolymers from natural resources as well as fabrication of high-performance nanofibrous biopolymer-based components applicable in various electrochemical devices.

MESOPOROUS Na2Ti3O7 NANOTUBE-CONSTRUCTED MATERIALS WITH HIERARCHICAL ARCHITECTURE: SYNTHESIS AND PROPERTIES

Recently, design of hierarchical materials with remarkable and unusual properties, useful for practical applications, has become more and more meaningful in nanosciences and nanoengineering. This report presents a method of fabricating Na2Ti3O7-based materials with hierarchical two-level (micro/nano) architecture. The products are microparticles constructed of thin-walled nanotubes having an outer diameter of 6–9 nm, wall thickness of 2–3 nm, and length of several hundred nanometers. The synthesis was carried in hydrothermal conditions at 130 °C for 36 h in a highly alkaline medium (10M NaOH aqueous solution). The obtained hierarchical materials exhibit surface roughness and porosity (specific surface area of 314 m2/g and pore volume of 0.54 cm3/g are achieved) with a narrow pore-size distribution in the mesopore range (average pore diameter is around 5.7 nm). Phase formation of products has been studied as a function of calcination temperature. It was found that Na2Ti3O7-based materials is obtained for calcination conditions of near 350 °C. Higher temperatures (more than 500 °C) favored anatase TiO2 formation. There are no significant changes were detected in morphology and texture of products calcined at 350 °C. An electrical conductivity of over 10–3 S/cm at room temperature was registered for materials. Besides, it is increased for three times after thermal treatment at 350 °C. The results suggest that obtained hierarchical nanotube-constructed porous Na2Ti3O7 microparticles can be involved for various industrial uses, including next generation electrochemical power sources.

Effect of Organic and Non Organic Acids on the Blend PES/PS/PVDF Polymer Membranes Efficiency for Microbial Fuel Cell

In this work proton exchange membranes were prepared by a modified microwave casting solution technique, using the polymers blend (polyethersulfone (PES), polystyrene (PS), polyvinylidenefluride (PVDF)). Modified casting method was used to overcome the poor compatibility between hydrophilic, (PES, PS) and hydrophobic PVDF, by cooling the substrate during the film casting process to (4.5-5.5oC). Membranes were chemically modified by three reaction types to study the differences between their effects on the required properties for microbial fuel cell application. These methods use blend organic sulfonic acid precasting process and sulfonation by sulfuric acid post-casting process (APS), blending organic sulfonic acid precasting process (AS) and sulfonation by sulfuric acid post-casting process (AP). The presence of organic sulfonic acid and the sulfonation were confirmed via FTIR spectra for the membranes. The membranes were characterized by proton conductivity, ion exchange capacity (IEC), [-SO3H] value, and water uptake. MFC is characterized by electrochemical polarization tests and power densities obtained from it were used to evaluate the efficiency of the membrane in the cell.

Electrochemical Characterization of Novel Polyantimonic-Acid-Based Proton Conductors for Low- and Intermediate-Temperature Fuel Cells

The development of novel proton-conducting membrane materials for electrochemical power units, i.e., low temperature fuel cells (FCs), efficiently working up to 300 °C, is a critical problem related to the rapid shift to hydrogen energy. Polyantimonic acid (PAA) is characterized by high conductivity, sufficient thermal stability and can be regarded as a prospective proton-conducting material. However, the fabrication of bulk PAA-based membranes with high proton conductivity remains a challenging task. In the present work, for the first time, the authors report the investigation on proton conductivity of bulk PAA-based membranes in the temperature range 25–250 °C, both in dry air and in moisturized air. Using PAA powder and fluoroplastic as a binder, fully dense cylindrical membranes were formed by cold uniaxial pressing. The structures of the PAA-based membranes were investigated by SEM, EDX, XRD and Raman techniques. STA coupled with in situ thermo-XRD analysis revealed that the obtained membranes corresponded with Sb2O5·3H2O with pyrochlore structure, and that no phase transitions took place up to 330 °C. PAA-based membranes possess a high-grain component of conductivity, 5 × 10−2 S/cm. Grain boundary conductivities of 90PAA and 80PAA membranes increase with relative humidity content and their values change non-linearly in the range 25–250 °C.

Alternative binders for electrodes of electrochemical capacitors: The transition to aqueous and alcohol based solvent electrode processing

The use of new polymeric binder materials on the water and alcohol base in electrochemical power sources is still a relevant and present-day issue. Electrochemical capacitor performances are influenced by binder types and contents in the electrodes. The electrochemical performances of activated carbon based electrochemical capacitors with different polymeric materials such as polyvinylbutyral, polyvinylpyrrolidone, polyvinylflouride and polytetrafluoroethylene were investigated by cyclic voltammetry, galvanostatic charge - discharge and electrochemical impedance spectroscopy. The results obtained can be used for the creation of a new production technique of electrodes and decrease in the electrochemical capacitors prime cost.

Effect of external resistance on microbial electrochemical desalination, sewage treatment, power and resource recovery

Microbial desalination cell (MDC) has attracted attention as an eco-friendly technology to treat sewage and seawater with concurrent recovery of bioelectricity. External resistance (Rext) is one of the main factors that control it’s performances. This study optimized the performance of an MDC for removing COD and salinity at five different Rext of 150, 100, 50, 25, and 10 Ω. Columbic efficiency (CE) was measured to find the best Rext for MDC operation. Voltage polarization demonstrated that the MDC possessed an internal resistance (Rint) of 25–30 Ω and maximum power recovery of 302.25 mW/m2. The highest and lowest recovery of stable electricity was 20.7 mA and 3.6 mA at Rext of 10 and 150 Ω, respectively. The COD removal increased from 21% at Rext of 25 Ω to 57% at Rext of 150 Ω. The CE decreased from 58.3% to 4.32% with the gradual increase of Rext from 25 to 150 Ω suggesting the dominancy of exoelectrogens in biofilm at Rext ≤ Rint. The achieved desalination rate was 47% and 18% at Rext of 10 and 25 Ω, respectively. The performances of investigated MDC showed a great potential for recovering electricity with significant removal of organics from domestic sewage and salt from seawater.