Combination Of Electrode Materials Research Articles

Polyelectrolyte-coated zeolite-templated carbon electrodes for capacitive deionization and energy generation by salinity exchange

As global demands for freshwater and renewable energy intensify, capacitive deionization (CDI) emerges as a promising technique for water purification, desalination, and ionic separation. Reciprocally, energy harvesting has been made possible from exchanging solutions with different salinity, using the so-called capacitive mixing (CapMix) methods, now taking their first steps towards a wider range of application. In all the techniques mentioned, porous electrodes are used in order to maximize the stored charge, making it essential to properly select the material of which the electrode is composed. This work focuses on exploring the performance of zeolite-templated carbon (ZTC) as a highly promising electrode material. ZTC offers ordered pore distribution and high electrical conductivity, making it in principle ideal for energy harvesting and water purification applications. In order to optimize its performance, the surface of the ZTC is for the first time modified by application of polyelectrolyte coatings, resulting in so-called soft electrodes or SEs. This combination of electrode material and functionalization gives rise to a highly efficient and low energy-consuming strategy to fully realize the potential of this carbon material in CDI and CapMix techniques for tackling global freshwater and energy challenges. Energy and power generation values up to 25 mJ and 7.5 mW m−2 have been obtained (with measured potential rises of 131 mV by only exchanging salinities of the bathing solution), which overcome values such as 4.3 mW m−2 previously found in our laboratory under similar conditions.

Thermal profiling of ultracapacitor modules : A layered analysis

This study explores heat dissipation in supercapacitor modules tailored for energy-intensive applications. The research investigates the influence of different electrode material combinations on key performance parameters. Employing MATLAB and COMSOL simulations, the thermal conductivity of various layers within the supercapacitor module is analyzed. Findings reveal that polythene separators, responsible for encapsulating and segregating the module’s electrodes, represent critical points for controlled heat transfer. Significantly, the use of metal oxide in electrode construction contributes positively to regulated heat dissipation. Substituting polythene separators with synthesized materials is proposed to optimize heat dissipation. This research pioneers a data-driven analysis and software simulations to augment the study’s outcomes.

Impact of Formulation and Slurry Properties on Lithium‐ion Electrode Manufacturing

AbstractThe characteristics and performance of lithium‐ion batteries typically rely on the precise combination of materials in their component electrodes. Understanding the impact of this formulation and the interdependencies between each component is critical in optimising cell performance. Such optimisation is difficult as the cost and effort for the myriad of possible combinations is too high. This problem is addressed by combining a design of experiments (DoE) and advanced statistical machine learning approach with comprehensive experimental characterisation of electrode slurries and coatings. An industry relevant graphite anode system is used, and with the aid of DoE, less than 30 experiments are defined to map impact of different weight fractions of active material (80–96 wt%), conductive additive (Carbon Black at 1–10 wt%) and a two‐component binder system (Carboxymethyl Cellulose (CMC) at 1–3 wt% and Styrene Butadiene Rubber (SBR), at 1–7 wt%). Using Explainable Machine Learning (XML) methods, correlations between the formulation, slurry weight percentage (30–50 wt% in water) and coating speed (1–15 m/min) are quantified. Slurry viscosity, while known to depend on the CMC concentration, is also heavily influenced by carbon black and SBR when at high concentration, as is common in research. Viscosity increasing components also improve adhesion, by improving dispersion and hindering binder migration. Conductivity of the coating on current collector is sensitive to the current collector‐coating interface, which makes it a highly useful probe. Improvements in cell capacity are observed with higher viscosity formulations (High weight percentage, CMC content), attributed to reduction in migration and slumping of the slurry on the current collector. SBR had a negative impact at any concentration due to its insulating nature, and carbon black reduces gravimetric capacity when included at high concentrations. The insights from this study facilitate the formulation optimisation of electrodes providing improved slurry design rules for future high performance electrode manufacturing.

Tailoring solid-electrolyte interphase and solvation structure for subzero temperature, fast-charging, and long-cycle-life sodium-ion batteries

The sluggish Na+ reaction kinetics with carbon materials limits the fast-charging capability, Coulombic efficiency, and cycle life of sodium-ion batteries, especially at low temperatures. Herein, free-standing carbon nanofiber films, with controllable crystallinity and surface chemistry, are used as a platform to investigate the correlation between Na+ reaction kinetics, storage mechanism, and electrolyte environment. The ion solvation effect and solid-electrolyte interphase (SEI) properties determine the kinetics and storage mechanism. A strong Na+-solvent interaction, such as Na+-diglyme, tends to form a “pseudo-SEI” layer dominated by anion decomposition, enabling fast Na+-solvent co-intercalation kinetics. Tuning the SEI chemistries by pre-cycling in the weakly solvated electrolyte (e.g., ester electrolyte), the intercalation capacity rapidly disappears due to the high energy barrier for Na+ transport. Such mechanistic insights allow us to develop the optimal combination of electrode materials and electrolyte chemistry to achieve high initial Coulombic efficiency, ultra-long cycle life under fast charging, and excellent low-temperature performance.

English

Microbial fuel cells (MFCs) are considered as one of the best prospective natural resources to be discovered on the way to reduce the dependence on fossil fuel-based electricity generation. However, low power generations from MFCs, expensive electrode materials, and the inability to scale-ups MFCs to industrially relevant capacities have made the usage of MFC even worse. The utilization of MFCs in the area of electro-chemistry and thermal science can be very promising in energy storage aspects. In this current study, we studied various combinations of electrode materials and processes that can be applied to construct economical MFCs on small scale. To figure out the best suited MFC setup, MFC systems are prepared using different electrode materials and impacts of these materials on voltage generation are investigated. The cells are observed for 10 h, and voltage generation is witnessed by natural chemical reaction. Then, voltage, current, and power density curves are generated. Next, a pseudo-two-dimensional (2D) physics-based mathematical full cell model is developed to investigate the best suited MFC as a potential energy storage device. It is observed that the numerical results generated from the model are in good agreement with those obtained from the experimental analyses. Hence, the model should be able to predict the better performing anode and cathode materials to build microbial fuel cells having a maximum amount of voltage storage capacity in a specific period. Details of this work will provide more useful information on the concept of MFC and design guidelines for several applications such as energy storage and transformation. Key words: Bacteria, electro-chemistry, physics-based, power, energy storage device, electrodes.

A Novel Dye-Sensitized Solar Cell Structure Based on Metal Photoanode without FTO/ITO.

Traditional dye-sensitized solar cells (DSSC) use FTO/ITO containing expensive rare elements as electrodes, which are difficult to meet the requirements of flexibility. A new type of flexible DSSC structure with all-metal electrodes without rare elements is proposed in this paper. Firstly, a light-receiving layer was prepared outside the metal photoanode with small holes to realize the continuous oxidation-reduction reaction in the electrolyte; Secondly, the processing technology of the porous titanium dioxide (TiO2) film was analyzed. By testing the J–V characteristics, it was found that the performance is better when the heating rate is slow. Finally, the effects of different electrode material combinations were compared through experiments. Our results imply that in the case of all stainless-steel electrodes, the open-circuit voltage can reach 0.73 V, and in the case of a titanium photoanode, the photoelectric conversion efficiency can reach 3.86%.

Electrochemical Immunosensors for Quantification of Procalcitonin: Progress and Prospects

Human procalcitonin (PCT) is a peptide precursor of the calcium-regulating hormone calcitonin. Traditionally, PCT has been used as a biomarker for severe bacterial infections and sepsis. It has also been recently identified as a potential marker for COVID-19. Normally, serum PCT is intracellularly cleaved to calcitonin, which lowers the levels of PCT (<0.01 ng/mL). In severe infectious diseases and sepsis, serum PCT levels increase above 100 ng/mL in response to pro-inflammatory stimulation. Development of sensors for specific quantification of PCT has resulted in considerable improvement in the sensitivity, linear range and rapid response. Among the various sensing strategies, electrochemical platforms have been extensively investigated owing to their cost-effectiveness, ease of fabrication and portability. Sandwich-type electrochemical immunoassays based on the specific antigen–antibody interactions with an electrochemical transducer and use of nanointerfaces has augmented the electrochemical response of the sensors towards PCT. Identification of a superior combination of electrode material and nanointerface, and translation of the sensing platform into flexible and disposable substrates are under active investigation towards development of a point-of-care device for PCT detection. This review provides an overview of the existing detection strategies and limitations of PCT electrochemical immunosensors, and the emerging directions to address these lacunae.

Solar based hybrid combination of electrocoagulation and filtration process in domestic greywater treatment

Objectives: To evaluate the importance of solar-based Electrocoagulation followed by the filtration process in treating the domestic greywater, analyze each operational process’s performance process in highlighting the cost, efficiency and reuse conditions. Analysis: This research aimed to see if the continuous mode EC technique could treat Greywater (GW) with batterypowered solar energy. The EC process running on solar energy is used as a single unit method for Greywater treatment. This explores the hybrid electrocoagulation and filtration process with different electrode material combinations with a flow rate; based on this, and the impact tests are carried out on the flexibility of continuous mode, anode and cathode efficiency. Findings: In this experiment, using a combination of electrodes with different material having continuous flow find about removal efficiencies of different characteristics like COD, Total dissolved solids, Total suspended solids, pH and Turbidity with the variable in the supply of current with fix detention time. Novelty:Experimental approach based on Solar based Electrocoagulation with filtration mechanism is the new concept of approach for treating Domestic Greywater Keywords: Domestic Greywater; Solar energy; Electrocoagulation; Continuous mode; Controlled flowrate; Filtration

Mechanisms of charge accumulation in electrochemical systems formed based on of nanoporous carbon and manganese oxide

In this work, the processes occurring in electrochemical systems based on nanoporous carbon material and manganese oxide in an aqueous solution of lithium sulfate are analyzed. Furthermore, it is shows the feasibility of these materials combination cycling as electrodes of a hybrid electrochemical capacitor. The combination of electrode materials with different mechanisms of charge accumulation was determined. Consequently, an increase in the accumulated energy by more than 25% by the formation of an electric double layer and the occurrence of redox reactions based on carbon and manganese oxide respectively. The laboratory sample of an aqueous electrolyte hybrid electrochemical capacitor was formed. Moreover, the laboratory sample is electrochemically stable at an operating voltage of 2 V.

Electrode material studies and cell voltage characteristics of the in situ water electrolysis performed in a pH-neutral electrolyte in bioelectrochemical systems

Hydrogen-oxidizing bacteria (HOB) have been shown to be promising micro-organisms for the reduction of carbon dioxide to a wide range of value-added products in bioelectrochemical systems with in situ water electrolysis of the cultivation medium, also known as a hybrid biological-inorganic systems (HBI). However, scaling up of this process requires overcoming the inherent constraints of the low energy efficiency partly associated with the pH-neutral electrolyte with low conductivity. Most of the research in the field is concentrated on the bacterial cultivation, whereas the analysis and evaluation of the electrode material performance have received little attention in the literature so far. Therefore, in the present work, in situ electrolysis of a pH-neutral medium for HOB cultivation was performed with different combinations of electrode materials. Besides conventional electrode types, electrodes with coatings made of earth-abundant cobalt and a nickel-iron alloy, known for their catalytic activity for the kinetically sluggish oxygen evolution reaction (OER), were prepared and tested as potential substitutes for catalysts made of precious metals. The cultivation of HOB with in situ water electrolysis has been successfully tested in a small scale electrobioreactor in order to support the experimental results. A simplified water electrolysis model was developed and applied to evaluate the current-voltage characteristics of an bioelectrochemical system prototype. Application of the developed model allows quantitative evaluation and comparison of reversible, ohmic, and activation overvoltages of different electrode sets. The modeling results were found to agree well with the experimental data. The developed model and the data gathered can be applied to further investigation, simulation, and optimization of HBI systems.

Surface Photovoltage Spectroscopy Study of Organo-Lead Perovskite Solar Cells.

The field of organo-lead perovskite absorbers for solar cells is developing rapidly, with open-circuit voltage of reported devices already approaching the maximal theoretical voltage. Obtaining such high voltages on spun-cast or evaporated thin films is intriguing and calls for detailed investigation of the source of photovoltage in those devices. We present here a study of the roles of the selective contacts to methylammonium lead iodide chloride (MAPbI3-xClx) using surface photovoltage spectroscopy. By depositing and characterizing each layer at a time, we show that the electron-extracting interface is more than twice as effective as the hole-extracting interface in generating photovoltage, for several combinations of electrode materials. We further observe the existence of an electron-injection related spectral feature at 1.1 eV, which might bear significance for the cell's operation. Our results illustrate the usefulness of SPV spectroscopy in highlighting gaps in cells efficiency and for deepening the understanding of charge injection processes in perovskite-based photovoltaics.

Dynamometer Testing of Planar Mixed-Potential Sensors

Recently strengthened federal regulations are driving the reduction of pollutants emitted from heavy-duty diesel engines. The use of selective catalyst reduction (SCR) and exhaust gas recirculation (EGR) systems combined with regenerative particulate traps have reduced NOx and particulate matter (PM) tailpipe emissions from heavy-duty diesel vehicles by 95%.1 Despite these recent advances, there is a lack of low cost exhaust gas sensor technology to monitor tailpipe emissions and to control and maintain optimized SCR and EGR system efficiencies2. Derivatives of the hugely successful robust, zirconia-based electrochemical sensors currently used for gasoline engine control and OBD in conjunction with three-way catalytic converters, has attracted considerable interest in diesel applications. However, the implementation of the diesel analogue to OBD has proved to be more complicated.Mixed-potential sensors fabricated via well-established commercial manufacturing methods present a promising avenue to enable the widespread utilization of NOx sensing technology. The Materials Synthesis and Integrated Devices group at LANL has worked in collaboration with Electro-Science Laboratories (ESL, King of Prussia, PA) to fabricate planar mixed-potential sensors via the readily scalable, cost-effective high temperature co-fired ceramic (HTCC) technology already employed in the manufacturing of planar O2 λ-sensors.The two sides of the planar, self-heated, tape cast sensor prototype are shown in Figure 1. A Pt-heater with independent leads is printed on the backside of the ceramic substrate. The sensing component consists of dense La1-xSrxCrO3 (LSCrO)- working and Pt-counter electrodes coated with a porous YSZ electrolyte layer. The voltage response of a sensor operated at 490˚C to 100 ppm of varying analyte gases is shown in Figure 2. Operated at open circuit, this combination of electrode materials serves as a sensor for reducing gases, such as hydrocarbons and ammonia. However, the sensor can be transformed to a total NOx sensor by appropriate tuning of the current bias and operating temperature3. The performance of the planar sensors under engine-out conditions was recently evaluated at the Oak Ridge National Laboratory National Transportation Research Center. The sensor was mounted in a quartz tube with the Pt heater resistance set to correspond to an operating temperature of 490˚C. The sensor was placed in the exhaust gas downstream of an orifice regulating the flow to 1000ccm and upstream of the FTIR used to analyze the exhaust gas components. A California Instruments Flame-Ionized Detector (FID) was also used to analyze total hydrocarbon content (THC) immediately upstream of the orifice. Figure 3 shows the sensor response during varying engine operating conditions. The sensor response while operating in hydrocarbon sensing mode (0 bias) during engine start-up is shown in Figure 3a. The sensor response closely tracks the THC measured by the FID, while the THC measured via FTIR lags the response of both the FID and the sensor. Figure 3b shows the sensor response while operating in NOx sensing mode (+0.2 μA bias) while the engine was held at 1600 rpm and EGR was cycled on and off. The sensor response qualitatively tracks the NO concentration in the exhaust stream, with the sensor response becoming more negative with increasing NO, in agreement with the biased response shown in Figure 2. In this work, we will discuss the performance of the planar, mixed-potential sensors under engine-out conditions and compare the dynamometer performance with laboratory measurements.

SELECTION OF APPROPRIATE PROCESS PARAMETERS FOR GAS METAL ARC WELDING OF MEDIUM CARBON STEEL SPECIMENS

Gas Metal Arc Welding (GMAW) is a semi-automated process used widely for accurate welding in the fabrication industry. The selection of appropriate process parameters of GMAW is essential to obtain the desired weld quality. Â In the past, much work has been done investigating a variety of workpiece and electrode material combinations. In the present work, an Analytical Hierarchy Process (AHP) based parametric optimization is tried in gas metal arc welding of C45 medium carbon steel specimens using carbon dioxide as the gas shield. The experiments were performed by varying three process parameters, weld speed, weld voltage and weld current. The AHP facilitates the selection of suitable process parameters to obtain a sound weld. In the present experimental domain, optimal conditions are evaluated to be at a weld voltage of 30 V, weld current of 160 A with a weld speed of 475.75 mm/min. http://dx.doi.org/10.13033/ijahp.v5i2.184

Lifetime Improvement for Full-Width-Array Piezo Ink Jet Print Head Using Matrix Nozzle Arrangement

Upon driving the unimorph type piezoelectric actuator of an ink jet in a high temperature high humidity environment (38°C/80%), many failures occurred after approximately 1 billion pulses. We hypothesized that the failures occurred due to hydrogen that was generated from the electrolysis of water, causing the piezoelectric element to deteriorate. Based on this hypothesis, we examined electrode materials to reduce the frequency of failures. We found that failure rate can be improved if material with high standard electrode potential is used as the electrode material on the high potential side and material with low standard electrode potential is used on the low potential side, and more specifically, if metal oxide is used for the electrode on the low potential side. Based on these findings, a combination of silver palladium for the electrode on the high potential side and stannous oxide (Sn x O y ) for the low potential side was used as the combination of electrode materials that can be formed at low cost. Upon implementing a running test with this combination of electrode materials under a high temperature high humidity environment, we confirmed that failures do not occur even at a continuous drive of 30 billion pulses and that the long-term reliability of the unimorph type piezoelectric actuator improved significantly.

Bismuth/Glassy Carbon Composite Electrode for the Determination of Trace Lead and Cadmium

We examined the use of a bismuth/glassy carbon (Bi/C) composite electrode for the determination of trace amounts of lead and cadmium. Incorporated bismuth powder in the composite electrode was electrochemically dissolved in 0.1 M acetate buffer (pH 4.5) where nanosized bismuth particles were deposited on the glassy carbon at the reduction potential. The anodic stripping voltammetry on the Bi/C composite electrode exhibited well-defined, sharp and undistorted peaks with a favorable resolution for lead and cadmium. Comparing a non-oxidized Bi/C composite electrode with an in-situ-plated bismuth film electrode, the Bi/C composite electrode exhibited superior performance due to its much larger surface area. The limit of detection was 0.41 μ/L for lead and 0.49 μ/L for cadmium. Based on this study, we are able to conclude that various types of composite electrodes for electroanalytical applications can be developed with a prudent combination of electrode materials.

Determination of trace amounts of lead and cadmium using a bismuth/glassy carbon composite electrode

We examined the use of a bismuth–glassy carbon (Bi/C) composite electrode for the determination of trace amounts of lead and cadmium. Incorporated bismuth powder in the composite electrode was electrochemically dissolved in 0.1 M acetate buffer (pH 4.5) where nanosized bismuth particles were deposited on the glassy carbon at the reduction potential. The anodic stripping voltammetry on the Bi/C composite electrode exhibited well-defined, sharp and undistorted peaks with a favorable resolution for lead and cadmium. Comparing a non-oxidized Bi/C composite electrode with an in-situ plated bismuth film electrode, the Bi/C composite electrode exhibited superior performance due to its much larger surface area. The limit of detection was 0.41 μg/L for lead and 0.49 μg/L for cadmium. Based on this study, we are able to conclude that various types of composite electrodes for electroanalytical applications can be developed with a prudent combination of electrode materials.

Aqueous-solution high-voltage resistors: Development, study, and application (review)

Development, studies, and applications of resistors based on aqueous solutions of salts, acids, and their mixtures are reviewed. Aqueous-solution resistors (ASRs) have a number of advantages as compared to resistors of other types: their bulk electric strength reaches 300 kV/cm for pulses of microsecond duration, their energy dissipation in a unit mass of a solution is an order of magnitude higher than that in metals, a liquid recovers rapidly its electric strength after a breakdown, the resistance value can be rapidly adjusted by replacing an electrolyte, resistors can be shaped arbitrarily, their inductance can be as low as a few fractions of 1 nH, they can be used in circuits operating at frequencies of up to ∼1 GHz, they are fire-and explosion-proof, are simple to manufacture, and are inexpensive. The electric characteristics and behavior of solutions in fields of up to 50 kV/cm are refined. A list of combinations of electrode materials and dissolved substances, which operate for a long time, is presented. Criteria are given for considering the permittivity of water in the calculation of the skin-layer depth in a solution. The moisture proofness of ASR cases made of polymer materials is examined. A set of formulas for engineering calculations of several characteristics of ASRs is presented. The procedures of preparing the components, the ASR assembly, and their testing for tightness are described. The electric and service-life characteristics are presented. Along with other ASRs, much attention is being given to the hermetically sealed high-voltage small ASRs developed at the Russian Federal Nuclear Center (VNIIEF). They are serviceable in any positions in volumes with rarefied and compressed gases and oil insulation. Heat-induced changes in the volume of the solution were compensated by the following operations: changes in the geometry of the polymer case of the ASR within the limits of elastic deformations of its walls; profiling of cavities in the electrodes’ walls, so that no gas penetrates from them into the solution at an arbitrary ASR position; and separation of the solution from a hermetically sealed vapor-gaseous cavity in the electrode by an elastic diaphragm. Versions of ASR designs and their characteristics are presented for the following situations: limitation of currents in electric circuits at voltage of up to 100 kV; simulation of high-power loads, including a current of up to 300 kA of a pulsed electron beam; damping of electric oscillations and suppression of reflected pulses; a specified distribution of an electric field along the lengths of insulators for a voltage as high as ∼ 3.5 MV; measurements of parameters of pulse voltage amplitudes of up to ∼2 MV; the application of ASRs as high-voltage dynamic resistive-capacitive elements in circuits of voltage-multiplying generators for reducing the delay time of their operation; etc. This information, systemized for the first time, will be useful for specialists in development, research, and application of ASRs designed for different purposes.

Characteristics of polythiophene surface light emitting diodes

Surface light emitting diodes (SLEDs), in which previously microfabricated electrodes were coated with a conjugated polymer, were made with greatly different electrode spacings (250 nm and 10 or 20 μm) and with different electrode material combinations. The fabrication process allowed us to compare several electrode materials. The SLED structures also enabled imaging of the light emission zone with fluorescence video microscopy. Conventional sandwich structures were also made for comparison (electrode separation 50 nm). In this study, the emitting layer was poly[3-(2′,5′-bis(1″,4″,7″trioxaoctyl)phenyl)-2,2′-bithiophene] (EO–PT), a conjugated polymer based on polythiophene with oligo(ethyleneoxide) side chains. The current–voltage ( I( V)) and light–voltage ( L( V)) characteristics of the SLEDs were largely insensitive to electrode separation except at high voltages, at which the current in the devices with the largest separations was limited. Sandwich structures had the same light output at a given current. Light could be obtained in forward and reverse bias from indium tin oxide (ITO)–aluminum, gold silicide–aluminum, and gold silicide–gold SLEDs, but the turn-on voltages were lowest with the ITO–aluminum devices, and these were also the brightest and most reliable. Adding salt to the EO–PT increased the current and brightness, decreased the turn-on voltages, and made the I( V) characteristics symmetric; thus, a device with an electrode separation of 10 μm had the extraordinarily low turn-on voltage of 6 V. The location of the light emission was at the electron-injecting contact.

Dc corona discharges in -air and CO-air mixtures for various electrode materials

Positive and negative dc corona discharges in CO-air and -air mixtures were applied. Natural humid air was used. The step by step development with time of the formation of gas products after the action of the corona discharge was measured in situ. The discharge tube was situated in an IR gas cell. The IR absorption spectra were scanned from the area of the inter-electrode distance in successive time steps of the action of the discharge (about 1 min). Measurements were performed for three combinations of electrode materials, namely Mo-stainless steel, Mo-brass and Cu-brass. Reflection IR absorption spectra from the surfaces of the electrodes used were scanned after the action of the discharge. The influence of the electrode material on the development with time of the reaction products was observed. Polymer-metal complexes with possible catalytic activity are formed on the surfaces of electrodes. From measurements it resulted that the discharge processes consist of simultaneously acting volume processes of plasmochemical nature (probably initiated by electrons) and electrocatalytic surface processes on electrodes (probably initiated by photons).

Thermally-stimulated spontaneous currents from metal-iodine doped polyvinyl pyrrolidone-metal system

A study of the spontaneous response currents from the metal-iodine doped polyvinyl pyrrolidone-metal (MPM) systems, on thermal stimulation at a constant rate, has been made with similar (Al-Al, Ag-Ag and Au-Au) and dissimilar (Al-Cu/Ag/Ni/PbZn) electrode systems. Thermograms of spontaneous current emission of iodine-doped PVP films exhibit two maxima around 90 ± 10°C and 130–160°C in the first heating run, whereas with the second heating run a single peak is found around 140–170°C. The magnitude and direction of current depend on the choice and combination of electrode materials. The position of the current peak in the thermal spectrum shifts with different heating run. A temperature dependence of open-circuit voltage (OCV) is also reported and it was found that OCV varied linearly with the difference in electrode work functions. The active centres of PVP are the carbonyl group of double-bond tertiary nitrogen atom (> N-C=O), and thus the charge transfer complexes are formed with iodine in PVP. The spontaneously-generated current is discussed in terms of weak complex formation with the water molecules and the liberation of different types of charges.