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We report on an effective approach to speed up the measurement of thermodynamic characterization curves (entropy of reaction ΔrS(x)) of rechargeable batteries, in particular commercial 18,650 lithium ion cells. We propose and demonstrate a measurement and data processing protocol that reduces the time required to record entropy profiles from time scales of weeks to time scales of hours - without loss in accuracy. For time consuming studies such as investigations on ageing of battery cells, entropy profile measurements thus become as feasible as conventional electrochemical characterisation techniques like dV/dQ or cyclic voltammetry. We demonstrate this at the examples of two ageing protocols applied to a commercial high power and a commercial high energy cell, respectively: (i) accelerated calendric aging by storing cells at 100% state of charge at 60 °C and (ii) continuous cycling with a 1 C current at 25 °C.

There is already a huge market for electric low-power light traction vehicles, mainly electric two wheelers (E2W) in the forms of E-bicycles and E-scooters. Such vehicles satisfy the demand for low-cost personal and load transportation with a concomitant reduction of environmental pollution in comparison with the two-stroke powered alternatives. Worldwide E2W annual sales in 2015 reached about 38 million units, of which China accounted for 33 million. The range of E2Ws is limited and is determined mainly by the battery. Nickel–cadmium, nickel–metal hydride, lead–acid and lithium-ion batteries have all been tested, but the vast majority of E2W batteries are either lead–acid or lithium-ion. The lead–acid batteries (LABs) are primarily of the absorptive glass-mat (AGM) design, although some gel types are used. The lithium-ion batteries (LIBs) are lithium iron phosphate (LFP); nickel, cobalt and aluminium (NCA) or lithium manganese oxide (LMO) types. LIBs have a much higher specific energy and thus provide higher range, but they have markedly higher costs. The LIB advantage of larger range and/or lower weight has led to a nearly 100% penetration of the E2W market by LIB in developed countries (Europe, Japan and the US). In China, however, the market is dominated by about 90% by LABs. A future shift from LABs to LIBs seems improbable for the mass market, given the cost premium relative to the performance advantages of LIBs.

This chapter compiles the advantages and challenges of present battery technologies, and outlines visions for future systems. The energy storage in conventional lead–acid and alkaline accumulators is compared with high-temperature batteries and progressive lithium-ion systems. The forcing development goal of 350 Wh kg−1 requires new battery concepts which seize cell voltages of 5 V and more. The state-of-the-art of experimental high-energy systems beyond lithium, such as metal-air, metal-ion, halide and redox flow batteries, is lucidly presented. Also supercapacitors and fuel cells are discussed. At present, alkaline and lithium-ion batteries control the market of battery electric vehicles.

The market share taken by different types of automobiles is likely to be substantially influenced by the contemporary legislation that governs fleet-average emissions of carbon dioxide (e.g., 95 g CO 2 km −1 in Europe by 2020). Functions, such as internal combustion engine start–stop, brake energy recuperation, propulsion-assist and pure electric drive, while reducing the CO 2 emissions will all increase the requirements to be met by the battery. In addition, there is much pressure to expand the electrical functionality of future automobiles in pursuit of greater safety and comfort. The challenges facing lead–acid batteries in meeting the energy storage demands of future generations of road vehicle are reviewed in this chapter.

To support the market introduction of fuel cells and hydrogen for energetic use in Germany, the National Innovation Programme Hydrogen and Fuel Cell Technology was set up in 2006. The German Federal Government together with representatives from research organisations as well as from various industry sectors were involved in designing the programme. Combined funds from the public and private sectors amount to Euro 1.4 billion and cover the period 2007–2016. About one-third of this total is to fund R&D and two-third to finance demonstration and market preparation projects. The National Organization Hydrogen and Fuel Cell Technology manages the implementation in close collaboration with its partner organisation Project Management Organization Julich, and in continuous consultation with the key stakeholders. This article spells out the main characteristics of the Innovation Programme and the organisations involved.

The paper describes, especially for EV applications, the requirements for the battery. In the focus are especially the car parameters (total car weight, driving behavior, temperature) and the battery parameters (discharge current, temperature, age), which are to be considered in order to estimate the available range. From the battery point of view important parameters are the state-of-charge (SOC) and the state-of-health (SOH). Advantages and disadvantages of SOC and SOH determination methods are discussed. But the priority of the requirements belongs to the safety of the car and the battery. The main risks, electrical, kinetic, chemical, and thermal, are addressed. Mainly the chemical and thermal risks and their safety relevant consequences are discussed. The thermal problems, which are leading to a thermal runaway with catastrophic consequences as fire or/and explosions, are highlighted. Furthermore, the energy of the cell is considered, which consists of the electrochemical energy (active masses) and the chemical energy (mainly combustion energy of the electrolyte). In case of a short circuit of the cell the electrochemical energy generates so much heat, that the chemical energy, i.e. the electrolyte, is autoignated at about 450°C. Thus, the electrochemical energy plays the role of a “lighter” and the chemical energy of combustibles.

In order for fuel cells to become a practical means of supplying power for road vehicles it will be necessary for a viable method of on-board hydrogen storage to be identified and implemented. Target values that must be achieved for the critical parameters in such a system have been drawn up by the US Department of Energy. It is quite clear that these targets cannot be met by systems that store hydrogen at high pressure or as a liquid at cryogenic temperatures. Attention has thus been focused on methods of storing hydrogen in, or on, a solid phase. In such schemes it is obviously desirable to make use of elements from the early part of the periodic table and there has been much interest in the possible use of carbon as a hydrogen host. This paper provides an overview of experimental work on such systems together with an outline of theoretical studies that have been undertaken to estimate the practical limits to the amount of hydrogen that could be stored per unit weight.

SnO2 was synthesized by precipitation from an aqueous solution of SnCl4 and NH4OH, followed by a heat treatment. The product was characterized by XRD, SEM, FTIR spectroscopy, DSC and TG. The XRD patterns suggest the formation of phase-pure cassiterite form of SnO2. SEM imaging indicates that the particles obtained are of sub-micron size with good morphology and size control (around ∼300 nm). Electrodes were fabricated by a slurry-coating procedure and the electrochemical performances of these electrodes were evaluated using galvanostatic cycling tests. The results suggest that the heat treated SnO2 samples deliver higher capacities when cycled between 1.0 and 0.1 V vs. Li+/Li and showed coulombic efficiencies of more than 98% in the tenth cycle.

A valve regulated battery (VRLA) with thin tubular electrodes combines the endurance of robust positive tubular electrodes and the enhanced power properties of very thin electrodes. Fast charging is essential for many applications and it can compensate the lower energy density of lead-acid batteries. Thin tubular electrodes VRLA batteries were cycle life tested and influences of two charging regimes were investigated. A comparison is made between a newly developed fast charging regime with current step-down and a conventional charging regime as regards battery life and performance. The fast charging procedure was beneficial for the cycle life; however, associated beneficial effects were reduced by certain drawbacks. A measuring method was developed for analysing the current distribution over the electrodes at high and low currents and results are presented in this paper. Post-mortem battery analyses were carried out to determine the dominating degradation effects. The differences in the degradation effects caused by the charging regimes are discussed. The paper concentrates on the newly developed fast charging regime and compares the influence of the charging regime on ageing mechanisms of the VRLA batteries with tubular electrodes as opposed to a conventional charging regime.

PEM fuel cells are viewed as one of the most environmentally friendly propulsion systems for automotive travel in the future. However, the PEM fuel cell is still too expensive for wide-spread commercialization. Besides the membrane electrode assembly, manufacturing of bipolar plates by milling from graphite or graphite composites is a very expensive process. In order to achieve cost reduction and at the same time meeting several technical requirements for mass production, a stack concept using graphite composite bipolar plates was developed. The tests reported in this paper show that the design goal of 10 kW could be significantly exceeded.

Investigations are presented to determine the dependence of the performance of direct methanol fuel cells (DMFCs) and the methanol cross-over rate on the operating conditions, on the structure of the electrodes and on the noble-metal loading. It is shown that performance and methanol permeation depend strongly on cell temperature and cathode air flow. Also, methanol permeation can be reduced significantly by varying the anode structure, but the changed electrode structure also leads to somewhat lower power densities. The metal loading is varied at the anode and cathode affecting the cell performance. Furthermore, the differences between supported and unsupported catalysts are compared. We discuss the optimum conditions for the DMFC operation considering the various important factors. The discussion is focussed on finding a compromise between fuel cell performance, fuel utilization and metal loading.

Batteries for stationary and automotive applications are required to provide extended cycle life and calendar life. Lithium–manganese oxides (LiMn2O4) with spinel structure and lithium–nickel–cobalt mixed oxides (LiNiCoO2) with layered structures have been extensively studied in the last few years for usage in high energy and high power batteries in order to replace lithium–cobalt oxide (LiCoO2) as cathode material in terms of cost, abundance and performance. In this paper, we summarize some basic mechanisms responsible for capacity fading under cycling and different storage conditions for both types of cathode materials. Lithium–nickel–cobalt mixed oxides show excellent storage stability in the discharged state and low metal solubility in the electrolyte. The cycling stability is mainly influenced by structural changes in the delithiated state and thermal instability arises from oxygen release at elevated temperatures in the charged state. Small amounts of aluminum and magnesium dopants stabilize the layered structure and increase cycling stability of lithium–nickel–cobalt oxide. Different mechanisms of capacity fading especially at higher temperatures are discussed for lithium–manganese oxide spinels. Capacity fading is highly dependent on cycling and storage conditions and caused by structural changes as well as by side reactions with electrolyte catalyzed by decomposition products of LiPF6 conducting salt and H2O impurities in the electrolyte.

The distributions of current and potential on the automotive positive plate have been studied. In the early stage of the discharge, the distributions of the current density, potential, and polarization resistance are uniform. In the later stage, however, the polarization resistance of the active mass increases very rapidly at the bottom and on the top of the plate. It causes the polarization to become very high and makes the current drop rapidly in these regions. It is also found that at the beginning of the 3 C discharge, the higher current density appears in the lower part rather than in the upper part of the plate, which is different from the conventional viewpoint. This may be due to the improper formation and overcharge of the plate.

The electrocatalytic activities of different binary Pt-Ru(ox) catalysts have been investigated in half-cell experiments by cyclic voltammetry and stationary current–potential measurements. The materials have been prepared using a modification of the Adams method. X-ray analytical methods (X-ray diffraction, XRD, and energy dispersive X-ray spectroscopy, EDX) as well as thermogravimetric analysis (TGA) have been used to characterize the composition and the catalysts' content of the crystalline phases, and their surface areas have been determined by the BET method. It is found that the composition of the catalyst is strongly influenced by the synthesis temperature, which is varied between 400 and 600 °C. In contrast, the particle size of the metallic phases of the catalysts is not significantly affected for synthesis temperatures below 600 °C, as investigated by transmission electron microscopy. Synthesis temperatures of ≥500 °C favor the formation of crystalline RuO2 phases, whereas at synthesis temperatures below 500 °C the presence of metallic alloy and of hydrous oxides was derived by the combined XRD and EDX measurements. The stationary current–potential curves show a correlation with the different synthesis temperatures. It can be concluded that both the presence of an alloyed metallic Pt-Ru phase as well as the presence of amorphous hydrated Ru oxides are favorable for the electrocatalytic oxidation of methanol.

Phase pure, homogeneous, and well-crystallized lithium iron phosphate LiFePO4 was synthesized by aqueous co-precipitation of an Fe(II) precursor material and succeeding heat treatment in nitrogen. The particle morphology of the precursor is preserved during the heat treatments. Excellent electrochemical properties in terms of capacity, reversibility, cycling stability and rate capability have been achieved. The thermal stability of charged electrodes is superior versus other positive electrode materials. If reductive synthesis conditions are used in the heat treatments, problems arise from the possible generation of iron phosphide.

This chapter provides a description of the working principles of the lead–acid battery (LAB) and its characteristic performance properties such as capacity, power, efficiency, self-discharge rate, and durability. Environmental and safety aspects are discussed, and it is made clear that the battery can be employed safely and sustainably as long as appropriate precautions are observed. A central theme of the chapter is a consideration of the diverse types of battery—starting, lighting, and ignition (SLI), enhanced flooded battery, and absorptive glass mat—that have been developed for different automotive applications such as SLI and stop–start operation in microhybrids. In this latter connection it has been recognized that the inclusion of carbon integrated into the negative plate of the battery in different ways can give rise to a huge improvement in performance. It is pointed out that batteries deploying the lead–acid chemistry in the microhybrid application have the lowest specific additional cost for the reduction of carbon dioxide emissions (€/% CO 2 reduction). An application of lead–acid in mild hybrids (12 V or even 48 V) would be possible if the dynamic charge acceptance and the total cycling throughput could be improved. The use of advanced LABs in dual systems with lithium-ion batteries would also be possible. Potential further improvements of the battery (e.g., through the use of optimized grids, bipolar designs, or additives) is discussed as is the use of LABs in engine downsize and boost concepts. A market forecast showing that in 2020 more than 50% of all cars will be microhybrids with LABs rounds off the chapter.

The first part of this chapter describes the expected evolution of the electric vehicles in the automobile market and the related production of the battery (mainly lithium) needed to power their electric engine. The content will be then addressed to the description and the evaluation of the processes presently in progress to recycle these batteries with particular attention to the economical, safe, and legislative aspects. These lithium battery recycling technologies are examined in terms of their operational steps, including sorting, separation, leaching, and thermal treatment. Also the historical aspect is here considered by describing a lithium battery recycling process proposed back in the year 2000 but still of actual relevance. Finally, the most recent developments are reported by discussing a recent European project aimed to the recycling of lithium and nickel metal hydride batteries with the recovery of their valuable parts.

The activity of unsupported ternary PtRuMeO x (Me=W, Mo, V) high surface area catalysts towards methanol oxidation under fuel cell relevant conditions, at constant potential and elevated temperature of 60 °C, was investigated by the thin-film electrode method. CO-stripping experiments for actual surface area detection, using differential electrochemical mass spectrometry (DEMS) to evaluate the amount of adsorbed CO, show that the electrochemically active area of the particle surface is significantly smaller than the total particle surface area determined by N 2 BET measurements, indicating that part of their surface consists of MeO x . The specific surface activity of the catalysts towards methanol oxidation at 60 °C, normalized to the current density per square centimeter of electrochemically active noble metal surface, decreases in the order PtRuVO x >PtRuMoO x >PtRu>PtRuWO x =PtRu (E-TEK). Apparently, the surface oxide leads to an acceleration of the methanol oxidation reaction, which is, however, partly compensated by a decrease in active surface area.

Finely dispersed Pt- and Pt/Ru-particles have been deposited on high surface-area ruthenium dioxide (RuO2) using the Petrow and Allen method [U.S. Patent No. 4,044,193 (23 August 1977)]. RuO2 has been synthesized according to different preparation methods. It turned out that the product showing the highest surface area could be produced by a simple fast precipitation method. The electrocatalytic activities of catalysts on different ruthenium oxide supports have been investigated in half-cell experiments by stationary current voltage measurements. Pt/Ru-catalysts deposited on a Vulcan XC-72 carbon black have been used for comparison. X-ray analysis methods (XRD, EDX) have been used to characterize the composition and crystallinity of the materials and their geometric surface areas have been determined by the BET method. It turned out that the electric conductivity of the RuO2 materials was comparable to that observed for Vulcan XC-72. Furthermore, RuO2 materials having a BET surface area above 125 m2/g could be synthesized. (Vulcan XC-71: ∼250 m2/g). Surprisingly, no significant electrochemical activity was found when Pt/Ru was deposited on freshly precipitated hydrous RuO2. Deposition of noble metals on calcined RuO2 resulted in electrochemical activities comparable to the ones obtained for the Vulcan XC-72 support. Thus, no extraordinary enhancement of catalytic activity for the methanol has been observed when RuO2 oxide was used as a mixed conducting catalyst support.

The compression of gases in conventional compressors is often combined with low efficiency and the contamination of the compressed gases. In this paper, a system is described that uses an electrochemical cell for the compression of hydrogen. This electrochemical hydrogen compressor operates at lower hydrogen flux than mechanical hydrogen compressors. Further development of polymer electrolyte membrane (PEM) fuel cells afford a good prospect of realizing the electrochemical compression on a competitive basis. A specialized gas diffusion layer established the possibility to pressurize the cathode volume up to 54 bar. The ohmic resistance and pressure stability have been rescued by an improved membrane electrode assembly (MEA). A three cell stack on a laboratory scale has been designed. Data of single cell and stack experiments will be discussed in this paper. The advantages of the electrochemical system, apart from the efficiency, are: noiseless operation, purified hydrogen and simplicity of the system cooling.

The performance of direct methanol fuel cells (DMFC) is limited by the cross-over of methanol through the electrolyte. Electrolyte membranes prepared by blending of sulfonated arylene main-chain polymers like sulfonated PEEK Victrex (sPEEK) or sulfonated PSU Udel (sPSU) with basic polymers like poly(4-vinylpyridine) (P4VP) or polybenzimidazole (PBI) show excellent chemical and thermal stability, good proton-conductivity, and good performance in H2 PEM fuel cells. Furthermore, these materials have potentially lower methanol cross-over when compared to standard Nafion-type membranes. In this work, membrane electrode assemblies (MEAs) have been prepared from such membranes according to the thin-film method. The catalyst layer was spray-coated directly on the heated membrane using an ink consisting of an aqueous suspension of catalyst powder and Nafion solution. Unsupported catalysts were used for anode and cathode. A rather high catalyst loading was chosen in order to minimize the effects of limited catalyst utilization due to flooding conditions at both electrodes.

Ruthenates based on SrRuO 3 perovskite exhibit pseudocapacitance behavior. Replacing up to 20 mol% Sr by La leads to an increase of the specific capacity. The stability window of ruthenates is strongly dependent on B-site cations. Fe or Co substitution reduces the stability of the electrolyte whereas 20 mol% doping by Mn on the B-site increases the capacity without reducing the potential window. A capacitance up to 270 F/g was obtained by optimizing composition and preparation route. Cobalt or aluminum mixed hydroxides/oxyhydroxides also seems to have the potential for high pseudocapacitance behavior and exhibit capacitance up to 360 F/g, but the potential window is very limited.

The electrocatalytic activities of different ternary platinum–ruthenium (Pt–Ru)–metal-oxides have been investigated in half cell experiments, by cyclic voltammetry and stationary current–voltage measurements. The results are compared to binary Pt–Ru alloy catalysts. The materials have been prepared using a modification of the Adams method. X-ray analytical methods (X-ray diffraction, XRD; energy dispersive X-ray spectroscopy, EDX; X-ray photoelectron spectroscopy, XPS) have been used to characterize the composition, particle size and crystallinity of the catalysts, and their surface areas have been determined by the Brunauer–Emmet–Teller (BET) method. The catalyst materials consist of varying amounts of metal oxides and Pt–Ru alloy particles. BET surface areas of 80–120 m 2 /g have been measured corresponding to particle diameters of the order of 3–5 nm. The results of electrochemical measurements demonstrate that introduction of a transition metal oxide (WO x , MoO x , VO x ) leads to an improvement of the catalytic activity towards methanol oxidation.

Studies are focused on the hydrogen adsorption on carbon materials at ambient temperature. The hydrogen adsorption from the gas phase was measured by isothermal gravimetric analysis, using a microbalance at hydrogen pressures up to 125 bar at 23°C. In this work, the hydrogen adsorption reached values of approximately 1.5 wt.% at ambient temperature and 125 bar.

Advanced batteries, like lithium-ion batteries, are more sensitive in case of irregular operation than conventional batteries. Therefore, the operation of such batteries must be controlled by a management system. The features of a battery management system depend on the application, but in most cases, features like battery state determination, electrical management and safety management are necessary. This paper describes these functions of a battery management system. The use of a battery management system will lead to an increased lifetime and a safer operation of the battery.

In order to develop electric vehicles (EVs), electrochemical scientists and engineers have paid great attention to the study of batteries in recent years. Now, while new types of batteries are still in development, the valve-regulated lead-acid (VRLA) battery is a near-term candidate for EV applications in mass markets. The recharge time for valve-regulated lead-acid batteries has been reduced and is now less than 5, 15, and 240 min for 50, 80, and 100% charge. However, many other problems arise from pulse charging such as reduced cycle life of the battery, corrosion of the positive-electrode grid, loss of electrolyte, and thermal management. The kinetic processes of both PbSO{sub 4} oxidation and the oxygen evolution reactions were studied under pulse charging conditions. Three kinds of diffusion processes appeared in the positive active mass. The time intervals required to relax the respective concentration polarizations were about 0.1, 300, and more than 10,000 s. At the beginning of the pulse charge, the passivation layer formed between the grid and active mass at the positive plates exhibited a poor electronic conductivity and impeded the diffusion of O atoms. Thus, the electrode polarization increased and oxygen evolution accelerated. Following the initial pulse, the diffusion of Omore » atoms became rapid while the concentration of ions such as HSO{sub 4}{sup {minus}} and SO{sub 4}{sup 2{minus}} at the reaction surface increased gradually so that their diffusion became dominant in the solution near the reaction surface. For longer times, the charge rate was controlled by the diffusion of these ions in the micropores of the active mass. The electrode polarization, oxygen evolution, and loss of water can be inhibited by using a pulse discharge or/and prolonging the off-time of pulse charge.« less

Strontium ruthenate SrRuO 3 is a well functioning member of the family of metallic conducting oxides with the perovskite type structure. Its properties relevant to electrochemical capacitors depend on the conditions of synthesis as well as on the nature and amount of dopants. Undoped SrRuO 3 prepared by a coprecipitation process exhibits capacitances of about 10 F g −1 . Replacing the B cation Sr by Fe or Co does not influence the capacitance but decreases the stability window of the KOH electrolyte. Mn doping however as well as La doping on the A-site increases the capacitance to values of 20–30 F g −1 . A model of the charge storage mechanism is given and discussed. It involves protonic conduction via the Grotthus mechanism inside the perovskite structure. A new synthesis technique based on pyrolysis of a salt solution is introduced which yields ten times larger specific capacitances.

A study is made of the influence of different operating conditions (i.e., cycling, self-discharge, floating) on the lifetime of different types of lead/acid battery (vented: flat plate, tubular; valve-regulated: gel, AGM) recommended by manufacturers for solar applications. A bench test has been conducted for more than six years and is based on practical photovoltaic operating conditions. The best performance is exhibited by gel batteries and by vented, pasted-plate batteries with electrolyte agitation. The over-discharge of series-connected cells in large solar battery packs influences the lifetime. Results are given for the discharge and over-discharge characteristics of lead/acid batteries, i.e., battery voltage, cell voltage, positive and negative electrode potentials, gassing rate, oxygen evolution, and sulfuric acid density. The same characteristics are also examined for the recharge of over-discharged batteries. In the over-discharge period, inactive PbO2 and Pb are activated and can react in a further electrochemical discharge or/and in a chemical comproportionation reaction.

The influence of the active mass, as well as of discontinuous polarization (100 h at 6 mA cm−2, 68 h at open circuit) on the corrosion rate of lead-antimony alloys has been measured with respect to samples without active mass and continuous polarization. During continuous polarizations two time regions have been found for the corrosion rate (v): during the first 75 h, the corrosion rate decreases according to v ∼ 1 t 0.5 and then is constant during the remaining second period. An active-mass protection factor (PFAM) describes the decrease of the corrosion rate in the presence of active mass; PFAM is > 2. Surprisingly, such a protection factor is also found in the presence of electronically isolating α-Al2O3. The influence of changes in potential, current density, pH and corrosion structure on the corrosion rate in the presence of active mass is discussed. The main influence comes from changes in the corrosion structure. A model is developed on the basis of diffusion of oxygen species through a dense corrosion layer. This corrosion layer grows to a critical thickness. After reaching this critical thickness, the layer divides into a inner dense and an outer porous zone as a result of relaxation in the internal mechanical stress that is created by the higher volume of the corrosion product. This model explains the time course of the corrosion rate, the action of the active mass and the influence of rest periods during polarization.

Previously, premature capacity loss (PCL) has been generally interpreted as a discharge inhibition of the positive electrode. PCL has been primarily explained by changes in the structure and the properties of the grid/corrosion-layer interface, changes in the solid-state properties of non-stoichiometric PbO 2 in the active mass (e.g., as an increase in the electrical resistance of the particle necks), or by means of a decrease in the conductivity of gel zones in the positive plate (gel—crystal model). A special phenomenon of anitmony-dependent PCL is observed under constant-voltage charging (CVC) and (subsequent) acid stratification. This effect termed as CVC—PCL differs from the original PCL phenomenom. This is because it is identified as a polorization phenomenom at the active-mass/electrolyte interface. CVC—PCL is characterized by inhomogeneous sulfation that commences in the lower regions of the electrode with residual lead sulfate increasingly remaining in the charged state. As with PCL, CVC—PCl phenomena are not caused by an antimony deficit. However, the phenomena are substantially suppressed in the presence of antimony.

Strontium ruthenate SrRuO 3 is a well functioning member of the family of metallic conducting oxides with the perovskite type structure. Its properties relevant to electrochemical capacitors depend on the conditions of synthesis as well as on the nature and amount of dopants. Undoped SrRuO 3 prepared by a coprecipitation process exhibits capacitances of about 10 F g −1 . Replacing the B cation Sr by Fe or Co does not influence the capacitance but decreases the stability window of the KOH electrolyte. Mn doping however as well as La doping on the A-site increases the capacitance to values of 20–30 F g −1 . A model of the charge storage mechanism is given and discussed. It involves protonic conduction via the Grotthus mechanism inside the perovskite structure. A new synthesis technique based on pyrolysis of a salt solution is introduced which yields ten times larger specific capacitances.

Passivation caused by sulfate formation within corrosion layers during cyclic deep discharge of PbO 2 electrodes with grids free of antimony can be diminished by addition of phosphoric acid to the electrolyte. The mechanism was studied by means of cyclovoltammetric and potential-step measurements, X-ray diffraction and scanner electron microscopy (SEM). It was observed that phosphate ions adsorbed specifically on lead dioxide influence nucleation and nuclei growth of PbO 2 . During discharge of PbO 2 formed in this manner a PbSO 4 of extremely fine grain and dense structure was found, which protects PbO 2 against further discharge and thus prevents an irreversible sulfation of the corrosion layer.

The Workshop was organized by the Dresden University of Technology. The leaders of the organizing committee were K. Wiesener and J. Garche. The meeting brought together 48 scientific and industrial experts from 16 countries to define and assess the major problems that presently limit further development of the lead/acid system. In particular, support from the UNESCO Regional Office of Science and Technology for Europe and North America (ROSTENA) and from VARTA, GRACE, DETA, BOSCH, DIGATRON and Zwickauer Batterie GmbH allowed delegates from both the east and west to join together in open debate in the pleasant environment of Gaussig Castle near Dresden. The scientific programme was divided into three main topics of special interest: modes of battery failure, reactions at the grid/active-material interface, problems with valve-regulated ‘sealed’ lead/acid batteries, and into two further topics of general interest: modern measurement methods, modern technology and new materials.

The addition of phosphoric acid to the electrolyte or the positive active material of the lead/acid battery yields different results. For antimony-free batteries, the capacity is reduced but the lifetime is improved under deep-discharge service. Both effects at the positive electrode appear to originate from the same cause, namely, the crystal size of PbSO 4 is decreased considerably in the presence of phosphoric acid. The utilization of the positive active material is reduced because the resulting fine-grained PbSO 4 covers the PbO 2 . On the other hand, the PbSO 4 protects the corrosion layer against further discharge. The action of phosphoric acid is demonstrated through cyclic voltammetric, potential-step, impedance and microscopic investigations.

For characterizing the oxygen cycle in sealed lead-acid batteries the technological terms “oxygen recombination efficiency” and “oxygen recombination conditions” are introduced and their different meanings explained. Numerical values are calculated or estimated from plots of overpressure against time. Emphasis is placed on investigations of the influence of technological parameters on oxygen recombination conditions.

Publisher Summary This chapter discusses the application and benefits of large-scale battery energy-storage systems (BESS) in electricity power-supply networks. The great majority of systems deployed have been BESS designs based on lead–acid technology. Computer-based, power-electronic control systems are creating a growing demand for reliable, high-quality electrical power that can be available via energy storage systems. This trend favours a growing number of BESS applications. Most BESS applications require the four-quadrant operation that is the ability of the ac side to both absorb and deliver both volt-ampere reactive (VAR) and watt. This capacity is provided by the back diodes that parallel the power switches and controls on the firing angles of the power switches. Many electric utility companies world over are successfully using BSESs for power supply. Crescent Electric Membership Corporation, Statesville, NC, the United States is using a 500 kW, 500 kWh BESS as a peak-shaving facility since July 1987 to reduce demand charges paid to their supplying utility. The battery consists of a single string of 324 cells configured six cells per module. These are flooded, deep-cycle cells with lead–antimony grids. The BESS at the GNB lead smelting and recycling center in Vernon is foremost an uninterruptable power supply (UPS) system that serves an essential purpose at an environmentally sensitive facility. The recycling centre is located about 16km south-east of downtown Los Angeles, and it recycles about ten million lead–acid batteries annually. The PQ2000 is another BESS that is designed to meet the growing market demand for high quality, reliable power for industrial and utility applications. It is primarily a rapid reserve resource that temporarily substitutes for the utility supply in the event of a power-line anomaly and, subsequently, returns the load to utility service excitation when the service returns to normal.

The authors have tested, for about 6 years, four different types of lead-acid batteries under cycling, floating and self-discharge conditions. A correlation has been established between the operating data (current, voltage) and the capacity measured during these tests by a fuzzy cluster approach. The data sets were categorised in three fuzzy clusters. These three fuzzy clusters: (1) starting phase (new phase); (2) working phase; and (3) capacity drop phase should able to describe the ageing behaviour of the battery sufficiently. For all fuzzy analysed data, they found a continuous correlation between the fuzzy classifications and the operation time of the battery, which themselves correlate to the development of the battery state of health. This fuzzy technique allows the prediction of the future behaviour of the battery by measuring the operating parameters (current, voltage) without explicitly checking the capacity, if the fuzzy set is determined once as a kind of calibration curve.

Reliability and costs of an energy storage system are two very important parameters for uninterruptible power supplies (UPS) and other battery applications. The increasing of battery life and the prediction of battery failure are therefore two important features of a battery management system (BMS). A couple of other helpful features can be implemented in a BMS. In the case of advanced batteries, special features like thermal management (i.e. high temperature batteries) or safety management (i.e. lithium batteries) is necessary. Therefore the BMS must be optimized to the battery type and the application. In smaller systems the BMS is connected very closely to the battery or inside the battery and an operation without the BMS is not possible.

In order top reduce C02 emissions world-wide, more efficient energy technologies are required in the future. Combined heat and power generation has a considerable higher fuel efficiency than conventional technologies. Today, mostly internal combustion engines are used for this purpose. The use of fuel cells will introduce further benefits due to their higher electrical efficiency and their negligible emissions of other pollutants.

Strontium ruthenates with the perovskite type structure ABO3 have been shown to exhibit attractive capacitive properties. Doping on the A site with La lead to typical capacitance values of 21 F/g. These materials were synthesized by coprecipitating metal hydroxides from a stoichiometric salt solution and subsequent firing at 800 °C in air. In this paper we present a new procedure to synthesize the materials which are crystalline and nevertheless show appreciable capacitances in contrast to ruthenium dioxide material, which only works in a hydrated amorphous structure. The process basically consists in a pyrolysis of concentrated metal salt solutions of the respective chlorides and nitrates at 500 °C for several minutes. Excess soluble phases are removed by washing out with water. X-ray diffraction experiments revealed similar phase purity and crystallinity as known from the coprecipitated materials. However the measured capacitances of undoped perovskites reached high values of 200 F/g exceeding twenty times the value of respective coprecipitated materials. First experiments on doping the materials promise further progress. The new synthesis route introduces a higher surface area by leaving cavities from leached soluble phases and bulk defects into the crystal structure. The first effect increases the number of active sites in contact with the electrolyte while the latter enhances the protonie conduction which is necessary to keep the charge balance within the material during cycling.

The specific energy of modern rechargeable alkaline batteries (e.g. Ni-metal hydride) is meanwhile determined by the capacity and the weight of the positive electrode. One possible way to increase the specific energy of these batteries is to replace the positive electrode by an “air breathing” electrode. Thus, systems with high specific energy can be achieved by e.g. primary metal — air batteries or fuel cells. In practical energy storage applications however, it is desirable to design an electrically rechargeable energy storage system. Therefore, bifunctional air electrodes are the key components for “air breathing” electrochemical energy storage systems such as: metal — air batteries (e.g. Zn — air, Fe — air) reversible hydrogen — air fuel cells metal — hydride — air storage systems

Energy is existing in various forms, e.g. elecrical (EE), chemical (CE), heat (HE), radiation (RE). There are many routes to convert energy from one form into another. These energy converters are generally of different kind. A typical converter system can be an electrochemical cell.