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The separator paper is a key component within a valve-regulated lead/acid (VRLA) battery. Here we describe an experimental program aimed at elucidating how separator papers influence battery performance. Identical batteries were manufactured using three different types of separator paper and subsequently cycled to failure. The failed batteries were then subjected to a series of tests, which included measurements of electrode potentials, compositional analysis of active materials, separator paper saturation and stratification measurements. Results indicated that separator paper type significantly influences battery performance. It is believed that subtle changes in the separator structure caused changes in the rate at which imbalances between the cells in each test battery developed, which led to subsequent changes in failure. [Copyright &y& Elsevier]

Abstract: This work provides an aging study of a graphite|LiNi1/3Mn1/3Co1/3O2 (NMC) Li-ion pouch cell with a nominal capacity of 10 Ah. By means of resistance and capacity measurements the cell's behavior is tracked over time under consideration of temperature and cell voltage impact. Tests duration was up to 15 months effective testing time. Observed effects and possible aging mechanisms are discussed considering the results from capacity and resistance measurements. The test results are used for a calendar lifetime prediction. In addition to a detailed calendar life study, also cycle life tests are discussed briefly to point out additional aging effects based on cycling. The paper may also serve as data source on aging for further work on battery lifetime modeling and battery diagnostics. Selected cells were taken from the aging tests and were used for a detailed post-mortem analysis (see paper “Part B: Post-Mortem Analysis”). [Copyright &y& Elsevier]

When charging a lithium-ion cell, the deposition of metallic lithium on the negative electrode surface, known as lithium plating, must be avoided. In this paper, the charging process of a commercial high energy lithium-ion pouch cell is investigated. Three-electrode test cells are assembled using electrode materials from the high energy lithium-ion pouch cell together with lithium metal as reference electrode to acquire the potential at the negative electrode-electrolyte interface. During charging, the cells' current is controlled in a way that the negative electrode potential is maintained constantly slightly above 0 V vs. Li/Li+. The resulting current map depending on temperature and state of charge is used to control the charging process of the pouch cell. Following this new charging procedure, a state of charge of 80% is reached in 15 min at 25°C ambient temperature. Different cycle life tests are performed to examine iteratively an approach to how the charging current has to be reduced over the lifetime in order to avoid accelerated aging. To prove the practicability, the method is tested at the battery pack level. • A temperature and state of charge dependent charging current map is recorded. • Charging time can be reduced significantly with new charging method. • Cycle life performance of the fast charging method is iteratively improved. • Higher lifetime compared to the reference method. • Validation of charging time at cell and battery pack level. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]

Conventional tetrabasic lead sulfate used as positive active material additive shows the results of the low effective lead dioxide conversion rate due to the large grain size and crossed the crystal structure. In this paper, we study on a type of nanometer tetrabasic lead sulfate. Through the XRD and SEM test and Material Studio software calculation, the purity of tetrabasic lead sulfate is very high, the grain size of the nanometer 4BS is almost unanimous, and can be controlled below 200 nm. When charged and discharged in 1.75 V–2.42 V with the current density of 40 mA g −1 , 80 mA g −1 and 160 mA g −1 , the effective lead dioxide conversion rate of nanometer 4BS after formation can achieve to 83.48%, 71.42%, and 66.96%. Subsequently, the nanometer 4BS as additive is added to positive paste of lead-acid battery. When the batteries are tested galvanostatically between 1.75 V and 2.42 V at 0.25 C charge and 0.5 C discharge rates at room temperature. The ratio of adding nanometer 4BS is 0%, 1% and 4% and the initial discharge specific capacities are 60 mAh g −1 , 65 mAh g −1 and 68 mAh g −1 . After 80 cycles, the initial discharge capacity of positive active material with 1% nanometer 4BS decreased less than 10%, while adding 4% nanometer 4BS, the initial discharge capacity doesn't decrease obviously. [ABSTRACT FROM AUTHOR]

Abstract: Reduction of the charging time for batteries is a crucial factor in the promotion of consumer interest in the commercialization of electric vehicles (EVs). Fast charging methods for EVs are therefore important to create and understand; however, fast charging is not tolerated by all lithium-ion chemistries because it typically affects the battery functionality and accelerates its aging mechanisms. A fast charging technique is proposed in this paper, and the results of extensive testing on a high power lithium iron phosphate cell subjected to the method are reported. The evaluation characterized the cell's capacity fade, cycle life, and energy efficiency with respect to the U.S. Advanced Battery Consortium (USABC) goals. The proposed charging algorithm permits a full recharging of the cell (0–100% SOC) in approximately 20 min, even after 4500 cycles are reached. The cycling scheme is characterized by high current discharges that reach specific powers of 400 W kg−1. The results show that the proposed fast charging technique does not introduce any significant degradation effects on the cell and is energy efficient; they also show that performance is lost due to capacity fade rather than an increase in internal resistance. [Copyright &y& Elsevier]

Abstract: In this communication, we disclose a proof-of-concept lithium/sulfur liquid battery that has exceptionally high capacity density. In such a battery, the cathode consists of a highly porous carbon cloth (CC) as the cathode current collector and a porous sulfur paper as the source of active material. In the first discharge, sulfur is reduced on the CC surface into high order lithium polysulfide (PS), which dissolves into liquid electrolyte and serves as the catholyte of the so-called “Li/S liquid battery”. By adopting a LiNO3-contained electrolyte to protect Li anode, the Li/S liquid cell is shown to cycle reversibly between 1.7 V and 2.8 V with an initial capacity of 778 mAh g−1 S, corresponding to a capacity density of 10.1 mAh cm−2 CC, which could be the highest capacity density among the rechargeable Li/S batteries reported ever. This work reveals that the high capacity density Li/S batteries can be made through a “Li/S liquid cell” by employing a highly porous carbon electrode to accommodate the insoluble sulfur reduction products (Li2S2/Li2S) with appropriate protection of the Li anode. [Copyright &y& Elsevier]

Abstract: The negative plates of lead-acid batteries subjected to partial-state-of-charge (PSOC) operation fail because of the development of an electrically inert film of lead sulfate on their surfaces. It has been found that carbon additives to the negative active material can significantly increase their cycle life in this type of operation. In this paper we show that various types of carbon, including graphite, carbon black eliminate the surface development of lead sulfate and that, in their presence, the lead sulfate becomes homogeneously distributed throughout the active material. Examination of active material by energy dispersive spectroscopy after extensive cycling shows that lead formed during charge of lead sulfate preferentially deposits on the carbon particles that have been embedded in the active material. Electrochemical studies have been carried out on a number of types of carbon additives having a wide range of properties. These included flake, expanded and synthetic graphite, isotropically graphitized carbon, carbon black and activated carbon. We have investigated their effect on the resistivity and surface areas of the negative active material and also on such electrochemical properties as active material utilization and cycle life. Most of the carbon additives increase the utilization of the active material and impressive increases in cycle life have been obtained with over 6000 capacity turnovers having been achieved. However, at this time, we have not been able to correlate either the type or the properties of the carbon with capacity or cycle life. Further work is needed in this area. The increases that have been achieved in cycle life provide evidence that the lead-acid battery is a viable low cost option for hybrid-electric vehicle use. [Copyright &y& Elsevier]

Abstract: Reliability assessment of lithium secondary batteries was mainly considered. Shape parameter (β) and scale parameter (η) were calculated from experimental data based on cycle life test. We also examined safety characteristics of lithium secondary batteries. As proposed by IEC 62133 (2002), we had performed all of the safety/abuse tests such as ‘mechanical abuse tests’, ‘environmental abuse tests’, ‘electrical abuse tests’. This paper describes the cycle life of lithium secondary batteries, FMEA (failure modes and effects analysis) and the safety/abuse tests we had performed. [Copyright &y& Elsevier]

Abstract: Future vehicle applications require the development of reliable and long life batteries operating under high-rate partial-state-of-charge (HRPSoC) working conditions. Work presented in this paper deals with the study of different design parameters, manufacturing process and charging conditions of spiral wound valve-regulated lead-acid (VRLA) batteries, in order to improve their reliability and cycle life for hybrid vehicle applications. Test results show that both electrolyte saturation and charge conditions have a strong effect on cycle life at HRPSoC performance, presumably because water loss finally accelerates battery failure, which is linked to irreversible sulphation in the upper part of the negative electrodes. By adding expanded graphite to the negative active mass formulation, increasing the electrolyte saturation degree (>95%) and controlling overcharge during regenerative braking periods (voltage limitation and occasional boosting) it is possible to achieve up to 220,000 cycles at 2.5% DOD, equivalent to 5500 capacity throughput. These results could make lead acid batteries a strong competitor for HEV applications versus other advanced systems such as Ni–MH or Li-ion batteries. [Copyright &y& Elsevier]

Abstract: In this paper, the effects of platinum addition on the structure and electrochemical properties of MgNiPt (Pt=1.0, 2.0 and 3.0at.%) metal hydride alloys are discussed. The ternary alloys were processed by mechanical alloying and had their structures characterized by X-ray diffraction, transmission electron microscopy and in situ X-ray absorption spectroscopy. It is observed that the structure of the alloys is formed by amorphous and nanocrystalline phases, with the size of the nano-grains close to 5nm. The electrochemical properties were evaluated by galvanostatic charge and discharge cycles using different discharge rates in the range of 10–80mAg−1. The best result was obtained for the Mg49.0Ni49.0Pt2.0 alloy, which showed smaller decay of the discharge capacity as a function of the charge/discharge cycle number, retaining 64% of its initial discharge capacity (364mAhg−1) after 10 cycles. [Copyright &y& Elsevier]

Abstract: This paper was focused on the development of prototypes for flat plate RAM™ (rechargeable alkaline manganese dioxide) cells. In contrast to cathodes used in cylindrical RAM™ cells, the mechanical stability is a significant issue for the preparation of flat plate cathodes. Therefore, the choice of an appropriate binder, e.g. Oppanol, is very important. In this work, an improved preparation process of flat plate RAM™ cathodes was developed by investigating the single steps of the preparation method. It was further demonstrated that the most critical factor of zinc electrode performance was the electrolyte content of the anode gel. Best overall cell performance was achieved at 40% zinc amount and a Zn/ZnO ratio of 5.0, in combination with an electrolyte content of 50.5%. In order to stabilise the γ-structure of manganese dioxide and to enhance rechargeability, the addition of barium compounds was also studied. Cell cycling has shown that flat plate RAM™ cells with BaSO4-modified cathodes outperformed control cells by 24%, mainly because of the minimised fade of discharge capacity. Moreover, the admixture of barium manganate to the cathode yielded more than 15% capacity improvement after 25 cycles, compared to the barium sulfate additive. [Copyright &y& Elsevier]

Abstract: The development of novel electrical systems for low emission vehicles demands batteries with specific cycling performance, especially under partial state of charge (PSOC) conditions. Moreover, according to the powertrain design, battery high power capability is demanded or this function can be assumed by a supercapacitor or a flywheel. This paper deals with the development of AGM and gel valve-regulated lead–acid batteries for advanced automotive applications. AGM VRLA battery development was based on previous work for short autonomy high power UPS applications and on active material formulations with specific additives to improve battery life under high rate partial state of charge cycling conditions. The 18Ah batteries showed excellent high rate capability (9kW 10s discharge peaks and 4kW 5s regenerative charge acceptance at 60% state of charge) and 110,000 power assist microcycles at 60% SOC and 2.5% DOD were fulfilled. Moreover, as preliminary work in the development of a cost-effective and reliable gel battery to be used in combination of a supercapacitor in a 42V mild-hybrid powertrain, VRLA batteries with conventional gel formulations have been tested according to novel automotive cycling profiles, mainly moderate cycling under partial state of charge conditions and simulating load management in a stop and start working profile. [Copyright &y& Elsevier]

The aim of the present paper was to study the influence of foam type as well as nickel and cobalt additives on cell performance and cycle life of cylindrical nickel–zinc cells. Experiments have shown that discharge capacity depends on the foam type of nickel electrodes and is significantly improved by using thicker foam substrates (2.2 mm). AA-size nickel–zinc cells constructed of two thinner nickel electrode layers (1.6 mm) displayed stronger decline in capacity during cycle life due to a very low zinc/nickel hydroxide ratio (1.1–1.2). The addition of nickel and cobalt powder was investigated by means of resistivity measurements of PVA-bonded nickel hydroxide films. This study elucidated that small amounts of cobalt (2–8 wt.%) caused an extreme decline in resistivity. Admixture of nickel also lowered resistivity but not as great as cobalt. The cell performance turned out to be contrary to resistivity measurements; nickel–zinc cells prepared with a less conductive slurry delivered higher capacities. However, discharge capacity decreased rapidly after prolonged cell cycling, as the zinc/nickel hydroxide ratio of these cells was also considerably reduced. [Copyright &y& Elsevier]

Organic expanders function in the negative electrode of lead–acid batteries to promote the development of fine crystal sponge lead upon formation and to preserve this high surface area structure by preventing coarsening of crystals upon cycling. Organic expanders also serve to protect the negative active material from passivation during discharge or on open circuit by preventing the formation of an impervious non-conducting film of lead sulfate. The deleterious effect of a high temperature service environment on the life of the lead–acid battery and the negative electrode is well known. In this paper, we investigate the effect of Vanisperse A organic expander content on the capacity and life of the negative electrode of flooded lead–acid SLI batteries designed to be negative electrode limiting. The low rate capacity and cold cranking performance of batteries designed to be negative electrode limiting remained essentially unchanged upon increasing the organic expander dosage from 0.25 to 0.50% on weight of lead oxide in a negative mixture. Battery life, however, when tested according to the SAE J240 protocol, increased 25% at 41 °C, and 20% at 75 °C. When tested according to the SAE J2185 protocol at 50 °C, battery life increased 15%. No adverse effects were observed. This work shows that increasing the Vanisperse content has a beneficial effect on the high temperature service life of the negative electrode. [Copyright &y& Elsevier]

Enabling fast charging of lithium-ion batteries may accelerate the commercial application of electric vehicles (EVs). The fast charging, however, could lead to capacity fade, lithium plating, and thermal runaway. This paper develops an optimal multi-stage charging protocol for lithium-ion batteries to minimize capacity fade due to the solid-electrolyte interphase (SEI) increase, to maximize the SEI potential to decrease the lithium plating, and to reduce the temperature rise to avoid a thermal runaway situation. An electrochemical-thermal-capacity fade coupled model is developed to monitor the battery internal state. The dynamic programming (DP) optimization algorithm is employed to search for the suboptimal charging current profiles. The optimization results illustrate that the optimized charging current profile varies with the state of charge (SOC) and the cycle number. As compared to the constant current charging protocol, each optimized charging strategy can reduce the capacity fade ratio by 4.6%, increase the SEI potential by 57%, and reduce the temperature rise by 16.3% for over 3300 charging-discharging cycles, respectively. • An electrochemical-thermal-capacity fade coupled battery model is developed. • A multi-stage fast charging protocol is proposed by dynamic programming with model. • Battery can be fast charged with low capacity fade. • Battery can be fast charged with a reasonable low temperature rise. [ABSTRACT FROM AUTHOR]