High Charge Acceptance Research Articles

Performance benchmark of state-of-the-art high-power lithium-ion cells and implications for their usability in low-voltage applications

For vehicle electrical systems, high-power optimized lithium-ion batteries offer superior cycle stability, compactness and weight compared to conventional lead–acid batteries. To identify lithium-ion cell candidates during early concept and development phases, both performance characteristics and a comparison of commercialized lithium-ion cells covering different cell chemistries are needed. Since the market share of high-power lithium ion cells is limited, scientific studies and extensive characterizations are rare. This study closes the gap by benchmarking state-of-the-art high-power cells considering the requirements of 12V/48V applications. The sensible begin-of-life parameters OCV, internal resistance, and capacity were investigated by stepwise OCV measurement, pulse power characterization and capacity measurement regarding the dimensions: SOC (0% to 100%), temperature (−25°C to +55°C) and current rate (up to 30C). All cells exhibit temperature dependent OCV curves, with ambient temperatures above zero hardly affecting the OCV hysteresis. A SOC dependency of the internal resistance of the tested lithium titanate oxide cell reduces the power capability, available cell capacity and energy efficiency. This cell, in contrast to the graphite-based cells, enables a neglection of a Butler–Volmer dependency and offers high charge acceptance at negative temperatures. The internal resistance of the lithium iron phosphate cell is less affected by SOC which allows for constant power output. Above 25°C and up to 15C, energy efficiencies of the graphite-based cells exceed 95%. We conclude that the lithium iron phosphate cell is best suited for 12V applications due to its voltage band and discharge characteristics. None of the cells stand out for use in 48V applications. Our findings from benchmarking among different cell chemistries are beneficial to other research areas such as battery simulation, battery management systems, or cell/system design.

High charge acceptance through interface reaction on carbon coated negative electrode for advanced lead-carbon battery system

In this research, the interfacial effect between the carbon layer and the negative electrode surface is evaluated as a hybrid electrode with higher charge acceptance for the advanced lead-carbon battery (ALC-battery) system. The P-60 (activated carbon) material, with high specific surface area (1787 m2 g−1) and higher electrical conductivity (98.85 S cm−1), is considered an efficient activated carbon in the present investigations and deposited on the negative electrode. Compared to the conventional lead-acid battery system, the carbon coated negative electrode of ALC-battery system exhibited higher capacity at the applied higher charge/discharge current. The efficient performance of the ALC-battery is mainly influenced by the thin layer of carbon on the active electrode surface, which induces higher charge acceptance. Furthermore, the ALC-battery showed an outstanding lifespan performance compared to the conventional lead-acid battery system in long-term operations. The resulting cycle life stability of lead-acid battery and ALC-battery is 2230 and 6780 cycles, respectively. The significant performance of the ALC-battery is mainly attributed by synergistic mechanism in hybrid electrode, which is resulted from interfacial effect. The likely synergetic reactions arises by carbon layer is (i) higher charge acceptance, (ii) controlled the formation of PbSO4 crystallite in the electrode surfaces, (iii) improved electrochemical performances and Pb redox reaction due to higher electrical conductivity properties. Thus, it can be concluded that the carbon layer deposited on the negative electrode in the ALC-battery is an efficient approach for energy storage, with increased power, capacity, and enhanced cycle life stability.

Preparation and characterization of Pb nanoparticles on mesoporous carbon nanostructure for advanced lead-acid battery applications

To enhance the electrochemical energy performance, the lead nanoparticles on mesoporous carbon (Pb on MPC) were prepared and characterized for advanced lead acid battery (Ad-LAB) applications. At present, Ad-LAB garners significant attention in energy storage devices because of its high charge acceptance. However, the major problem has associated with the large crystallization of PbSO4 in negative electrode during unit cell operation. To minimize this issue, Pb nanoparticles have incorporated on MPC in this present investigation. The Pb on MPC has prepared through facile chemical reduction process. The structural analysis of Pb, MPC, and Pb on MPC have confirmed by X-ray diffraction analysis. The specific surface area (SSA) and pore size distribution of MPC and Pb on MPC has obtained through Brunauer-Emmett-Teller measurements. The obtained SSA is 245.38 and 32.42 m2 g−1 for MPC and Pb on MPC, respectively. Additionally, the incorporation of Pb on MPC has confirmed by the microstructural analysis of high resolution transmission electron microscopy. The obtained particle sizes of the Pb nanoparticles are ~5 nm. Based on the structural, microstructural and cyclic voltammetry analysis, we suggest that Pb on MPC can be used as an efficient active material for negative electrode in Ad-LAB systems.

Influence of H 2SO 4 concentration on the performance of lead-acid battery negative plates

The influence of sulfuric acid concentration on negative plate performance has been studied on 12 V/32 Ah lead-acid batteries with three negative and four positive plates per cell, i.e. the negative active material limits battery capacity. Initial capacity tests, including C20 capacity, cold cranking ability and Peukert tests, have been carried out in a wide range of sulfuric acid concentrations (from 1.18 to 1.33 sp.gr.). High initial capacity and good CCA performance were registered for batteries with acid concentration between 1.24 and 1.30 sp.gr. The charge acceptance depends on acid concentration as well as on battery state of charge. Batteries with high SoC exhibit high charge acceptance at low acid concentrations. The cycle life tests at two discharge rates (10 and 3 h discharge) evidence that sulfuric acid concentration exerts a strong effect on negative plate performance. The cycle life of batteries decreases with increase of acid concentration. The obtained results demonstrate the high impact of lead sulfate solubility on the cycle life and charge efficiency of lead-acid batteries.

Effects of Dynamic Electrodes on Sodium Sulfur Cell Performance

The construction and performance of a sodium sulfur cell with dynamic sodium and sulfur electrodes are described. The cell was constructed with a sodium feed into a β″‐alumina tube and a sulfur feed into an annular sulfur electrode. Low‐resistance graphite felt was tightly packed around the β″‐alumina tube. Sodium pentasulfide was removed from the sulfur electrode. The cell was stably charged in the two‐phase region and a high charge acceptance of 95% was obtained. The cell capacity and the discharge voltage increased with the sulfur and sodium feeds. The internal resistance was decreased by thinning the sulfur electrode and using a single zone of low‐resistance graphite felt.

Studies on electrothermographic behaviour of poly(styrene‐co‐allyl alcohol) and leucomalachite green mixed system

AbstractThe electrothermographic behaviour of poly(styrene‐co‐allyl alcohol) sensitized with different amounts of leucomalachite green has been studied. The following parameters were investigated: maximum acceptance potential, surface potential decay at room temperature and under infrared irradiation, contrast potential, residual potential, and thermosensitivity. Pure as well as sensitized layers show quite high charge acceptance on corona charging. Addition of the thermosensitizer causes an enhanced contrast potential at constant IR exposure.

Electrothermographic behaviour of poly (acrylonitrile butadiene styrene) and leucomalachite green mixed system

The electrothermographic behaviour of poly (acrylonitrile butadiene styrene) (ABS) pure as well as sensitized with different weight percentages of leucomalachite green, (LMG) has been studied. The following important parameters were investigated: (i) maximum acceptance potential; (ii) surface potential decay at room temperature and under exposure to infrared (IR); (iii) contrast potential (i.e. difference in surface potential of areas maintained at room temperature and of areas exposed to infrared); (iv) thermosensitivity (i.e. rate of decay of electrical potential when plate is exposed to infrared); and (v) retentivity as determined by rate of decay of electrical potential at room temperature.A solution cast layer of ABS on aluminum substrate shows very high charge acceptance on corona charging. Addition of a thermosensitizer (LMG) in the polymer matrix shows enhanced contrast potential at constant IR exposure. The thermosensitivity of ABS increases considerably with the addition of leucomalachite green. Optimum conditions for the suitability of the polymer in electrothermography is determined by studies on different weight proportions of sensitizer. Corresponding carrier mobilities are calculated from surface potential decay characteristics at room temperature.

Electrothermographic characteristics of poly(styrene-allyl alcohol)

The paper describes electrothermographic characteristics of poly(styrene-allyl alcohol) such as charge acceptance, decay of charge at room temperature and under infrared exposure, contrast potential, residual potential and fatigue effect. The polymer layer (65 μm thick) is found to have high charge acceptance: initial surface charge density is 5.72×10−4 Coulomb/m2, long retentivity of charge at room temperature (28% decay in 500s) and maximum contrast potential of 1300V at 70°C. The high charge acceptance of the polymer has been related to the presence of phenyl and hydroxyl groups in the polymer structure which form traps of depth 1.2eV. The decay of surface potential is in the temperature range 50–70°C and is related to the glass-rubber transition of the polymer at 58°C.

Study of surface potential characteristics of corona charged ethyl cellulose layers for its relevance in electrothermography

AbstractA solution cast layer of ethyl cellulose on aluminium substrate shows high charge acceptance on corona charging. Its surface potential decay characteristics are studied at room temperature and at higher temperatures. Addition of a thermosensitive dye in the polymer matrix shows enhanced contrast potential at constant IR exposure. Optimum conditions for suitability of the polymer in electrothermography is determined by studies on different weight proportions of dye. The effect of layer thickness on surface potential characteristics is also investigated.