Thermal Characterizations of a Lithium Titanate Oxide-Based Lithium-Ion Battery Focused on Random and Periodic Charge-Discharge Pulses

Thermal characterization of lithium-ion batteries is essential to improve an efficient thermal management system for lithium-ion batteries. Besides, it is needed for safe and optimum application. The investigated lithium-ion battery in the present research is a commercially available lithium titanate oxide-based lithium-ion battery, which can be used in different applications. Different experimental facilities were used to measure lithium-ion battery heat generation at different operating conditions and charge and discharge rates in this investigation. Isothermal battery calorimeter is the exclusive calorimeter globally, suitable for lithium-ion batteries’ accurate thermal measurements. Pulse charge and discharge in different increments of state of charge were applied to the lithium titanate oxide-based lithium-ion battery to designate the heat generation of the lithium-ion battery cell. Three different cases were studied. The precise effects of different state-of-charge levels and current-rates on lithium-ion battery total generated heat was investigated. The maximum heat generation during 13 A, 40 A, 50 A, 60 A and 100 A pulse discharges were 0.231 Wh, 0.77 Wh, 0.507 Wh, 0.590 Wh and 1.13 Wh correspondingly. It could be inferred that in the case of periodic charge and discharge pulses applied to the lithium titanate oxide-based lithium-ion battery, important parameters including state of charge, current rates, initial cycling, and temperature have a significant influence on total generated heat.

Add-On Type Pulse Charger for Quick Charging Li-Ion Batteries

In this paper, an add-on type pulse charger is proposed to shorten the charging time of a lithium ion battery. To evaluate the performance of the proposed pulse charge method, an add-on type pulse charger prototype is designed and implemented. Pulse charging is applied to 18650 cylindrical lithium ion battery packs with 10 series and 2 parallel structures. The proposed pulse charger is controlled by pulse duty, frequency and magnitude. Various experimental conditions are applied to optimize the charging parameters of the pulse charging technique. Battery charging data are analyzed according to the current magnitude and duty at 500 Hz and 1000 Hz and 2000 Hz frequency conditions. The proposed system is similar to the charging speed of the constant current method under new battery conditions. However, it was confirmed that as the battery performance is degraded, the charging speed due to pulse charging increases. Thus, in applications where battery charging/discharging occurs frequently, the proposed pulse charger has the advantage of fast charging in the long run over conventional constant current (CC) chargers.

Improved Performance of Li-ion Polymer Batteries Through Improved Pulse Charging Algorithm

Pulse charging of lithium-ion polymer batteries (LiPo), when properly implemented, offers increased battery charge and energy efficiencies and improved safety for electronic device consumers. Investigations of the combined impact of pulse charge duty cycle and frequency of the pulse charge current on the performance of lithium-ion polymer (LiPo) batteries used the Taguchi orthogonal arrays (OA) to identify optimal and robust pulse charging parameters that maximize battery charge and energy efficiencies while decreasing charge time. These were confirmed by direct comparison with the commonly applied benchmark constant current-constant voltage (CC–CV) charging method. The operation of a pulse charger using identified optimal parameters resulted in charge time reduction by 49% and increased charge and energy efficiencies of 2% and 12% respectively. Furthermore, when pulse charge current factors, such as frequency and duty cycle were considered, it was found that the duty cycle of the pulse charge current had the most impact on the cycle life of the LiPo battery and that the cycle life could be increased by as much as 100 cycles. Finally, the charging temperature was found to have the most statistically significant impact on the temporarily evolving LiPo battery impedance, a measure of its degradation.

Accelerated Model of Charging of Lead­Acid Batteries. 4. Pulse Charge with Asymmetrical Current, Gas Evolving and Service Life

This paper is the conclusion to the series of the articles devoted to the problem of accelerated charging of a lead­acid battery. In this paper we investigated the possibility of increasing the charge efficiency by applying the asymmetric current at the second stage. In addition, the effect of using admissible charging rates on the resource, the admissible number of consecutive cycles, and gas release were studied.

A Study of Fast Charging of Li-Ion Battery With Pulsed Current

To fast charge lithium ion batteries while achieving higher capacity and limiting temperature rise, a constant current plus pulse current (CCPC) charging protocol is proposed. Parametric study for the CCPC design parameters including the current level, cut-off voltage, and pulse duration is performed experimentally. Taguchi method is adopted to search an optimal charging pattern. Experimental results show that the pulse charge current has the greatest effect on the charging time and temperature rise, while the pulse discharge current has the least effect on both. The optimal pattern from the Taguchi method is able to charge the cylindrical cell 15.6% faster than the traditional constant current constant voltage (CCCV) charging protocol. An electrochemical and thermal coupled model is developed to reveal the working principle of the CCPC. The modeling results show that the CCPC charging protocol reduces the concentration polarization with more uniform lithium ion distribution than the CCCV, thus accelerating the charging process.

Optimization of Pulse-Step Method for Liquid Steel Alloying in One Strand Slab Tundish

Introduction to the Fe-C-X system: Si, Mn, Al and Nb, Ti, V, B allow the ultimate tensile strength and ductility of steel to be increased at the same time. Therefore, multiphase steels of the TRIP, DP, MART and CP are the steels of the future. The scientific aim of the researches were to obtain new basic information on alloying process of liquid steel in a tundish with the use of the pulse–step method. The facility under investigation was a single outlet tundish being a component of a slab continuous casting machine. Computer simulations of the liquid steel flow and alloy behaviour in turbulent motion conditions were done using the Ansys-Fluent computer program. For generating the computational grids, Gambit program was used. For pulse–step method optimisation two aspects were considered. At first numerical simulations were performed for the selection of the time interval between the pulse feed of the first alloy batch and the continuous feed of subsequent alloy batches in order to maintain the required homogenisation level. Next simulations were done for determination of the mass of the pulse charge that ensures not only the attainment of the 95% homogenisation level, but also the limitation of alloy concentration peaks occurring in the liquid steel and going beyond the 95% homogenisation zone. On the basis of numerical investigations the mixing curves and time mixing for different variants of pulse-step method optimization were obtained.