Automotive Li-Ion Batteries: Current Status and Future Perspectives

Nickel–Cadmium Cells Cell Fabrication Methods Silver–Zinc Cells Performance Other Silver Positive Electrode Systems Nickel–Zinc Cells Nickel–Hydrogen Cells Other Cell Systems Electrolyte Safety and Disposal Keywords: sealed cells; secondary cells

This paper compares AA size nickel metal hydride (Ni-MH) cells with comparable AA nickel cadmium (Ni-Cd) cells both of which were obtained in 1993. The Ni-MH cells were found to be a suitable substitute for conventional Ni-Cd cells. Both these cell types have similar voltages and discharge characteristics. The Ni-MH cells, though, had nearly twice the capacity as comparable Ni-Cd cells. There was no significant difference in self discharge between the two types of cells. The Ni-MH cells also performed as well as Ni-Cd cells at rates lower than 5 amperes and at temperatures higher than 0/spl deg/C (32/spl deg/F). The most interesting finding is that the Ni-MH cells showed an irreversible decay of the discharge voltage with each cycle which was more noticeable during pulses. Eventually the Ni-MH packs fail, not because of loss of capacity, but because of low voltage during the pulse.

A spreadsheet model for the analysis of batteries of various types has been developed that permits the calculation of the size and performance characteristics of the battery based on its internal geometry and electrode/electrolyte material properties. The method accounts for most of the electrochemical mechanisms in both the anode and cathode without solving the governing partial differential equations. The spreadsheet calculations for a particular battery design are performed much like a battery test in that the C/3 capacity of the battery to a specified cut-off voltage is determined and then the pulse power capability at a given state-of-charge is determined by finding the maximum current density (A/cm/sup 2/) for which the cell voltage equals a specified minimum value. For a multi-cell module, the module characteristics are calculated using the cell results and packaging input information. The spreadsheet model has been validated for existing lead-acid (Sonnenschein), nickel cadmium (Saft), and nickel metal hydride (Ovonic) batteries for which test data and internal geometry information are available. Various battery designs were then evaluated using the method to show how batteries having high power densities (greater than 500 W/kg) could be designed. The spreadsheet model permitted the determination of the critical design parameters for high power lead-acid, nickel cadmium, and nickel metal hydride batteries.

Battery selection remains an up-to-date engineering problem for hybrid and electric vehicle manufacturers. Type of battery and its capacity will depend on the trip and vehicle parameters. An electric vehicle produced with the ideal bat-tery type will undoubtedly be preferred by customers. Data collected from black boxes of trolleybuses operated by Malatya Metropolitan Municipality were used in this study. The real road and driver characteristics were included in the study with the experimentally obtained data. These data are the accelerator pedal data obtained from vehicles driven by different drivers in regular and congested traf-fic hours. In this study, four different battery chemistries were run separately on a hybrid vehicle model and analyzed. Chosen battery chemistries are the most commonly used by manufacturers. These are Lead Acid, Nickel Cadmium, Nickel Metal Hydride and Lithium Iron Phosphate batteries. The results of the study are presented in detail comparatively. Among the battery chemistries, Lithium iron phosphate is observed to be the most ideal battery type for hybrid electric vehi-cles.

The polarization characteristics of potential electrochemical components of an unregulated battery hybrid system were studied. The components under study included two lead-acid cells (2 Ah prismatic cell and a 1 Ah cylindrical cell), and a 1.7 Ah cylindrical nickel metal hydride cell as the high power density but low energy density component, and a 30 Ah zinc-air cell as the high energy density but moderate power density component. The prismatic lead-acid cell was found to have more favorable characteristics than the cylindrical design for an electrochemical battery hybrid system. In comparison to the lead-acid system, the nickel-metal hydride cell, because of its greater charge potential and current required, is not a good candidate for an unregulated hybrid system. The zinc-air system has desirable polarization characteristics for the high-energy hybrid component. Overall, under identical load and cut-off voltage, a hybrid system utilizing the zinc-air and lead-acid batteries provided 40% greater energy than a zinc-air/nickel-metal hybrid system, translating to longer operational time.

The ultra-fast charging capability, distinct properties, fine performance and high capacity of nickel cadmium (Ni-Cd) and nickel metal hydride (Ni-MH) batteries along with their limited weight and size are very attractive for use in many applications including cordless and portable devices, emergency and standby power, telecommunication equipments, photovoltaic systems, electric vehicle, satellite and space craft and power plant supporting equipments. However, the limitation on their temperature requires a detail thermal analysis of these batteries. Thermal behavior of batteries are effected by their boundary conditions, type and construction, and more importantly by their chemical reaction. The purpose of this study is to investigate the effect of temperature on thermal behavior of the Ni-Cd and Ni-MH batteries. The governing equation is the transient and non-linear differential energy equation subjected to non linear radiation boundary conditions and source term. To solve the transient and non-linear governing differential energy equation a control volume based finite difference code is utilized. In formulation of the governing differential energy equation, the Ni-Cd and Ni-MH properties (K, C, ρ) are not constant and the chemical characteristic of the Ni-Cd and Ni-MH batteries, source term, vary with location and time. Calculated thermal characteristic of each battery is then compared to experimental results. The result shows that Ni-MH battery is thermally more suitable for space application and satellite.

In last years, NiCd and NiMH technologies have settled in the market of medium/high capacity batteries. Fast-charge is very interesting in different applications (communications systems, electric vehicles, low-earth-orbit spacecrafts) in order to minimizing charge time. The problem is that high currents involved in fast-charge process affect battery behavior modifying parameters as battery charge acceptance. Moreover, battery temperature increase and gasses production related to overcharging make necessary to detect accurately the end of fast-charge to avoid battery damage. Limited information about results of charging process at different charging rates (i.e. time reduction versus charge efficiency) makes difficult to select the optimum rate in each specific application. The lack of information is more problematic in NiMH batteries due to they can not support as well as NiCd batteries extreme working conditions. For these reasons, an intensive study about NiCd and NiMH battery behavior under different charging rates was developed. In this paper, the effects of fast-charging on medium/high capacity NiCd and NiMH batteries are shown. In this way, conclusions about the application range of fast-charging in both technologies are drawn

Transition to electric vehicles is becoming increasingly significant due to climate change crisis, but it may follow different paths for developing countries as motorization rates have not reached saturation. This study introduces a novel approach for forecasting electric vehicle market penetration under increasing motorization rates. Motorization rate growth and electric vehicle market penetration are concurrently forecasted using a three-step process including estimation of (i) motorization rate based on gross domestic product forecasts by Gompertz model, (ii) number of passenger cars using population projections, and (iii) electric vehicle market penetration rate using a logistic growth model. The numerical analysis used gross domestic product estimates, population projections, and passenger car data for Turkey; the results reveals exponential growth in electric vehicle numbers until 2040, followed by a slower increase until 2060. Under different economic growth scenarios, the estimated number of electric passenger cars ranges from 19.2 to 51 million by 2060, showing a great difference due to variations in expected motorization rates. Sensitivity analyses highlight that gross domestic product per capita significantly influences electric vehicle penetration more than motorization rate saturation rates. These findings show that targeted strategies for supporting electric vehicle adoption in countries with unsaturated vehicle fleets can help policymakers shape incentives and policies. This study has a unique contribution by the methodology filling a critical modeling gap in electric vehicle penetration studies for markets with rising motorization rates. Thus, an accurate and consistent framework for predicting and planning electric vehicle adoption in different economic contexts is presented.

Electric Vehicles (EVs) can contribute significantly to reducing greenhouse gas emissions and addressing climate change problems. Modern EVs are primarily powered by electrochemical batteries such as lead-acid (Pb-acid), nickel-metal hydride (NiMH), sodium-ion (Na-ion), solid-state and lithium-ion (Li-ion) batteries. When compared to other battery types, Li-ion batteries are the most suitable for EV applications due to their practical features such as their high energy density, high charging and discharging efficiency and extended lifetime. However, the main risk of Li-ion batteries is that they are exposed to thermal runaway phenomena, which raises severe concerns about the safety of EV propulsion systems. Thermal runaways should be considered carefully as they cannot be stopped once they start and can lead to battery explosion. One of the main reasons leading to this phenomenon is abusing the state of charge (SoC) of the battery. Therefore, the battery management system (BMS) plays a crucial role in mitigating the stimulation of the thermal runaway process by accurately estimating and properly managing the battery cells. To help researchers and designers with understanding this matter, this paper proposes a review of the most effective SoC estimation methods for EV Li-ion batteries and links these methods with practical energy management systems in the EV market.

Summary form only given. The nickel metal hydride (Ni-MH) battery provides a near-term answer to the demand for portable, rechargeable power sources which are lighter and smaller than nickel cadmium batteries. Commercially available Ni-MH batteries can substitute for nickel cadmium (Ni-Cd) batteries cell for cell, with almost indistinguishable voltage characteristics, but provide 2540 percent more energy and are free of environmentally undesirable cadmium. Ni-MH battery packs are finding immediate use in portable electronic applications such as laptop, notebook, and sub-notebook computers, cellular communication devices, and consumer electronic devices such as camcorders. Ni-MH battery packs which have been carefully designed to retrofit existing Ni-Cd packs can be charged safely, and in nearly all cases effectively, by the existing installed base of Ni-Cd battery chargers. Ni-MH battery technology is well positioned to power the next generation of electronic devices which will combine computers and digital electronic communications technology. >

Nickel metal hydride batteries bring some unique values to stationary applications - high energy and power densities, cycle life, quick charge capability and safety, to name a few. Since the late 80's, small cylindrical nickel metal hydride batteries have been widely used in portable applications requiring high rate discharge and rapid recharge, for example, camera flash and power tools. Recently, large prismatic nickel metal hydride batteries have become the technology of choice in hybrid electric vehicles due to their good cycle life, wide temperature range of operation and high rate capability. Additionally, these batteries have been tested and installed in large stationary applications due to their unique values. In one of those applications, a flooded lead acid battery system, used to back up 560 kW, was replaced with nickel metal hydride battery system to provide the same 15 minutes of back up time. A case study with this large nickel metal hydride battery installation will be presented in this paper

Chapter 5 - Rechargeable Batteries and Their Management

Chapter 9 - Rechargeable Batteries and Their Management

Diesel or gasoline engine cold cranking is a serious problem for different vehicle operation in northern countries. The engine starting torque is usually provided by an on-board electrochemical battery represented by a lead-acid unit. Modern energy storage devices, such as supercapacitors (SCs), lithium-ion, nickel-cadmium (NiCd) and nickel-metal hydride (NiMH) batteries react differently on low temperatures. Moreover, capacity losses also occur. Considering wide applications of such storage devices in electrical vehicles, their behaviour at low temperatures is of interest. Physical simulation of storage battery cold cranking was carried out using a climate chamber. Lithium-ion, NiCd, NiMH and lead-acid batteries were tested individually and paired with a SC unit to generate a power impulse for engine cranking. A number of experiments (up to five) for each type of storage devices were taken. The best performance results both for direct and hybrid cranking simulation were showed by LiFePO4-based and Ni-Cd batteries. The SC module itself showed the best performance, but its specific energy capacity cost is too high to have a large battery system based on SCs only. In this case a combined storage could give enough power to fulfill cranking demands.

Cell components – Separator | Current collectors for secondary batteries