• Daowd, Mohamed Ali Abdelfattah Hamoda
• Pauwels, S.
• Omar, Noshin
• Van Den Bossche, Peter
• Van Mierlo, Joeri
• Mulder, Grietus
• Verbrugge, Bavo

Abstract

This paper presents the performance characteristics of ten commercial lithium-ion brands of various chemistries for use in Plug-in Hybrid Electric Vehicle applications. The cells chemistries are based on iron phosphate, nickel manganese cobalt oxide and nickel cobalt aluminum in the positive electrode. The experimental results indicate that nickel manganese cobalt oxide based cells show the best energy density in the range of 126 - 149Wh/kg compared to 75 - 118Wh/kg for cells using iron phosphate in the positive electrode. The results illustrate that the power densities of the most iron phosphate cells varies between 320 and 1650 W/kg. The variation in W/kg can be explained that some of the tested cells (higher than 20Ah) are primarily suitable for Battery Electric Vehicle applications rather than PHEVs. While the energy and power capabilities of nickel cobalt aluminum based cells seem to have less favorable performances: 90Wh/kg and 290W/kg. From the point-of-view of energy efficiency LiNiCoMnO2 technology show favorable performances around the 95% compared to 88 - 90% for the other battery chemistries. The good performances of LiNiCoMnO2 cells are mainly due to the higher nominal voltage, good electrode specific capacities and a good specific impedance. <br/>In the framework of this research, a new modified equation has been proposed in order to calculate the state of charge of lithium-ion batteries. However, the equation can be also useful for other battery technologies as lead-acid and nickel metal hydride. This equation contains important aspects which are related to a battery behavior such as energy efficiency in function of state of charge, current, temperature and cycle life. Furthermore, the influence of the Peukert constant in function of temperature and cycle life has been integrated. <br/>In this report, the thermal behavior of several batteries design concepts under discharge conditions has been investigated. The analysis showed that the heat development in prismatic cells is mostly located at the terminals. While, the heat production in cylindrical cells is more homogeneous. Due to the relative available little surface area in cylindrical cells, the external and internal temperature gradient becomes greater. Therefore, the heat distribution for both battery design concepts is not optimal which results primarily in less capacity that the battery can deliver. In the case of pouch cells, the heat development is less dramatic due to the larger external surface and lower temperature gradient. <br/>Then, the cost and cycle life considerations for the proposed batteries have been analyzed. According to the USABC requirements, only iron phosphate based batteries can reach the goal of 200 - 300$/kWh. From the standpoint of the cycle life, there is no battery technology on the market which can meet the objectives of 5000 cycles. The average cycle life of most commercial lithium-ion batteries is in the range of 1000 - 1200 cycles according to data sheets (100% DoD). <br/>In this research a new test methodology has been developed at the Vrije Universiteit Brussel and VITO research institute which is able to investigate all the evaluation criteria as discussed above. <br/>In addition, the proposed methodology can provide all necessary parameters for several battery models as FreedomCar, second order FreemdomCar, Thevenin and Shepered.

Topics

• density
• impedance spectroscopy
• surface
• energy density
• nickel
• aluminium
• laser emission spectroscopy
• cobalt
• Lithium
• iron
• Manganese