Batteries specific power

The ingredients of a Li-ion battery depend on the desired performance characteristics. For a high-energy application such as a battery for a battery electric vehicle (BEV) without an internal combustion engine, specific energy is the key property to maximize. Alternatively, for a plug-in hybrid electric vehicle (PHEV), the battery specific power is more critical. The battery performance characteristics will determine the amount of active materials and the requisite structural materials that contain them within the battery. We used Argonne National Laboratory s Battery Performance and Cost (BatPaC) model [9,10] to develop a materials inventory for hybrid electric vehicle (HEV), PHEV and BEV batteries. 

Fig. 25. Lithium—sulfur dioxide and lithium —tbionyl chloride high rate batteries profile with (a) power density vs energy density, and (b) specific power vs...

They may be classified by their structure, as coin, cylindrical and pin types. Table 5, 6, 7 respectively show their specifications. Applications of Li -(CF)n batteries as power sources are spreading from professional and business uses, such as in wireless transmitters and integrated circuit (IC) memory preservation, to consumer uses in electronic watches, cameras, calculators, and the like. Pin-type batteries are used for illumination-type fishing floats with a light-emitting diode. Coin-type batteries, which have a stable packing insulation, separator, and electrolyte for high... 

New materials can improve the specific energy of the automobile battery, which is attracting most of the scientific effort. Nevertheless, an increase in specific power can only be obtained by a good understanding of the structural and molecular aspects that affect the electrochemistry of these materials. 

Widely used parameters are the specific energy or power per unit mass (w = W/M, in Wh/kg, orp = P/M, in W/kg). In each battery type the specific energy is a falling function of specific power. Plots of w vs. p (Ragone, 1968) yield a clear illustration of the electrical performance parameters of given types of batteries and are very convenient for their comparison (see Fig. 19.4). 

Fuel cells are also inherently flexible. Like batteries in a flashlight, the cells can be stacked to produce voltage levels that match specific power needs from a few watts for certain appliances to multiple megawatt power stations that can light a community. 

Zn and Cd find application as fuels in primary and secondary electrochemical energy sources. Primary batteries provide power for short periods and can serve as reserve sources of energy. Typical is the Ag oxide—Zn battery which has a specific energy of 350Wh/kg. A special form is the Ag peroxide-Zn system ... 

Technical challenges are twofold to increase the specific power of the battery towards the end of the discharge and to demonstrate in the pilot phase that the processes which have been developed for cell and battery production are capable of meeting the cost targets. 

FIGURE 13 Ragone plot. Acceptable automobile performance requires the specific power and specific energy shown in the upper right corner of the plot. Several secondary battery systems can meet these technical objectives. 

Alternatively, the energy and power are given with respect to the cell or battery mass and are called specific energy and specific power, respectively. 

However, the superiority of batteries over fuel cells in respect to specific power is gradually being ceded to fuel cells. A well-catalyzed proton exchange membrane fuel cell can reach up to 1 kW kg-1. Only batteries involving high temperatures can do as well. 

Fig. 13.37. (A) The idealized Ragone plot. (B) Real Ragone plots for certain batteries. The specific energy declines with the increase of the specific power demanded.

The power delivered by a battery is given by the product of the current flow and the related cell voltage, P = iV[. The maximum power of a battery can be estimated by measuring Tj as a function of current specific power [W kg j and power density [W L j are the parameters used to compare the performance of batteries. 

In a typical electric car a specific power of 400 W kg and a specific energy of 200 Wh kg would mean that it is possible to achieve 0-60 mph (0-96 km h ) acceleration in 9 s with a range of 200 miles (320 km) in standard driving conditions. A lifetime of 10 years at a cost of 100 per kWh would mean that a 4000 battery could be amortized over 10 years. 

Lithium battery systems will be a strong contender as the main system for the future. Their current performance data on specific energy, specific power and cycle life and also current costs should be improved by a factor of more than two. 

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