Power Density Of Batteries Research Articles

Schweizerisches Energieforschungsprogramm Elektrochemie

The need of advanced power sources especially for electric vehicle and load leveling applications motivated the Swiss government to promote a research program in electrochemistry. This program concentrates on research of electrode and electrolyte materials which are of interest for the development of new energy-storage and conversion devices such as advanced batteries, fuel cells, and electrolysers. The program involves researchers from different disciplines and institutes. Material research, electrochemical engineering, and system modeling are the main topics of the program. The material research is concentrating on electrode materials with high energy content like Li, Al, Mg, Ca, and insertion electrodes. Important research topics are also conducting polymers, redox polymers, and polyelectrolytes or solid electrolytes. In a later stage, the research achievements should be used to develop high power density batteries and fuel cells.

1974 Energy Requirements for Electric Cars and Their Impact on Electric Power Generation and Distribution Systems

Assuming the availability of a high energy and power density battery of 100 Wh/lb and 100 W/lb by the 1980's, the energy consumption and efficiency of electric and heat engine cars are compared on an equal basis. This is achieved by considering a reference electric car of 3150-lb weight similar in body construction, aerodynamics, and rolling resistance to a conventional heat engine car of equal weight, and comparing the performance of the two cars over the same driving modes. The reference electric car is then used as a baseline to evaluate the possible improvements in future electric cars. The energy consumption for an optimized 2000-lb electric car of driving range, comfort, and performance comparable to a conventional car is estimated. Assuming a gradual growth in electric car population leading to their widespread use by the 1990's, the impact on electric power generation and distribution systems is estimated. Though the analysis is based on a high energy and power density battery the results may be extrapolated to electric cars using lower performance batteries. It is noted that batteries with lower energy density can provide sufficient driving range to fulfill a significant portion of our transportation needs and their continued development and improvement will accelerate the achievement of the high energy- density goal [1].

State of development and prospects of sodium/sulfur batteries

The status of development of sodium/sulfur batteries is reviewed and properties to be achieved within the next years are forecasted. Cells with an energy density ≈5 times higher and a maximum power density 2 times higher than the corresponding quantities of lead acid cells are attained. Average cycle life amounts to 500 cycles, several cells surpassed 1000 cycles. The performance did not appreciably decrease during this period of time. Batteries containing ≈100 cells have been operated. The electrical behaviour corresponded to that of single cells. Conventional heat insulations were used to keep the batteries on operation temperature. Non-conventional insulations the weight and volume of which will be considerably decreased compared to present insulations are in development. It is expected that reliability and lifetime statistics of cells as well as energy and power density of batteries can be further increased so that final battery performance will be much better than that of conventional batteries. The range of Na/S-battery propelled vehicles will be higher than those of today's electric vehicles. Utilisation of batteries for the propulsion of electric vehicles and for load leveling will contribute to substitution of crude oil by other primary energy resources.

Energy Requirements for Electric Cars and Their Impact on Electric Power Generation and Distribution Systems

Assuming the availability of a high energy and power density battery of 100 Wh/lb and 100 W/lb by the 1980' s, the energy consumption and efficiency of electric and heat engine cars are compared on an equal basis. This is achieved by considering a reference electric car of 3150-lb weight similar in body construction, aerodynamics, and rolling resistance to a conventional heat engine car of equal weight, and comparing the performance of the two cars over the same driving modes. The reference electric car is then used as a baseline to evaluate the possible improvements in future electric cars. The energy consumption for an optimized 2000-lb electric car of driving range, comfort, and performance comparable to a conventional car is estimated. Assuming a gradual growth in electric car population leading to their widespread use by the 1990's, the impact on electric power generation and distribution systems is estimated. Though the analysis is based on a high energy and power density battery the results may be extrapolated to electric cars using lower performance batteries. It is noted that batteries with lower energy density can provide sufficient driving range to fulfill a significant portion of our transportation needs and their continued development and improvement will accelerate the achievement of the high energy-density goal [1].

Testing Batteries for Vehicular Applications: III . Selection and Characterization of a Power Battery

The problem was to find an acceptable “power” battery (i.e., a high power density battery to deliver short time acceleration pulses) for an electric commuter vehicle concept powered by a dual battery system. A number of batteries were tested, both Pb‐acid and Ni‐Cd. The best battery was a Ni‐Cd aircraft starting battery. It could deliver 14 consecutive 1900W, 10 sec acceleration power pulses. It was calculated that about 180 lb of battery would be required for the particular power plant design envisioned. The high cost and scarcity of Cd militated against the use of a Ni‐Cd battery. The next best candidate was a Pb‐acid aircraft starting battery designed for high current drains for short time periods. It, too, delivered 14 consecutive 1900W, 10 sec pulses. In addition, it had sufficient energy capacity to provide some low speed range in the event of failure of the “base‐load” energy battery. It had a power density of 70 W/lb at an energy density of 2 Whr/lb. About 270 lb of this battery would be required for the “power” battery pack. A Delco‐Remy 2HN‐11A military battery was tested to yield design data for the power plant. From these data, a battery was designed which would fit into an available lightweight container. Prior to this, a 2HN‐11A modified battery was tested to confirm the design. Test results confirmed the designed capacities.Several of the design batteries were built. Each consisted of seven cells containing 11 plates per cell. One of the batteries was tested. It delivered 15 consecutive 2500W acceleration power pulses to 10.5V. It weighed 32 lb; hence, the entire power pack would weigh 256 lb. Since the 11‐plate cell performed so well, it was hoped that a 9‐plate cell might just deliver adequate power. A 27 lb weight reduction would be realized. However, it could not deliver adequate power when tested. Nothing could be obtained at 2500W. The voltage fell immediately below 10.5. In fact, only 1.8 min were obtained at 1900W.