The principal chemistries apart from lead/acid and nickel/cadmium offered by Eurobat manufacturers are a variety of silver-based and lithium-based systems for speciality applications. These include silver/zinc primary and secondary batteries and silver chloride/magnesium batteries for military applications and a number of lithium-based primary cells for both military and speciality applications. Lithium/manganese dioxide, lithium/thionyl chloride and lithium/sulphur dioxide batteries are supplied. Secondary lithium cells are also available for telecommunications and other applications.
Possible uses for Lithium batteries
The technical requirements for OEM batteries in Europe cover numerous different applications. These include all construction designs that can be envisaged today as regards energy and performance. Due to this large number of applications, not only do the battery manufacturers have to focus specifically on electrochemical storage possibilities, but they also have to ask for support from technical system analysts and technology planning specialists when leading and accompanying R&D activities, so that the end product is available on time.
Ultracaps
Electrochemical double layer capacitors are new age energy storage devices. They are capable of several hundred thousands of cycles because of their power and energy devices. The electrode material of choice is activated carbon which is infiltrated by an organic electrolyte. UltraCaps are designed to emphasise its dominant characteristics which are high power delivery and long life. Currently 5,10,100,120,1200 and 2700F UltraCaps are available, which can be combined to power modules. Some of today's typical UltraCap applications are power quality/UPS systems as well as industrial and automotive.
Possible areas to introduce new energy storage systems are:
42 V on board systems
Batteries with high power capacities
Start-stop systems, electronic valve regulation, electronic braking systems, electronic power steering
Batteries with high energy capacities
Maintaining comfort features over a limited period with engine off
Preheating of combustion engine components
Electric and hybrid vehicles
Serial/ Parallel/ Both from low emission to zero-emission levels
Fuel cell vehicles
Temporary storage for bridging the ignition process
Batteries are reserved for comfort features. Batteries are used instead for safety critical features such as electronic braking systems
The electrical requirements are concentrated in useful power ranges at low temperatures (-25°C ) with useful energy content. With a 42 V on board system, an expected output is around 5-10 kW. Requested capacities range from 12 Ah to 110 Ah. Far East vehicle manufacturers demonstrate their technical superiority in hybrid vehicle concepts with the use of newer battery technologies such as NiMH or Li-Ion. These technologies are being introduced worldwide for all customers.
In the USA different development targets have been established in both nationally and privately-funded working groups (USABC, PNGV). These groups developed particular measuring methods, which clearly define the technical targets.
Thus, for example the following technical characteristics have been formulated for hybrid vehicle batteries:
x | Slow Response Engine | Minimum Fast response Engine |
Load | 80 kW | 25 kW |
Pulse Performance | 150 kW | 30 kW |
Energy Throughput | 60 MWh | 5 MWh |
Weight | 50 kg | 40 kg |
Volume | 40 l | 32 l |
Table - PNGV targets for "Slow Response Engine" and "Minimum Fast response Engine"
UltraCap Technology
UltraCap technology stresses the advantages of double layer capacitors. Its technological strongholds are high power and long life, i.e. capacitance and - very important for power application - ESR stability.
This is achieved by the use of a carbon cloth, which is infiltrated by a conductive coating that contacts the current collector. On the liquid side a highly conductive organic electrolyte is employed.
UltraCaps utilise a stacking technology of the electrodes. Using this approach it is possible to maximise the power output and keep energy losses low. Stacking leads to a prismatic shape of the cases, which in turn allows a dense packing of UltraCaps in modules.
UltraCap Devices
Power electronic applications require devices, which can deliver some hundreds of Amperes. UltraCaps - manufactured in a range of 4, 8, 100, 120, 1200 and 2700F - were specially designed for these industrial applications. At present the nominal cell voltage is 2.3 V. Higher voltages are obtained by connecting the capacitors in series, which are called power modules.
Properties
Important properties of UltraCap electrochemical double layer capacitors are:
High power density
Low weight
Long life
Several hundred thousand cycles
Maintenance free
Fast charging with high currents
Very high discharge currents
Short circuit prove
Deep discharge prove
Resistant against reverse polarity
Rechargeable with random free currents and charging profiles
Wide temperature range high shock and vibration resistance
NiCd and Pb free