Nickel/cadmium batteries are also used for standby as well as other applications. They are available with pocket-plate or sintered electrodes in steel or plastic containers. A full range of applications is served and nickel/cadmium is especially suited to electrically or mechanically arduous applications.

Nickel/cadmium batteries have a positive electrode of nickel hydroxide and a negative electrode of cadmium.

On discharge the nickel hydroxide is reduced to a different form of nickel hydroxide with a lower oxidation state and the cadmium is oxidised to cadmium hydroxide. The reverse reactions take place on recharge. The electrolyte is a potassium hydroxide solution. The construction of the battery differs for particular applications but there are two basic types; either a pocket-plate type or types using a sintered or bonded electrode structure. For pocket-plate types, a perforated nickel-plated steel pocket is used to contain the active material. For sintered or bonded types, a porous partially sintered nickel substrate may be used but various plastic bonded structures and fibrous constructions are also offered. The pocket-plate construction is highly reliable and offers moderate performance but the other types offer higher levels of electrical performance. Nickel/cadmium batteries may also be constructed in a fully sealed form similar to VRLA batteries.

Nickel/cadmium batteries offer good resistance to electrical use as they can be left in a discharged condition for long periods without permanent damage and also offer good performance in higher ambient temperatures.

bron: www.eurobat.org

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:

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