Zebra battery
The abbreviation stands for English ZEBRA Zero Emission Battery Research Activities.
A sodium - nickel-chloride cell, also referred to as Zebra battery is a rechargeable battery, a so-called secondary cells. It is one of the thermal batteries. Instead of a liquid electrolyte, a solid electrolyte and a combination of liquid and solid electrode can be used. Is used the battery in electric cars and in the defense industry.
History and manufacturers
The cell was developed in the late 1970s of the South African company Zebra Power Systems and Beta R & D Ltd., which for a first patent was awarded in 1978. The company Beta Research and Development further developed the technology before it was taken over in 1988 by the later AEG Anglo Batteries GmbH with the participation of Daimler AG. From the AEG Anglo Batteries GmbH production were developed and built operational traction batteries for electric cars since 1994, so for the Mercedes -Benz A study as well as for the later series production also developed as an electric car A-Class
After setting of this project and the merger of Daimler and Chrysler AG technology and patents to MES -DEA were sold in Switzerland. MES -DEA has then produced until 2009 Zebra batteries and also equipped motor vehicles with electric motors and Zebra batteries, including Twingo, Smart and Panda. At the site Stabio in Switzerland, the batteries have been produced since about 1998. From MES -DEA and the Italian FIAMM battery manufacturer FZ SONICK was first established in 2010 and renamed after the acquisition of 100 percent of the shares by FIAMM on 1 July 2010 in FIAMM SoNick SA. With the founding of FC SONICK MES -DEA has given up this field of business and hand over the vehicle conversion company Kamoo AG. In 2010, the company FIAMM SoNick SA in Stabio ( Switzerland ) is next to Rolls Royce in the UK major manufacturer of Zebra batteries.
Structure and properties
The reactants are sodium chloride (salt ), with a liquid salt solution of nickel chloride and sodium chloride soaked sintered nickel as a positive electrode, and separated by a separator outside liquid sodium as the negative electrode. Separating in the separator is maintained by a permeable to sodium ions only semi-permeable ceramic wall / separates the electrode from the sodium chloride, sodium / nickel chloride nickel electrode and also serves as a solid electrolyte. An essential component of the ceramic is sodium - β - aluminate ( NaAl11O17 ) in which starting from a temperature of 270 ° C, the sodium ions are movable so that a sufficient conductivity. It is advantageous that the pure sodium metal in liquid form at the negative electrode, which prevents the buildup of inactive and destructive connections ( dendrites ).
The operating temperature of the thermally insulated by vacuum insulation battery is typically 300 ° C (270 to 350 ° C). The battery has no electrochemical self-discharge, the efficiency is around 80%. However, the cell to maintain the function at a high operating temperature must be maintained, thereby heating is necessary despite thermal insulation. While at a sufficiently high energy removal, the thermal losses in the internal resistance of the cell is sufficient for keeping the temperature at not use an additional heater is required, which, when it concerns their power from the cell, resulting in a constant discharge.
In terms of lifetime reports a test battery that has been used for eleven years in the test and about 3000 cycles ( which is about one cycle per day). There were presented two types: both, each with 17.8 kWh capacity, even at 278 V with 64 Ah and once at 557 V and 32 Ah. The blocks each weighing 195 kg with case and battery management, the specific energy of 94 Wh / kg. The maximum power is approximately 32 kW according to the manufacturer. Batteries, which were cooled below the melting point of the salts can be reactivated by heating. When cooled it can be considered to have an indefinite shelf life, since the chemical substances are inactive. For the number of Abkühl-/Aufheizzyklen the manufacturer makes no official statement. It can be assumed that frequent heating and cooling, resulting in mechanical stress of the ceramic membrane. However, the occasional cooling of the battery in practical use is unproblematic.
The energy content of about 100-120 Wh / kg. In contrast, a lead-acid battery has an energy content of about 30 Wh / kg. Per kWh of storage a Zebra battery requires 1.53 kg of nickel, iron 1.43 kg, 0.31 kg of copper, 2.24 kg of NaCl, and 1.43 kg of aluminum hydroxide ( boehmite).
The starting materials are inexpensive yet compared to other battery technologies in sufficient quantities. The preparation is relatively easy. The current high cost / kWh explained mainly from the small quantities produced and could be significantly reduced with automated mass production. In Switzerland, a study of the entire life cycle assessment using the example of a Twingo was performed with Zebra battery. The results confirmed that only when operating with pure coal power or very unfavorable usage profile of the Zebra battery ( long life ) the environmental performance of electric cars worse than the can fall out of vehicles with internal combustion engines.
Electrochemistry
The overall reaction during discharge is:
During charging, the operation in the reverse direction runs. The cell voltage at no load, the charged cell is typically 2.58 V. This voltage depends not only on the structure of the cell and of the load speed. In addition there are further variants, for example, with electrodes made of sintered iron instead of nickel. These cells have an open circuit voltage of 2.35 volts.
Applications
Electromobility
Even the development of the Zebra battery was closely associated with electric mobility, triggered by the CARB legislation in California, linked. MES -DEA has then produced until 2009 Zebra batteries and also equipped motor vehicles with electric motors and Zebra batteries, including Renault Twingo, Smart and Panda. These were distributed in Switzerland and Italy. In the hybrid rural- O 405 NÜH, a duo - bus, 1996, a 800 kg traction battery was installed on the vehicle roof.
The currently best known car with Zebra battery is the Think City and the Smart EV in a limited edition for London, UK. Even the world's largest manufacturer of Elektrovans and electric trucks Smith Electric Vehicles uses Zebra battery packs, such as the Smith Newton range, a 7.5 -ton truck with a 120 -kilowatt electric motor. Also in hybrid buses in Italy and all-electric buses in California ZEBRA batteries have been fitted. Zebra batteries are available in various electric vehicles also in use in Germany, including in a Daimler bus MB410E of BIMAQ, Bremen and in a converted by the company cancer and Aulich to electric drive Audi A2. In France, the post was 2011/2012 equipped with electric vehicles of the type Peugeot Partner and Citroen Berlingo, which are equipped with Zebra batteries. The equipment was carried out at the venturi. Also the van Iveco Daily Electric is equipped with a ZEBRA battery, this is for example test employed by Deutsche Post DHL since 2011 in small numbers.
Mobile phone base stations
Because of the long life and problem-free heating as stationary battery -powered to a place they are increasingly installed in mobile phone base stations as a buffer battery. Manufacturers, for example, General Electric.
Weapons systems
Because of their high energy density and reliability ZEBRA batteries are also used in weapons systems such as submarines and missiles. European manufacturers such as Rolls- Royce. Rolls- Royce offers ZEBRA batteries from 24 V to 1000 V and with a capacity of 2 kWh to 50 kWh.