ZEBRA Batteries Research Articles

The ZEBRA electric vehicle battery: power and energy improvements

Vehicle trials with the first sodium/nickel chloride ZEBRA batteries indicated that the pulse power capability of the battery needed to be improved towards the end of the discharge. A research programme led to several design changes to improve the cell which, in combination, have improved the power of the battery to greater than 150 W kg−1 at 80% depth of discharge. Bench and vehicle tests have established the stability of the high power battery over several years of cycling. The gravimetric energy density of the first generation of cells was less than 100 Wh kg−1. Optimisation of the design has led to a cell with a specific energy of 120 Wh kg−1 or 86 Wh kg−1 for a 30 kWh battery. Recently, the cell chemistry has been altered to improve the useful capacity. The cell is assembled in the over-discharged state and during the first charge the following reactions occur: at 1.6 V: Al+4NaCl=NaAlCl4+3Na; at 2.35 V: Fe+2NaCl=FeCl2+2Na; at 2.58 V: Ni+2NaCl=NiCl2+2 Na. The first reaction serves to prime the negative sodium electrode but occurs at too low a voltage to be of use in providing useful capacity. By minimising the aluminium content more NaCl is released for the main reactions to improve the capacity of the cell. This, and further composition optimisation, have resulted in cells with specific energies in excess of 140 Wh kg−1, which equates to battery energies>100 Wh kg−1. The present production battery, as installed in a Mercedes Benz A class electric vehicle, gives a driving range of 205 km (128 miles) in city and hill climbing. The cells with improved capacity will extend the practical driving range to beyond 240 km (150 miles).

Development of a High Performance Zebra Battery for Electric Vehicle Applications

Development of a High Performance Zebra Battery for Electric Vehicle Applications

ZEBRA battery meets USABC goals

Abstract In 1990, the California Air Resources Board has established a mandate to introduce electric vehicles in order to improve air quality in Los Angeles and other capitals. The United States Advanced Battery Consortium has been formed by the big car companies, Electric Power Research Institute (EPRI) and the Department of Energy in order to establish the requirements on EV-batteries and to support battery development. The ZEBRA battery system is a candidate to power future electric vehicles. Not only because its energy density is three-fold that of lead acid batteries (50% more than NiMH) but also because of all the other EV requirements such as power density, no maintenance, summer and winter operation, safety, failure tolerance and low cost potential are fulfilled. The electrode material is plain salt and nickel in combination with a ceramic electrolyte. The cell voltage is 2.58 V and the capacity of a standard cell is 32 Ah. Some hundred cells are connected in series and parallel to form a battery with about 300 V OCV. The battery system including battery controller, main circuit-breaker and cooling system is engineered for vehicle integration and ready to be mounted in a vehicle [J. Gaub, A. van Zyl, Mercedes-Benz Electric Vehicles with ZEBRA Batteries, EVS-14, Orlando, FL, Dec. 1997]. The background of these features are described.

Die Zebra-battery - ’n Suid-Afrikaanse aanspraakmaker in die elektriesevoertuigbedryf

The Zebra battery is one of the most promising power sources for electric vehicles which might be on sale before the year 2000. It is a South African development which started at the CSIR and is at present jointly managed by the Anglo American Corpora­tion of S.A. and the German company A.E.G. The chemical reaction converts common salt and nickel to nickel chloride and sodium during the charging phase.

Review of the zebra battery system development

The Zebra battery system for electric vehicle applications has been under development for more than ten years. This paper will review the status of the system development and will focus on the following aspects: A review of the basic electrochemistry of the sodium-nickel chloride electrochemical cell will be presented. In particular, the research and development work on the synthesis and manufacture of pure phase β″-alumina materials will be discussed. In conclusion, the integration of the electrochemical cells into a traction battery for electric vehicle applications will be described.

Zebra batteries

By using molten sodium chloroaluminate as secondary electrolyte, a series of solid transition metal chlorides can be used as positive electrodes in cells with sodium as the negative and beta-alumina as the solid electrlyte. Nickel chloride is preferred and Zebra batteries based on this cell reaction have been developed to the pilot-line production stage. The batteries have a number of features which make them attractive for electric-vehicle applications. Thus, the cells can be assebled in the discharged state eliminating the need to handle liquid sodium. By locating the positive electrode inside the beta-alumina tube, square cell cases can be used giving maximum packing efficiency in batteries. The absence of corrosion in the cell leads to a long life and high reliability. For electric-vehicle applications safety is very imporant, and crash testing has shown that even serious damage to the battery in a crash situation would not present a significant additional hazard to the driver or passengers. The remaining technical challenges are to increase the specific power of the battery towards the end of discharge and to demonstrate that the processes, which have been developed for cell and battery production, are capable of meeting the cost targets.

An Electrochemical and Spectroelectrochemical Study of the Behavior of Cobalt Electrodes in Molten Aluminum Chloride: Sodium Chloride Mixtures

The electrochemical behavior of cobalt electrodes has been studied in melts at temperatures in the range 175°–215°C. Anodic oxidation commences at potentials positive of 0.9V vs. an aluminum reference electrode in the same melt, producing solid and a small amount of cobalt in solution. Spectroelectrochemical measurements revealed that the dissolved cobalt was present as . As the oxidation proceeds and Cl− is consumed, the melt in the vicinity of the electrode becomes acidic; oxidation can then continue at a higher potential of about 1.3 V vs. the aluminum reference. Rapid anodic/cathodic cycling leads to increasing currents at the electrode. This and other observations are most easily explained by postulating that solid is precipitated on the electrode surface during the cathodic part of such cycles. Implications for the Zebra battery system are discussed.