Sodium nickel chloride cell

Dvorak W, Sodium-nickel-chloride cell. In Wikimedia Commons CC-BY, 2011. Available from http //commons.wikimedia.Org/wiki/File Sodium-nickel-chloride cell.svg. 

ZEBRA battery is actually a Z E B R A (Zeolite Battery Research Africa) battery, that is, sodium-nickel chloride cell. This battery consists of a liquid Na negative electrode and NiCU separated by S-alumina solid electrolyte with Na" conduction. Total cell reaction is as follows ... 

Sodium/sulfur and sodium/metal chloride technologies are similar in that sodium is the negative electrode material and beta-alumina ceramic is the electrolyte. The solid electrolyte serves as the separator and produces 100% coulombic efficiency. Applications are needed in which the battery is operated regularly. Sodium/nickel chloride cells have a higher open-circuit voltage, can operate at lower temperatures, and contain a less corrosive positive electrode than sodium/sulfur cells. Nevertheless, sodium/nickel chloride cells are projected to be more expensive and have lower power density than sodium/sulfur cells. 

FIGURE 40.6 Modem sodium-beta battery cells (a) 3 NGK sodium/sulfur cells (left to right—T4.1, T4.2, T5.1), and (h) an MES-DEA sodium/nickel-chloride cell (ML3). For reference, the dimensions of the largest NGK cell are 91 mm in diameter x 515 mm long while the MES ML3 cell is 36 mm square x 232 mm long. (Photographs courtesy of Tokyo Electric Power Company and NGK Insulators, Ltd. (a) and MES-DEA... 

Finally, some limited attention has been given to appUeations other than electric vehicles. A number of years ago, development of sodium/nickel-chloride cells for aerospace applications was undertaken and, more recently, the use of this technology for powering submarines was evaluated. - The aerospace cells are essentially electric-vehicle cells with an optimized positive electrode and wicks for the sodium, and the secondary electrolyte that ensure operation in micro-g space environments. 

The high ionic conductivity of sodium (3"-alumina suggested that it would form a suitable electrolyte for a battery using sodium as one component. Two such cells have been extensively studied, the sodium-sulfur cell and the sodium-nickel chloride (ZEBRA) cell. The principle of the sodium-sulfur battery is simple (Fig. 6.13a). The (3"-alumina electrolyte, made in the form of a large test tube, separates an anode of molten sodium from a cathode of molten sulfur, which is contained in a porous carbon felt. The operating temperature of the cell is about 300°C. 

Figure 6.13 Batteries using p"-alumina electrolyte, schematic (a) the sodium-sulfur cell and (b) the sodium-nickel chloride (ZEBRA) cell.

Strong contenders for automotive power are the sodium/sulphur and sodium/ nickel chloride batteries, the latter known as the ZEBRA cell. ZEBRA was originally (c. 1979) an acronym devised for commercial security reasons but now it stands for the very apt Zero Emissions Batteries Research Activity . Several European car manufacturers including BMW and Mercedes have incorporated the ZEBRA cell into prototype cars, vans and buses. The performance of the battery far outstrips that of the lead/acid counterpart, as is evident from Fig. 

Safer versions of the lithium battery such as lithium-polymer are also being developed and are already available in small cells. Other battery chemistries (e.g., sodium/nickel chloride (Na/NiCL), nickel/zinc (Ni/Zn)) may be found in small numbers, but will... 

Also in Germany, Mercedes-Benz has been developing electric vehicles for over 30 years. Many of the later vehicles utilized advanced sodium—nickel chloride (ZEBRA) batteries. By 1997, over 1 million km of road testing of these batteries had been accumulated, much of it in the electric version of the Mercedes-Benz A-Class car. In 1994, the company commenced its research on fuel cell vehicles - the New Electric Car (NECAR) programme. Following the evaluation of a series of prototypes, the NECAR 5 was launched in November 2000. This, too, was based on the A-Class car. Power was supplied by a 75 kW fuel-cell system that was fed by an on-board methanol reformer. The car featured a cold-start facility to remove the need for the reformer to... 

FIGURE 40.1 Diagrams showing the basic functionality of the two types of sodium-beta cells (a) sodium/ sulfur, and ib) sodium/nickel-chloride (Diagram (b) is courtesy of MES-DEA SA)... 

SAFT Socidte des Accumulateurs, Fixes et de Trac-lion, 156 Avenue de Metz, 93230 Romainville Secondary batteries, nickel-hydrogen, cuprous chloride, nickel-cadmium, lithium-manganese dioxide thermal cells, nickel-metal hydride secondary, sodium-nickel chloride secondary. See also SAFT (UK) and SAFT (US). (Chloride Alkad is now part of SAFT). 

A battery system closely related to Na—S is the Na—metal chloride cell (70). The cell design is similar to Na—S however, ia additioa to the P-alumiaa electrolyte, the cell also employs a sodium chloroalumiaate [7784-16-9J, NaAlCl, molten salt electrolyte. The positive electrode active material coasists of a transitioa metal chloride such as iroa(Il) chloride [7758-94-3] EeQ.25 or nickel chloride [7791-20-0J, NiQ.25 (71,72) in Heu of molten sulfur. This technology is in a younger state of development than the Na—S. 

The poor efficiencies of coal-fired power plants in 1896 (2.6 percent on average compared with over forty percent one hundred years later) prompted W. W. Jacques to invent the high temperature (500°C to 600°C [900°F to 1100°F]) fuel cell, and then build a lOO-cell battery to produce electricity from coal combustion. The battery operated intermittently for six months, but with diminishing performance, the carbon dioxide generated and present in the air reacted with and consumed its molten potassium hydroxide electrolyte. In 1910, E. Bauer substituted molten salts (e.g., carbonates, silicates, and borates) and used molten silver as the oxygen electrode. Numerous molten salt batteiy systems have since evolved to handle peak loads in electric power plants, and for electric vehicle propulsion. Of particular note is the sodium and nickel chloride couple in a molten chloroalumi-nate salt electrolyte for electric vehicle propulsion. One special feature is the use of a semi-permeable aluminum oxide ceramic separator to prevent lithium ions from diffusing to the sodium electrode, but still allow the opposing flow of sodium ions. 

Nickel chloride is preferred and ZEBRA batteries are based today on nickel chloride and sodium. According to the very simple cell reaction... 

The main cell reaction involves chlorination of high surface area nickel powder with sodium chloride to form the nickel chloride positive electrode and sodium ... 

One innovative aspect of the ZEBRA technology is that the cell is constructed with the reaction products , metallic nickel and sodium chloride in situ that is the cell is in the discharged state, greatly facilitating fabrication. The liquid sodium and nickel chloride are formed by charging the cell. 

As parent metal alters sodium balance and lipid metabolism it induces metallothionein synthesis. Nickel chloride affects the T-cell system and suppresses the activity of natural killer cells. If given orally or by inhalation, nickel chloride has been reported to decrease iodine uptake by the thyroid gland. 

---