Sodium/nickel chloride batteries

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. 

The last type of nickel based battery here considered is the so-called sodium-nickel chloride or Zebra battery, firstly developed in 80s in Pretoria, South Africa (Zebra stands for ZEolite Battery Research Africa). The anode is made of liquid sodium, the electrolyte is based on sodium ion conducting -alumina and the cathode is constituted by nickel chloride. This is flooded with liquid NaAlCU which acts as a secondary electrolyte, i.e., its function is to enhance the transport of sodium ions from the solid nickel chloride to and from the alumina electrolyte [19]. They work at high temperature (157°C is the temperature necessary to have sodium in its molten state, but the better performance is obtained in the range 250-350°C) and operate with the following discharge semi- reactions at the anode ... 

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... 

H. Hammerling, Recycling of Sodium/Nickel Chloride Batteries, presented at the DOE Ad Hoc Advanced Battery Readiness Working Group, August 30-31,1994. 

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... 

The prospects of development of sodium ion batteries are very uncertain. The developers of such batteries remember the numerous efforts directed at the commercialization of batteries with a sodium negative electrode and ceramic electrolyte of P-alumina. Intensive development of batteries with the system of sodium-sulfur has been carried out since 1966 (for almost half a century ) and development of batteries with the system of sodium-nickel chloride (ZEBRA batteries) has been performed since 1978. It was assumed that these high-temperature batteries would form a basis for electric transport, but these systems are still referred to in the future tense. 

In Europe, the drive system of the Impact propelled the Opel Impuls2, a conversion vehicle based on the Opel Astra Caravan in 1991. A new, specifically developed AC induction drive unit with IGBT inverter technology was used to build a small fleet of Impuls vehicles see Figure 8.4). The fleet served as an automotive test bed for the integration of various advanced battery systems such as nickel-cadmium, nickel-metal hydride, sodium-nickel chloride, sodium-sulfur, and sealed lead-acid. 

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 ... 

Sudworth JL, Galloway RC (2009) Secondary batteries - high temperature systems - sodium-nickel chloride. In Jiirgen Garche, et al. Encyclopedia of electrochemical power sources. Amsterdam, The Nederland Elsevier BV, p 312... 

Other types of batteries have been introduced to serve specific needs (electric vehicles, electricity storage for grid support, etc.). For this discussion, we have chosen to focus on sodium-sulfur (Na-S) batteries and nickel-chloride-based batteries, which are both so-called high temperature battery systems, and lastly redox flow systems. 

One example is the Mercedes-Benz 5-seater 190 Electro car which develops up to 32 kW (44 hp), has a maximum speed of 115 km/h and an operating range of 150 km. The sodium-nickel chloride batteries were chosen over nickel-cadmium and sodium-sulfur alternatives. The car is shown in Fig. 9.14. 

Fig. 9.14 Mercedes-Benz zero emission class A EV. The car uses a 40 kW (54 hp)—three-phase induction motor developing a rated torque of 155 Nm which can accelerate the ear to 100 km/h in 17 s with a top speed of 120 km/h and a normal usage range of 150 km. Recharging can be made in 6-12 h using normal household sockets. The battery system is sodium/nickel chloride with an energy storage capacity of 100 Wh/kg and a life of over 100,000 km...

Polymer electrolytes can also be regarded as ion-conducting separators. A semipermeable membrane that only allows the permeation of sodium ions (Na ) is the alumina that simultaneously acts as separator and electrolyte in sodium/sulfur or sodium/nickel chloride batteries (Chapter 10). 

To transport people and material growing transportation systems are needed. More and more of the energy for these systems is drawn from secondary batteries. The reason for this trend is economic, but there is also an environmental need for a future chance for electric traction. The actual development of electrochemical storage systems with components like sodium-sulfur, sodium-nickel chloride, nickel-metal hydride, zinc-bromine, zinc-air, and others, mainly intended for electric road vehicles, make the classical lead-acid traction batteries look old-fashioned and outdated. Lead-acid, this more than 150-year-old system, is currently the reliable and economic power source for electric traction. 

Sodium/nickel chloride is a relatively new variation of the sodium/beta technology and was being developed mainly for electric-vehicle applications. There has not been nearly the effort on this chemistry as on the sodium/sulfur battery. 

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. 

TABLE 40.2 Characteristic Comparison between Sodium/Nickel-Chloride tmd Sodium/Sulfur Battery... 

FIGURE 40.5 Schematic diagrams of reference sodium-beta cell and battery configurations (d) monopolar sodium/sulfur cell (SPL XPB cell), and (b) a sodium/nickel-chloride battery Diagram (b) is courtesy of MES-DEA SA). 

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... 

This section on battery-ievel information is organized the same as Sec. 40.3. That is, battery-ievei design considerations specific to the sodium/sulfur technology are presented first. Then, brief descriptions of modern battery configurations and performance for both sodium-beta technologies are provided. For reference, a schematic diagram of an integrated sodium/ nickel-chloride battery system was shown previously in Fig. 40.5b. 

FIGURE 40.17 Electric-vehicle batteries (a) ABB sodium sulfur - B16 (Isft) and B17 (right) and (b) Zebra Z5 sodium/nickel-chloride (Courtesy of Asea Brown Boveri (a) and MES-DEA SA (b)). 

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