Sodium/sulfur batteries development

Harlow, R. A., McClanahan, M. L. and Minck, R. W (1984) Sodium-sulfur battery development. ExtendedAbstracIs Sixth DOE Electrochemical Contractors Review. Vl shington, DC, USA 25-28 June 1984... 

Sodium-Sulfur Battery Development (19821 Interim Reoort, 1 March 1980 to 30 September 1981, DOE Contract No. DE-AM02-79Ch10012... 

Sodium, generally about 99.9% Na assay, is available in two grades regular, which contains 0.040 wt % Ca, and nuclear (low Ca), which has 0.001 wt % Ca. Both have 0.005 wt % Cl . The nuclear grade is packed in specially cleaned containers, and in some cases under special cover atmospheres. A special grade of sodium low in potassium and calcium (<10 ppm) is achievable to meet requirements for use in manufacture of the more newly developed sodium—sulfur batteries. 

Though sodium-sulfur batteries have been under development for many years, major problems still exists with material stability. It is likely that the first commercial uses of this batteiy will not be for electric vehicles. Sodium-sulfur storage batteries may be more well-suited for hybrid electric vehicles or as part of a distributed energy resources system to provide power ill remote areas or to help meet municipal peak power requirements. 

Another direction of battery development involves high temperature and larger units. NGK Insulators, Ltd., in Japan uses sodium-sulfur batteries operating at 427°C (800°F) that are able to deliver 1 mW for 7 hours from a battery unit. The size of these units is about the size of a bus. Such units could be used at electric filling stations that are not connected to the grid. 

Among the various electrolytes, yttrium stabilized zirconia (YSZ) has been developed, for use in high-temperature fuel cells and oxygen sensors similarly, various S( S")-alumina materials are in development for sodium sulfur batteries. 

Since the principle of the sodium sulfur battery was established in 1967, it has been under development throughout the world. The schematic set-up of a sodium sulfur battery, operated at 300 350 °C, is shown in Figure 22. Molten sodium, the anode active material, is placed in a sintered S-alumina solid electrolyte tube, and molten sulfur impregnated in the porous graphite cathode, outside. The... 

Current developments in battery technology, electrochromic devices (see Box 22.4) and research into electrically powered vehicles make use of solid electrolytes (see Box 10.3). The sodium/sulfur battery contains a solid 3-alumina electrolyte. The name (3-alumina is misleading since it is prepared by the reaction of Na2C03, NaN03, NaOH and AI2O3 at 1770K and is a non-stoichiometric compound of approximate... 

Much of the effort to develop the Na/S battery was aimed at its use in electric vehicles. Current applications of this advanced battery system are now mainly in the stationary battery area, but feasibility studies were done on the recycling of this system before the EV development efforts were suspended. Sodium/sulfur batteries contain reactive and corrosive materials, but not toxic ones. By treatment of the battery waste, the reactivity problems can be removed. 

Another example is P-alumina, Na20 AI2O3, and derivatives. It consists of aluminum oxide layers separated by intermediate layers of sodium and oxygen ions. The sodium ions are partially located on interstitials in channels with high mobility at ambient temperatures. The conductivity of sodium ions is of the order of 0.2 S cm at 3(X) °C. The conductivity in some derivatives can be 2S cm at 300 °C. The temperature dependence is shown in Figure 1.20. In the development of a sodium-sulfur battery P-alumina was used as the electrolyte membrane separating sulfur and liquid sodium. 

T. Oshima, M. Kajita and A. Okuno (2004) International Journal of Applied Ceramic Technology, vol. 1, p. 269 - Development of sodium-sulfur batteries . 

Once the principles of operating in a molten salt environment have been grasped, suitable extrapolations or interpolations of materials requirements and cell and equipment designs can be made between different systems. In bringing a molten salt process into commercial operation, unique materials problems requiring special solutions often limit its progress, but practically never prevent it. Thus, if a desired result may not be achieved for theoretical reasons in any alternative electrolyte, because of electrochemical instability, for example, then initial development costs and difficulties become inconsequential. Such has been the case with thermal batteries, " sodium-sulfur batteries, molten fluoride nuclear reactors, and molten carbonate fuel... 

The principle of operation is illustrated on Figure 4. The fast ion conductor 3-aluminium has been developed as the basic component of the sodium sulfur battery cell. Whether it will give birth to a new technological process is too early to predict. 

Oshima, T., Kajita, M., and Okuno, A. (2004) Development of sodium-sulfur batteries. Int. J. Appl. Ceram. Technol., 1, 269-276. 

A new generation of batteries is under development that has distinct advantages over the traditional lead-sulfuric acid batteries both in terms of weight and energy density, and which can be adapted to road or rail transport. Most attention to date has been applied to the sodium-sulfur battery, in which liquid sodium and liquid sulfur are separated by a diaphragm of )8-alumina. The cell is operated at 300-350°C, and the cell reaction is... 

However, the issue of the stability of power supply grids is not a new one. Electrochemical systems for energy accmnulation have been installed on the grid for over 20 years, with lead-acid or nickel-cadmimn batteries. More recently, we are witnessing a significant development of sodium-sulfur batteries (which are discussed in detail in Chapter 12). Experiments have been performed with redox flow systems (also detailed in Chapter 12). The unitary powers range from several MW to several tens of MW, and the quantities of energy stored from several MWh to tens of MWh. 

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