RECENT ADVANCES IN THE DEVELOPMENT OF SODIUM-SULPHUR BATTERIES FOR LOAD LEVELLING AND MOTIVE POWER APPLICATIONS

Abstract

—This paper describes some recent progress in the design and development of sodium/sulphur batteries for motive power applications. The historical development of cell designs over the last 10 yr is reviewed, and includes a discussion of development problems such as the durability of beta-alumina, and corrosion of the sulphur electrode current collector. The tubular electrolyte is now widely adopted as the preferred development option, and a computer analysis shows that a volumetric energy density of about 200 Wh/litre can be obtained in an optimum design of a battery including thermal insulation. An advanced cell design has been adopted in which sodium is fed into the anodic reaction zone by a capillary wick. This design is well suited to the demands of motive power applications in which the stored energy has to be supplied at about the 2 h rate. The design also permits the use of large electrolyte tubes, at least 30 mm dia × 500 mm in length, and this reduces the battery manufacturing costs. A large number of experimental cells have been tested, and over 85% utilization of the sodium and sulphur active materials has been achieved for repeated cycling of developed electrode constructions.