Molten-salt-electrolyte battery development

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. 

U.S. Air Force Academy in 1961. He was an early researcher in the development of low-temperature molten salts as battery electrolytes. At that time low temperature meant close to 100 °C, compared to many hundreds of degrees for conventional molten salts. His work led directly to the chloroaluminate ionic liquids. 

In order to increase the share of renewables in the world s energy consumption, an important challenge for the nearest years is the development of cheap electrochemical devices for stationary electricity storage. Recent work has shown that molten salt electrolytes provide an attractive option. Sadoway and co-workers have indeed proposed a battery comprising a negative electrode of Mg, a molten salt electrolyte (MgCl2-KCl-NaCl), and a positive electrode of Sb, which operates at 700 °C [22]. Its big advantage over... 

The early history of ionic liquid research was dominated by their application as electrochemical solvents. One of the first recognized uses of ionic liquids was as a solvent system for the room-temperature electrodeposition of aluminium [1]. In addition, much of the initial development of ionic liquids was focused on their use as electrolytes for battery and capacitor applications. Electrochemical studies in the ionic liquids have until recently been dominated by work in the room-temperature haloaluminate molten salts. This work has been extensively reviewed [2-9]. Development of non-haloaluminate ionic liquids over the past ten years has resulted in an explosion of research in these systems. However, recent reviews have provided only a cursory look at the application of these new ionic liquids as electrochemical solvents [10, 11]. 

E. J. Casey (Defense Research Establishment, Ottawa) reviewed the selection of anodes and electrolytes for high-energy density storage batteries. The present state of development of batteries by using light metal anodes in nonaqueous, molten salt and solid electrolytes was reviewed, and suggestions were made on the feasibility of novel systems. 

In this section we discuss three types of advanced batteries with molten salts LiAl/LiCl-KCl/FeS, LiAl/LiCl-KCl/FeS2 and Li4Si/LiCl-KCl/FeS2. They all derive from the initial battery developed at the Argonne National Laboratories in the United States [360-364], In the battery type Li/LiCl-KCl/S, both reactants and the electrolyte are in the molten state. The overall cell reaction is... 

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 lithium/iron sulfide rechargeable battery system is another high-temperature system and must be operated above 400°C so that the salt mixture (LiCl-KCl) used as an electrolyte remains molten (see Chapter 41). The negative electrode is lithium, which is alloyed with aluminum or silicon, and the positive electrode can be either iron monosulfide or iron disulfide. No development is being performed on these technologies at this time because room temperature battery systems are showing comparable performance. 

---