Cathodes soluble

Figure 18. Discharge mechanism of a Li—SOCij ceii. The cell can operate until the surface of the carbon cathode is fully covered by electronically insulating LiCI and S discharge products. The Li—SO2 cell is also a soluble cathode system with a cell construction similar to that of the Li—SOCI2 cell. It follows a similar discharge reaction where the reaction product is L1S204.

The reaction of lithium with the electrolyte to form a surface film significantly modifies its behaviour. On the one hand, the film confers chemical stability and useful shelf life on the system. On the other, it is responsible for greatly depressed exchange currents and the consequent phenomenon of voltage delay, as discussed in Chapter 3 in connection with magnesium aqueous batteries. It is convenient to discuss separately film formation with insoluble and with liquid and soluble cathode systems. 

Cells with liquid or soluble cathodic reagents... 

The formation of passivating films on lithium in contact with liquid or soluble cathodic reagents is a prerequisite for the construction of a practical cell. The film acts in the same way as a separator, preventing further direct chemical reaction of lithium and the cathodic reagent. However, film formation involving the action of S02, SOCl2, etc. on lithium is considerably more complex and may produce much more severe voltage delay characteristics than in the case of insoluble cathodes described above. 

All the currently available commercial lithium cells using a soluble cathodic reagent are based on sulphur dioxide. These advanced cells, which have outstanding performances but also certain drawbacks, have until fairly recently been limited to military uses. Now they are finding increasing service in a wider civilian market for heavy duty applications. 

Li/S02 Cells Lithium/sulfur dioxide cells (Li/SC>2) are perhaps one of the most advanced lithium battery systems. They belong to the soluble cathode cells category. Liquid SO2 is used as cathode a lithium foil is used as anode, and lithium bromide dissolved in acetonitrile is used as electrolyte. The active cathode material is held on an aluminum mesh with... 

Soluble-cathode lithium primary batteries most times contain very toxic cathodes and flammable solvents. These types of batteries are seldom seen outside of the military in sizes larger than a button/coin cell. They are common in some heavy industrial or remote processes including oil-drilling operations. They are extremely common in many military forces throughout the world. 

The electrolytes are less reactive than most soluble-cathode primary batteries. Sulfur dioxide, thionyl chloride and sulfuril chloride are extremely toxic and quickly fume when exposed to moisture (forming very acidic mists). 

Make sure fire extinguishers are accessible, clearly marked, and are the correct class for the types of fires anticipated. Graphite powder based extinguishers are the correct class for lithium primaries and can also be used for lithium ion. Copper fire extinguishers should not be used for soluble-cathode lithium primary batteries. Make sure personnel are familiar with extinguisher locations. 

Flat discharge curve. Lithium primary cells with soluble cathode reactants typically show a flat discharge curve which provides constant power output. 

Long storage time. Because the Li metal in this class of cells is passivated by the soluble cathode reactant in storage, long shelf lives of 10-20 years are achievable. 

Lithium Primary Cells with Soluble Cathode Reactants... 

Secondary Al-SnClg and Al-FeQz cells were made using a 1 2 acidic MeaPhNCl/Aiaa melt in the anode compartment and the same electrolyte with the soluble cathode in a cathode compartment separated from the anolyte by a... 

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