Primary lithium batteries with solid cathodes

Table 2.5 Primary lithium batteries with solid cathodes...

Lithium primary batteries with liquid cathodes are a relatively mature technology. Incremental improvements in capacity and performance may occur through design modifications and the use of new materials such as improved carbons in the passive cathode. The U.S. Army is adopting Lithium/Manganese Dioxide replacements for some of the Lithium/Sulfur Dioxide Batteries listed in Table 1 in certain applications. These replacements provide higher capacity and energy at room temperature but not at lower temperature. See the chapter on Lithium Primary Cells Solid Cathodes in this work. 

As seen in the previous section there are numerous types of lithium batteries. In this section, we shall look at the generic hazards of primary (with liquid or solid cathode) and rechargeable batteries. There is much controversy over the reactivity of several individual chemistry types. It is the authors opinion that there are inherent hazards associated with any battery type or energy source and in most situations the hazards and size are directly related. In a similar scenario, lithium batteries in general cannot be categorized into being more or less hazardous than any other chemistry without knowing the exact type and size of the systems to be compared. 

Solid Electrolytes. A protected Lithium anode is under development for both primary and secondary batteries that promise much larger capacities. This strategy is illustrated by the Li/seawater primary battery in which a Lithium anode is immersed in a nonaqueous electrolyte, the anolyte, that is separated from seawater contacting a cathode current collector by a Li -ion solid-electrolyte separator. The seawater acts as a liquid cathode. Except for contact with a negative post, the Lithium anode and its anolyte are sealed in a compartment containing a Li -ion solid-electrolyte wall that interfaces the seawater. The anolyte is chemically stable to both the Lithium and the solid electrolyte the solid electrolyte must not be reduced on contact with the Li anode. Moreover, eiflier the seal or the compartment must be compliant to allow for the change in volume of the Lithium on discharge. The seawater is not ccmtained in an open cell, it is contained within a battery in a closed cell. The LF ions from the anode react with water at the cathode current collector ... 

Lithium-Metal Salt secondary batteries are analogous to the Lithium-seawater primary battery [3]. A Li -ion solid electrolyte separates a nonaqueous anolyte and an aqueous cathode. For example, a Lithium anode with a carbonate anolyte and an aqueousFe(CN)g /Fe(CN)g cathode has been shown to give aflat voltage F 3.4 V with an efficiency that increases with the molar ratio of iron cyanide in the cathode solution [27]. This promising approach requires development of a Li-ion solid electrolyte having a (Tli > 10 8/cm at room temperature that is stable to an acidic cathode solution and is not reduced by contact with a Li° dendrite on the anode side. 

Primary Battery Design, Fig. 3 (Lithium) Wound layers of cathode coated onto a metal current collector with a solid Li foil anode which also serves as a current collector. High rate - newest construction... 

Lithium-air batteries [28] may also use a solid separator that will block dendrite growth from the anode to the cathode but allows permeation of the Li" ion between an anolyte and a catholyte. The simplest such separator would be a solid Li -ion solid electrolyte, but a porous glass containing the liquid electrolyte has been used where the anolyte and the catholyte are identical. As in the Zn-air primary battery, a porous carbon containing an oxygen-reduction catalyst on the pore walls and the liquid electrolyte in the pores provides the structure needed to facilitate the catalytic reaction of Li" ions with the gaseous O2 cathode. The cathodic reaction... 

---