Dynamic Aspects of Solid Solution Cathodes for Electrochemical Power Sources

Battery systems based on alkali metal anodes and solid solution cathodes, i.e., cathodes based on the insertion of the alkali cation in a "host lattice," show considerable promise for high energy density storage batteries. This paper discusses the interaction between battery requirements, in particular for vehicle propulsion, and electrochemical nd constructional factors. It is argued that the energy obtainable at a given load is l imited by saturation of the surface layers of cathode particles with cations, and that the time before saturation occurs is determined by diffusion of cations and electrons into the host lattice. Expressions are developed for plane, cylindrical, and spherical particles, giving the relation between battery load and the amount of cath-ode material utilized before saturation. The particle shape and a: single pa-rameter Q is used to describe cathode performance. Q is the ratio between dis-charge time at 100 % utilization of the cathode at the given load, and the time constant for diffusion through the cathode particles. This description is ex