MODELING A POROUS INTERCALATION ELECTRODE WITH 2 CHARACTERISTIC PARTICLE-SIZES

A mathematical model of a complete cell containing a porous intercalat ion electrode with two characteristic particle sizes is presented. Gal vanostatic cycling and relaxation phenomena on open-circuit are compar ed to a cell with a single particle size. Electrodes with a particle-s ize distribution show modestly inferior capacity-rate behavior in all cases considered in this work. The cycling results exhibit a mismatch in the states-of-charge of the surfaces of the different particle size s located at the same position in the electrode. The magnitude of this mismatch correlates with the slope of the open-circuit potential vs. state-of-charge curve of the intercalation material. The relaxation on open circuit is substantially faster when the particles are uniformly sized. Asymptotic solutions were developed to aid in the description of the open-circuit behavior in the cases with nonuniform particle siz es. The particle-size distribution has a more pronounced influence on the open-circuit results than on the galvanostatic results.