Electrochemical performance of lithium/sulfur cells with three different polymer electrolytes

Charge and discharge characteristics of lithium/polymer electrolyte/sulfur cells are presented. Three different electrolytes were studied, and cells w ere operated at temperatures ranging from ambient to about 100 degrees C. T he effects of the sulfur electrode composition and cycling regimen on both the potential profiles and the capacity fade rate were investigated. Cells prepared with poly(ethylene oxide) (PEO) and operated at 90-100 degrees C c ould be discharged to nearly the full theoretical 1672 mA h/g active materi al but with a high rate of capacity fade. Reducing the depth of discharge t o 30% or less increased the cell lifetime. Room-temperature cells with poly (ethylene glycol) dimethyl ether could be discharged to about 45% utilizati on of the sulfur and showed a much lower capacity fade rate after the secon d cycle. Several possible explanations for the high rate of capacity fade a nd the effect of the depth of discharge on this rate are presented. (C) 200 0 Elsevier Science S.A. All rights reserved.