Systematical electrochemical study on the parasitic shuttle-effect in lithium-sulfur-cells at different temperatures and different rates

The influence of cycling rate and temperature on the performance of lithium sulfur batteries is systematically studied by evaluating data of hundred identical cells. Differences in the discharge and charge capacities and the voltage profiles during the first and subsequent cycles are evaluated quantitatively in detail. Special attention is paid to the parasitic shuttle effect and its magnitude as function of C-rate and temperature. Mathematical models by Kumaresan et al. and Mikhaylik et al. are used to discuss the correlation between discharge/charge capacities, cycling efficiency and cycling rate at different temperatures. Mathematical error analysis further provides information on typical deviations between identical samples that can be expected when characterizing Li/S cells. This error can become significant especially when reaching higher cycle numbers. When changing the cycling parameters we find that the different regions of the voltage profile are affected differently. Therefore, we conducted first galvanostatic intermittent titration technique (GITT) measurements on the Li/S cell system to study the kinetics during cell cycling and evaluated the relaxation behavior between the different states of discharge/charge and OCV conditions. Significant differences in relaxation kinetics are found for the lower and higher plateaus of the discharge- and charge voltage profiles. (C) 2014 Elsevier B.V. All rights reserved.