Experimental study on cycle aging of 3.4 Ah lithium-sulfur pouch cells: Temperature and current investigation

Abstract

High energy density sulfur cathodes are among the most promising alternatives to conventional intercalation cathodes for next-generation lithium-ion batteries. However, the practical implementation of lithium-sulfur (Li-S) systems is limited by rapid capacity fade and poor cycling stability. These issues are primarily driven by the polysulfide shuttle effect, wherein soluble higher lithium polysulfides, generated at the high voltage discharge plateau, migrate between the electrodes, resulting in active material loss. In an attempt to approach the commercial application of Li-S batteries, an in-depth investigation of pouch cells under different conditions is inevitable. This study focuses on the cycle aging of pre-commercial 3.4 Ah Li-S pouch cells at different temperatures and current rates using non-destructive techniques. The most negative effect on the performance of the Li-S battery cell is a low temperature of 10 degrees C and 50 degrees C. From the perspective of different charging and discharging currents, the reduced battery lifetime was observed for fast charging at 0.2 C and 0.3 C. The internal resistance increased with the degradation of the battery cell and is more pronounced in the low voltage plateau. To maximize the cycle life of the Li-S batteries, the optimal cycling conditions are at around 30 degrees C, charging at 0.1 C and discharging at 0.2 C.