Cycling Decay Mechanism and Accelerated Aging Model of Sulfur-Based Lithium-Ion Batteries
Sulfur-based lithium-ion batteries, particularly those employing sulfurized poly(acrylonitrile) (SPAN) cathodes and graphite (Gr) anodes, offer high theoretical capacity and low cost but suffer from temperature-dependent capacity decay. This study systematically investigates the electrochemical dynamics and capacity decay mechanism of SPAN||Gr pouch cells cycled at 25–55 °C. Multiscale analyses reveal that capacity fade arises from active lithium loss and increased resistance, both accelerated by higher temperatures. Active lithium loss is primarily attributed to dead lithium formation and thickening of the solid electrolyte interphase (SEI) and cathode electrolyte interphase (CEI), while resistance increase is predominantly due to SEI/CEI thickening. As temperature rises, active lithium loss becomes the dominant decay factor. Leveraging the consistent decay mechanism across temperatures, an accelerated aging model based on the Arrhenius equation is developed: y = 0.9x + a. This model accurately predicts cycling parameters at specific temperatures and reduces testing time by 50% when extrapolating from 55 °C to 25 °C. These insights provide critical guidance for developing long-life sulfur-based batteries for practical energy storage applications.