Impact of Temperature and Current Rate Protocols on the Aging of Lithium-Ion Batteries from Capacity Testing and Impedance Analysis

<div class="section abstract"><div class="htmlview paragraph">This study looks into the impact of temperature on the aging of lithium-ion batteries, which are an important component of energy storage systems in electric vehicles. To evaluate battery capacity over time, experiments were carried out at two temperatures, 25°C and 50°C, imitating real-world vehicle circumstances. Pristine cells were initially assessed in terms of capacity and internal resistance.</div><div class="htmlview paragraph">Aging results from cycling indicate that higher operating temperatures, particularly under aggressive conditions (fast charging), lead to accelerated battery degradation due to heat accumulation. Charging at 2C resulted in fast degradation at both temperatures, with the battery reaching its End Of Life (EOL), 80% capacity, in fewer than 200 cycles. Surprisingly, cycling at 50°C resulted in a longer lifespan than 25°C for 1C charge/discharge rates. The 1C charge and 2C discharge regimen at 50°C produced the best results, retaining more than 80% capacity even after 600 cycles. This shows that, given optimal cycling conditions, batteries can last longer, even at high temperatures. Electrochemical impedance measurement demonstrated an increase in ohmic resistance during cycling, notably at 50°C, indicating alterations at the electrode-electrolyte interface. Surface temperature measurements of the cells revealed higher peaks after 2C charging, indicating faster deterioration.</div><div class="htmlview paragraph">This study investigates the effect of aging on lithium-ion batteries under controlled temperature and C-rate settings, focusing on how increased temperatures and rapid charging promote deterioration. The findings offer useful information for optimizing heat management and charging methods, as well as improving battery longevity and performance in real-world electric car applications.</div></div>