EFFECT OF LOAD AND OPERATIONAL TIME ON THE PERFORMANCE OF LITHIUM-ION BATTERIES

Abstract

Lithium-ion (Li-ion) batteries have attracted significant global attention due to their widespread applications in portable electronic devices, electric vehicles, and renewable energy storage systems, largely because of their high energy density and long cycle life. Despite these advantages, their performance and longevity are highly influenced by operational stresses such as load intensity and duration of use. This study investigated the effects of load and operating time on the performance of Li-ion batteries using three load conditions: 100 W (light load with a target discharge duration of 15–30 minutes), 200 W (moderate load with a discharge duration of 30–45 minutes), and 300 W (heavy load designed to achieve approximately 1 Ah ±10% consumption), while monitoring performance over operating times ranging from 0 to 60 minutes. The results showed that under light load conditions, the batteries maintained a relatively stable output voltage of approximately 12 V with minimal variation, indicating stable electrochemical behaviour and low internal stress. However, under moderate load conditions, polarization and internal impedance increased gradually with time, leading to a progressive voltage decline to about 8–7 V and a noticeable reduction in efficiency. When subjected to heavy load, the batteries experienced rapid voltage drop to approximately 7 V, accompanied by increased electrochemical and thermal stress that accelerated performance degradation. The findings also revealed a nonlinear interaction between load intensity and operating duration, meaning that prolonged operation at moderate loads could produce degradation effects similar to those caused by short periods of heavy loading. The dominant degradation mechanisms identified included solid electrolyte interphase (SEI) thickening, electrolyte decomposition, particle cracking within electrodes, and lithium plating. Overall, the study highlights that repeated moderate-to-high load cycling significantly shortens battery cycle life and emphasizes the importance of implementing advanced battery management systems incorporating current regulation, optimized depth-of-discharge control, and effective thermal management strategies.