In Depth Battery Aging Analysis: A Key to Sustainable Energy Storage in Microgrids

The increasing use of renewable energy makes balancing generation and demand in power systems more challenging. This has led to a growing focus on battery technologies and energy storage solutions. These systems are essential for the effective integration of renewable energy into sustainable power networks. However, most experimental studies of lithium-ion batteries are limited to deep charge and discharge cycles, which do not fully represent how batteries operate in stationary applications. In these applications, batteries experience not only the main charge and discharge processes but also additional stress from current fluctuations due to the variable nature of renewable energy. These smaller cycles, known as micro-cycles, have a depth of discharge of less than 2% and occur alongside the primary charge and discharge processes. This paper presents the results of an experimental study focused on battery aging, considering micro-cycles that emulate real-world conditions for batteries in microgrid storage systems. It demonstrates that the degradation in storage systems occurs differently when compared to deep charge and discharge cycles. It provides a detailed analysis of the degradation processes occurring in microgrid batteries using EIS diagnostics and post-mortem analysis and demonstrates the applicability of the findings for renewable energy systems.