Aging Characteristics of Stationary Lithium-Ion Battery Systems with Serial and Parallel Cell Configurations

The significant market growth of stationary electrical energy storage systems both for private and commercial applications has raised the question battery lifetime under practical operation conditions. Here, we present a study two 8 kWh lithium-ion (LIB) systems, each equipped with 14 lithium iron phosphate/graphite (LFP) single cells in different cell configurations. One system was based on standard configuration connected series, including cell-balancing 48 V inverter. other featured novel stacks parallel connection seven each, no system, 4 were operated as part microgrid continuous cycling mode between 30% 100% state charge, solar-storage day–night cycling. aging characteristics terms capacity loss internal resistance change determined by disassembling regular checkups characterizing individual well-defined laboratory As main result, showed cell-averaged losses 18.6% 21.4% serial configurations, respectively, after 2.5 years 810 (serial operation) 881 (parallel cumulated equivalent full cycles. This is significantly higher than reference cycled conditions at 20 °C, which only 10% 1000