AC Impedance Analysis of 20 Ah Lithium-Ion Cell for Stationary Applications

Introduction Extended diffusion of battery energy storages will be critical issues for exploded wind power generation (WPG) and photovoltaic (PV) system in the electricity grid within several years. Sodium sulfur (NaS) battery is now the only one compatible system from the viewpoints of battery capacity, production level, and price. However, the commercialized NaS system had been optimized for low-rate (C/8) load levering use and not optimized as high-rate operation. Lithium-ion battery has higher potential than that of NaS system from the viewpoints of a wide rate capability, room temperature operation, and low standby power and so on. However, limited operation life is important issue to be improved. We reported about long cycle operation using demonstration pattern for the combination with WPG and PV. The degradation factor during cycle and storage operation was determined using AC impedance analysis.