Electrical and Structural Characterization of Large-Format Lithium Iron Phosphate Cells Used in Home-Storage Systems

Abstract

This article presents a comparative experimental study of the electrical, structural, and chemical properties of large-format, 180 Ah prismatic lithium iron phosphate (LFP)/graphite lithium-ion battery cells from two different manufacturers. These cells are particularly used in the field of stationary energy storage such as home-storage systems. The investigations include 1) cell-to-cell performance assessment, for which a total of 28 cells are tested from each manufacturer; 2) electrical charge/discharge characteristics at different currents and ambient temperatures; 3) internal cell geometries, components, and weight analysis after cell opening; 4) microstructural analysis of the electrodes via light microscopy and scanning electron microscopy; 5) chemical analysis of the electrode materials using energy-dispersive X-ray spectroscopy; and 6) mathematical analysis of the electrode balances. The combined results give a detailed and comparative insight into the cell characteristics, providing the essential information needed for system integration. The study also provides complete and self-consistent parameter sets for the use in cell models needed for performance prediction or state diagnosis.