The enthalpic reaction limits of Li-ion battery chemistries within various operating regimes and environments

Abstract

Ensuring the safety of Li-ion battery packs is crucial due to their widespread use in various applications. Li-ion batteries fail catastrophically, and dense packaging increases the risk of failure propagation. To design safe battery packs that prevent propagating failures, the energetics of battery failure must be well-defined for the operating conditions and selected battery chemistry. Experimental failure testing of every battery chemistry and cell size is cumbersome and labor-intensive. This study theoretically calculates failure energetics for: (i) closed failures and (ii) open failures. Calculations are based on the component masses within the cell, including the cathode, anode, and electrolyte. Failure Energies (kJ) are normalized and reported based on the Electrical Energy content (kJ) of the cell, R_FE/EE. The calculated R_FE/EE values for a lithium iron phosphate (LFP) battery are (i) 1.10 and (ii) 21.76, which agree with experimental studies. For open system failures, the calculated R_FE/EE for the nickel manganese cobalt (NMC) cell is 13.85 and for the lithium cobalt oxide/NMC (LCO/NMC) cell it is 10.21. While the LFP chemistry is considered safe, its safety is highly dependent on the failure conditions making it critical to keep Li-ion battery packs in inert enclosures to diminish the severity of failure.