A carbonate/H2O2 surrogate for representing thermal runaway and state-of-charge effects in lithium-ion battery fires

Abstract

For fire hazard assessment of lithium-ion batteries (LIBs), the autoignition of carbonate/H 2 O 2 mixtures in a transient constant-volume reactor was numerically simulated to investigate their potential as simplified reactive surrogates for selected LIB fire characteristics. The effects of replacing air with hydrogen peroxide as the oxidizer on the ignition behavior of carbonate fuels, the autoignition and rapid self-heating behavior of the carbonate/H 2 O 2 surrogate at elevated initial temperatures, and the feasibility of phenomenologically representing state-of-charge (SOC)-dependent thermal behavior were systematically investigated. Compared with carbonate/air mixtures, the ignition delay times (IDTs) of carbonate/H 2 O 2 mixtures were reduced by enhanced reactivity. Reaction-pathway and sensitivity analyses of DMC/H 2 O 2 , employed as a representative single-carbonate fuel, revealed that OH was the primary radical promoting ignition, whereas HO 2 played an increasingly important role as the mixture became more fuel-rich. Comparison with the ARC measurements was used to identify phenomenological equivalence-ratio bounds associated with the thermal behaviors of fully charged and fully discharged LIBs. These results suggest that the proposed carbonate/H 2 O 2 surrogate provides a simple reactive framework for examining selected thermal-runaway and SOC-related characteristics of LIB fires.