Exothermicity analyses and energy efficiency of a novel liquid cooling strategy in suppressing thermal runaway propagation of a lithium-ion battery module

Abstract

Thermal runaway propagation (TRP) within lithium-ion battery (LIB) modules has been extensively explored in existing studies, whereas quantitative analyses of exothermic feature of LIBs during TRP and energy efficiency of the related suppression systems are insufficiently investigated. To challenge this issue, a novel liquid cooling system consisting of six n-shaped cold plates is designed to suppress TRP in a LIB module. Effects of mini-channel width (w, 3–12 mm) of cold plates, coolant flow velocity (u, 0.01–0.03 m/s), and type of coolant (mixture of glycol and water with varying glycol mass fractions of 20 %, 50, 80 %, referred to as GS20, GS50, GS80) on cooling performance are examined by developing a 3D numerical model which is verified by experimental measurements. The results show that u= 0.01 m/s delays onset time and peak temperature of TR but fails to suppress TRP regardless of w and coolant type. With fixed u of 0.02 m/s and GS50, cooling performance can be classified into three regimes: (1) TRP region where 3 mm≤w≤ 6 mm; (2) transition region where 6 mm<w< 8 mm and TRP is partially prevented; (3) Non-TRP region where 8 mm≤w. When u= 0.03 m/s, similar phenomena are observed differing in critical w values. Transient heat release rate (HRR) and total released heat (TRH) of a representative LIB as well as the transient nondimensional concentrations and HRRs of the four elemental components in LIB are calculated to quantitively reveal the exothermicity. HRR of LIB exhibits a bimodal feature with the first small peak contributed by decomposition of SEI and the second main peak being ascribed to the other three reactions. LIB temperature, pressure drop, and a new parameter, energy efficiency factor, are analyzed to identify an optimal cooling solution.