Influence of Internal and External Factors on Thermal Runaway Characteristics of Lithium-Ion Batteries Induced by Dual Heat Sources: An Experimental Research

Abstract

Localized overheating is a common application fault in lithium-ion batteries (LIBs) and a significant trigger for thermal runaway (TR). The application scenarios involving multi-point synchronous heating have made the induction of LIB TR behavior by dual heat sources a research hotspot. Both internal battery conditions and external heat source conditions influence TR behavior. This study systematically investigates and analyzes experimental results from two aspects: internal battery conditions (cathode material type and state of charge (SOC)) and external heat source conditions (arrangement of dual heat sources and heating power). The research findings indicate that SOC and cathode materials are critical factors influencing thermal safety. At 100% SOC, the peak TR temperatures for NCM811, NCM523, and LFP batteries are 762.2 °C, 687.2 °C, and 379.4°C respectively, whereas at 25% SOC, these temperatures decrease by 258.3 °C, 227.2 °C, and 146°C respectively. Changes in heat source arrangement and heating power primarily affect the heat conduction rate, impacting the triggering time of TR. TR in NCM batteries is accompanied by flame jetting behavior, with the largest peak flame area of 4415 cm2 observed in 100% SOC NCM811 batteries. The primary components of particulate matter in TR eruptions are carbon and metal oxides, with internal battery conditions being important factors influencing the composition of erupted particles. The severity of TR is linked to mass loss, with NCM811 batteries experiencing the highest mass loss due to the combustion of more materials, indicating greater fire risk. The research results provide important scientific references for improving the theory of LIB TR, guiding TR and fire prevention and control, and formulating relevant standards.

Keywords: Lithium-ion battery, Dual heat sources, Flame dynamics, Heating power, State-of-charge