Suppression of lithium-ion battery thermal runaway propagation by silica aerogel sheets with different aerogel gel contents and thicknesses

Thermal runaway (TR) propagation in lithium-ion battery (LIB) modules can increase fire hazards and damage electric vehicles. The incorporation of thermal insulation materials effectively mitigates heat transfer during TR propagation in a module. This work explores the relationship between the thermal insulation ability of a silica aerogel sheet (SAS) and the intensity of the TR of a LIB. Accelerating rate calorimetry (ARC) characterizes thermal runaway behavior in commercial prismatic lithium-ion batteries spanning LFP to NCM 811 energy densities. The intrinsic safety of a battery is related to its energy density, and among the examined batteries, NCM 811 exhibited the most violent TR. Two kinds of SASs with different aerogel gel contents (80 kg m⁻³ vs. 120 kg m⁻³) were synthesized via a sol‒gel approach followed by supercritical fluid drying and are referred to as SAS-A and SAS-B. Both SAS-A and SAS-B showed similar thermal insulation performance at 675 °C, whereas SAS-B showed better thermal insulation performance than SAS-A at 900 °C. The application of SAS-A successfully suppressed TR propagation in the LFP, NCM 111 and NCM 523 modules. Moreover, SAS-B can easily suppress TR propagation in the NCM 622 and NCM 811 modules. The appropriate aerogel content and thickness of the SAS should be considered based on the relationship between the severity of the TR of the LIB and the thermal insulation performance of the SAS. The SAS provides a new solution for the safer design of battery thermal management systems.