Now, Jun Lu and co-workers report a switchable thermal-responsive interlayer that regulates thermal runaway in battery modules. This thermal-switching-material (TSM)-based interlayer provides a high thermal conductivity during normal operation and prevents heat propagation at high temperatures to mitigate thermal runaway. The interlayer consists of temperature-sensitive polymer microspheres and layered two-dimensional (2D) graphene. The highly conductive graphene network ensures sufficient thermal conductivity during normal operation, but when the temperature reaches the microsphere expansion threshold, the microspheres expand rapidly, separating adjacent 2D graphene layers and disrupting the heat transport pathways.
The composite thermal-responsive interlayer was characterized via various thermal measurements to understand the resulting spatial and temporal temperature distributions. The interlayer demonstrated a thermal conductivity of 1.33 W m–1 K–1 below 80 °C, shifting to a thermally insulating state of 0.1 W m–1 K–1 within 30 s once a temperature of 100 °C is reached. In thermal dissipation tests, the surface maximum temperature of the lithium-ion batteries containing the thermal-responsive interlayer was 20 °C lower than that of the control group using a commercial aerogel interlayer (62.6 °C). Furthermore, the temperature variation across the battery module was 13 °C for those with the thermal-responsive interlayer compared with 37 °C for those with commercial aerogel interlayers.
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