Thermal runaway prevention – Latent Heat Carbon protects battery modules

The Operating Principle—Phase Change as a Protection Mechanism

Phase-change materials absorb large amounts of thermal energy—known as latent heat—during the transition from solid to liquid without the temperature rising further. This effect can be precisely controlled: The melting point of the PCM determines the temperature at which protection becomes active. For LHC70, this melting point is 70 °C, and the enthalpy of fusion is 195 J/g. The specific heat capacity is 1.7 J/g·K at a density of just 0.9 g/cm³—which makes Latent Heat Carbon particularly attractive for weight-critical mobile applications. 
By integrating the PCM into a highly conductive graphite matrix, the absorbed heat is not only stored locally but is also rapidly distributed throughout the entire component—with a thermal conductivity of 15 W/m·K in the x and y directions. This prevents heat from accumulating at a single point and spreading to adjacent cells.

Proven Effective – Nail Penetration Test

Schunk Carbon Technology has demonstrated the effectiveness of Latent Heat Carbon cell holders for cylindrical cells in nail penetration tests. In this standard test designed to simulate thermal runaway, a fully charged 18650-type NMC cell is mechanically penetrated by a nail, triggering a thermal reaction in the cell. 
The result: Only the penetrated cell caught fire. The LHC70 cell holder absorbed the released thermal energy so effectively that no adjacent cell was adversely affected. The fire was extinguished after a few seconds—and the thermal event was completely contained after just 11 seconds.

Two Functions—One Component

The LHC cell holder for cylindrical Li-ion battery cells fulfills two tasks simultaneously within the battery module. During normal operation, it ensures even temperature distribution across the entire module—the high thermal conductivity of the graphite matrix prevents local temperature spikes that would accelerate cell aging. In the event of a fault, it acts as a thermal barrier: The PCM absorbs the energy from the affected cell before it can spread to neighboring cells. 
Schunk Carbon Technology manufactures Latent Heat Carbon in customer-specific geometries—tailored to the respective cell size, module architecture, and requirements.