Thermal propagation

Example

Use in Lemonergy

Connect mechanisms with appropriate test evidence.

This is a reference concept. No executable Lemonergy block has been verified for this term.

Connected concepts

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Module

A group of cells connected in series and parallel, mechanically held together with its own voltage and temperature sensing, built as the unit from which a pack is assembled and serviced. Cell-to-pack designs do away with it.

Thermal propagation test

Triggering thermal runaway in one cell of a module or pack — by heater, nail or overcharge — and measuring whether and how fast it spreads. Regulations now require at least a warning period, five minutes in several markets, before the cabin is at risk.

Thermal barrier

An insulating sheet — aerogel, mica, ceramic fibre or intumescent material — placed between cells or modules to slow heat transfer during a thermal event and buy time for occupants to leave.

Thermal runaway

Self-accelerating heating in a cell: heat speeds up reactions that release more heat, until the cell vents, catches fire or ruptures. An internal short, overcharge or external heating can trigger it.

Venting

The controlled release of gas and vapour from a cell whose internal pressure has risen too far, through a vent designed to open before the case bursts. The vented gas is flammable and toxic, so packs route it away from occupants.

References & further reading

Technical references

1. Thermal runaway mechanism of lithium ion battery for electric vehicles: A review

   Xuning Feng et al. · Energy Storage Materials · 2018

   Technical reference · Electrical, mechanical and thermal abuse; thermal-runaway mechanisms and propagation.