Why use mica tape?
- High electrical insulation: Mica’s dielectric properties block high voltages (typically tens of kV across a few millimeters), preventing short circuits between cells and pack rails.
- Extreme heat tolerance: Mica tape survives very high temperatures (some grades up to ~1000 °C). This lets it buffer overheated cells and act as a heat sink, protecting surrounding materials during thermal events.
- Flame retardant: Many mica tapes achieve UL 94 V-0 flame ratings, meaning they self-extinguish and resist fire propagation. Their inorganic structure does not burn and does not undergo any contact with the cell.
- Thermal runaway mitigation: By lining the battery pack or cell barriers with mica tape, the spread of heat from a venting cell can be slowed. In effect, it serves as a fireproof shield that helps limit the severity of a thermal runaway cascade.
- Easy application: Mica tapes are often backed with high-temperature pressure-sensitive adhesive, allowing them to bond securely to steel or aluminum pack surfaces. This simplifies assembly (eliminating the need for fasteners) while maintaining the tape’s insulation and flame-resistant properties.
Standards and safety compliance
Mica tapes are formulated and tested to meet strict EV safety standards. They are routinely assessed under flammability and insulation tests. For example, adhesives and composites containing mica are designed to satisfy UL 94 V-0 (plastic flame) ratings. Tapes are also evaluated for dielectric breakdown (per ASTM D149 or IEC methods) to ensure they hold off the pack’s working voltage. In practice, battery assemblies using mica insulation help OEMs comply with regulations (such as UL 2202 for EV battery systems) because the materials themselves inhibit fire and withstand abuse. Highmica certifies that their mica tapes comply with RoHS/REACH environmental regulations, ensuring both chemical safety and electrical performance.
## Applications in EV battery systems
Mica tape is used at multiple points in a battery pack. It lines metal housings and module covers, insulating the cells from grounded pack plates. It also wraps around copper busbars and high-voltage connectors to prevent arcing. Inside the module, layers of mica tape can serve as barriers or between-cell spacers to slow heat transfer. In some designs, manufacturers even wrap entire module assemblies in a mica-lined fire sleeve. Typical example applications include battery case lids and floors, busbar insulation, and inter-module fire walls.
In summary, mica tape is a critical insulation material in EV battery packs. Its combination of extreme-temperature endurance, high dielectric strength, and flame resistance helps EV manufacturers meet safety requirements. By installing mica tape in the pack design (on housings, busbars, connectors, etc.), engineers can contain faults and thermal events, improving the overall reliability and compliance of high-voltage battery systems.