How does Mica Sheet protect EV batteries from thermal runaway?

How does Mica Sheet protect EV batteries from thermal runaway?

Mica has high-insulating properties and is even used for protecting furnaces. It can withstand temperatures up to 1000℃ and voltages up to 2000V. It absorbs little moisture and is resistant to most elements making it ideal for the thermal insulation of EV batteries.

Mica sheets and laminates can be used to separate cells in an EV battery and even keep it away from the rest of the vehicle. They are available as sheets of varying thicknesses and are placed in between the cells of the battery. The insulating properties of mica prevent the propagation of the reaction throughout the storm and prevent further damage before it can be controlled.

While you cannot absolutely eliminate the possibility of thermal runaway, these mica sheets can slow down the process and somewhat reduce the possibility.

These sheets can improve the thermal properties of the battery pack and can be used to design batteries that can charge faster without overheating.

Advantages of mica sheet over other materials for thermal runaway protection

Other materials like Silicon, Nomex, and polyester films like Mylar, Lumirror, and Hostphan have been used extensively in EVs for thermal insulation. But their temperature range is limited compared to Mica. Phlogopite Mica can maintain its structural integrity up to 1200℃ and muscovite mica can maintain up to 1000℃.

Compared to this, other insulation materials can maintain their integrity up until around 500C only. But of course, their role in limiting thermal runaway is different. For example, phase-change materials are often used to cover the cells of the battery. If the battery heats up, the material absorbs the heat, turns it into liquid, and later into gas, and the gas then carries the heat out of the battery pack.

Thermal runaway protection in battery packs for EVs depends on multiple factors. Most batteries come with a battery management system that controls the rate of charging to prevent overheating. Components like silicon and Nomex insulate other parts of the battery. And mica is used for better heat dissipation, and in case of thermal runaway, to slow it down.

Types

According to different mica plate:

◆ H1: Hard mica plate

◆ H2: Hard mica plate

According to varying degrees of surface smoothness:

◆ H1:Muscovite smooth plate

◆ H2 :Phlogopite smooth plate

Properties for mica plate

Relative to general insulation material, the prominent advantages of the flexible mica plate are:

◆ Excellent insulating properties at high temperature: At 500-1000℃ operating ambient temperature, the voltage breakdown resistance is 15KV/mm;

◆ Good tensile property: It can be processed into a variety of shapes without layer separation;

◆ Excellent environmental protection performance: The product contains no asbestos, and has less smoke and odors, even smokeless and odorless when heating;

◆ Excellent acid and alkali resistance, and oil resistance.

Availability for mica plate

Thickness: 0.1mm 0.15mm 0.2mm~100mm

Length×Width: 1000×600mm 1000×1200mm 1000×2400mm

Note: The product less than 2.0mm thickness can be formed by stamping. The products larger than 2.0mm shall be processed by turning, milling, drilling and other processes.

FQ’s material technician has the experience to understand the Rubber Seal information and design challenges fully and will cooperate with you honourably Our long working experience with Ev battery parts will allow us to suggest some ideal materials and configurations for assembly.

Application Case: Mica Sheet for EV Battery Pack