Mica products are increasingly utilised as critical thermal runaway protection materials in power batteries for new energy vehicles (NEVs). This is driven by the heightened safety concerns related to thermal runaway incidents, where excessive heat within the battery can lead to fires or explosions. As batteries’ energy density rises, manufacturers face the urgent technical challenge of enhancing battery safety.
In this context, flame-retardant mica plays a significant role in various components of battery systems, including battery packs, modules, top covers, individual cells, and busbars. It is used primarily for thermal insulation between cells, ensuring that heat from one does not propagate uncontrollably to others.
Mica’s performance is highly valued due to its exceptional insulation capabilities, even under extreme temperatures ranging from 500°c to 1200°c. Additionally, mica materials possess other desirable properties, such as:
- Good mechanical strength (bending strength and hardness)
- Chemical resistance (acid and alkali resistance)
- Aging resistance
- Ease of fabrication into different shapes
- No toxic emissions when exposed to high heat
Compared to other materials, such as aerogel felt, flame-retardant foam, and ceramic silicone rubber, mica stands out as the primary material for thermal isolation between cells in batteries. Its application significantly enhances the safety and reliability of power batteries in New Energy Vehicles (NEVs).
The mica advantages in New Energy Vehicles are as follows:
1. High voltage resistance
Mica tape exhibits excellent high-voltage resistance (20 kv/mm). Mica products can ensure the reliable operation of the entire battery system. Voltage stability is a critical parameter in the power battery system. Mica material is resistant to high voltage. It will not cause material damage due to high voltage, which can affect battery performance.
There are similar application cases. Mica tape is a standard material for fire-resistant cable that can pass the BS6387 standard test, as it can withstand a 950℃ flame for 180 minutes without compromising circuit integrity.
2. High temperature and fire resistance
The power battery will generate a significant amount of heat while in operation, and under normal circumstances, internal cooling devices will dissipate the heat promptly. However, if an unexpected situation arises in which the heat cannot be dispersed, it accumulates to a certain extent and may lead to thermal runaway and even fire. Mica material exhibits sound thermal insulation and UL94 V-0 flame retardant properties, effectively reducing the risk of thermal runaway in the battery. Even in extreme cases of fire, the mica material can effectively prevent the spread of fire inside the battery.
3. Good processing performance and adaptability
Because the internal space of the power battery is limited, filling the internal materials is a complex process, and the materials must be able to adapt to various irregular surfaces. Soft mica materials, such as mica rolls, possess high softness and are easily cut to fit multiple irregular shapes within the battery surface, ensuring an optimal heat dissipation effect. Rigid and moulded mica plates possess good mechanical properties. They can be processed into various shapes, making them suitable for use as battery bottom plates, cover plates, and baffles, among other applications.
4. Lightweight
With the increasing demand for a driving range for new energy vehicles, the design of lightweight bodies and vehicle components has become a key development direction. Therefore, the power battery is the mostcriticalt component of new energy vehicles, lightweight design to meet the weight and size of the battery is smaller at the same time, ensuring sufficient power, performance, and safety. Mica material has low density, even lower than Aluminum, which can reduce the weight of the power battery, reduce the material cost, and improve the power battery life.
Overall, mica’s combination of high voltage resistance, thermal and fire resistance, adaptability, and lightweight properties makes it a valuable material for enhancing the safety and performance of power batteries in new energy vehicles.
