6 Materials for electrical and thermal insulation of batteries and accumulatorsJohn Moot
The importance of electrically powered vehicles is growing: climate protection, dwindling fossil fuels and an increased demand for mobility due to rising population figures require new solutions and alternative drive systems.
Electric vehicles can make a significant contribution to protecting the environment and reducing emissions. That is why electric vehicles are an integral part of the technology-open drive strategies of German manufacturers and suppliers. The leap in battery technology has made electromobility an option for future mobility.
Developers have focused on exploiting the existing advantages of electric motors over internal combustion engines. This is, for example, the high efficiency of an electric motor.
The lithium-ion batteries used in electric vehicles are being continuously improved. Car manufacturers are developing more powerful lithium-ion batteries that have a longer range and can be recharged more quickly. Along with these improvements, improving safety is becoming more urgent in the development of electric vehicles.
Lithium-ion batteries generate a significant amount of heat during operation and charging. In addition to using thermal management materials to dissipate the heat, placing protective, flame-retardant insulating materials between the battery cell, module and battery components can provide further thermal and electrical insulation protection.
Materials must be used in the following areas:
- Insulation gaskets on positive connectors
- Cell insulation
- Insulation of serial connectors
- BMU insulation
- Edge protection
- Battery sheathing
- Battery insulation
- Case insulation
The following 6 materials are used for electrical and thermal insulation of batteries and accumulators:
- Polypropylene film
- Polyester film
- Flame retardant 3M FRB
- Nomex aramid paper
- Polyimide film
1. polypropylene film for electrical and thermal insulation of batteries and accumulators
Polypropylene has excellent dielectric properties, excellent impermeability and is easily formable. Formex is the first choice for engineers and designers. It is very durable and has excellent dielectric strength. It is also flame retardant (UL94 V-0) and meets stringent safety and environmental requirements. Formex can be die-cut, scored and folded to create a customized dynamic 3D shape.
2. polyester films for electrical and thermal insulation of batteries and accumulators
Polyester films (also known by the trade names Mylar and Hostaphan) are also used in many applications where electrical insulation, thermal resistance and dimensional stability are required. PET films are useful as a dielectric insulator over a relative temperature range. Another product may be more suitable for higher temperatures depending on the application within the battery.
3. Flame Barrier FRB inorganic insulation papers for electrical and thermal insulation of batteries and accumulators
3M Flame Barrier FRB inorganic insulation papers are based on inorganic material technology, specifically designed for use as flame barriers in electrical equipment. 3M FRB insulation papers provide excellent resistance to flammability and ignitability, excellent arc, creepage path and dielectric breakdown resistance, and good thermal conductivity to protect electrical hazards.
4. Nomex aramid papers for electrical and thermal insulation of batteries and accumulators
Nomex aramid papers have long been used in electrical applications. Nomex, which is based on meta-aramid fibers. This material is indispensable for manufacturers of motors, transformers or generators. In addition to its dielectric performance, it is characterized by very high thermal resistance (220°C according to UL 746) and mechanical strength. Properties that are also important in the manufacture of accumulators and batteries.
5. polyimide films for electrical and thermal insulation of batteries and accumulators
Polyimide films are widely used in applications exposed to extreme heat and vibration. Polyimide films are flame retardant (UL94 V-0) and maintain their electrical, chemical and mechanical properties even under extremely harsh conditions.
6. mica for electrical and thermal insulation of batteries and accumulators
Mica is a mineral material found in the composition of some insulating films. Because it is very crumbly, mica “flakes” can be added to a binder. This mixture is then applied to a substrate to produce what we call flexible mica. It can also be added directly during the manufacture of a film, as is the case with Nomex Type 818. Mica increases dielectric performance and provides thermal barrier properties. This makes it particularly suitable for insulation between cells.
All materials can be supplied as die-cut and with a self-adhesive layer.