How To Choose Flame Retardant Materials for New Energy Vehicles？

How to Choose Flame Retardant Materials for New Energy Vehicles？

Outline

I. New Energy Vehicle Lightweight Trend and Its Demand for Flame Retardant Materials

II. Flame Retardant Requirements for Automotive Interior Materials and Interpretation of LOI

III. Selection and Application of Flame Retardant Materials for Battery Modules

IV. Flame Retardant and Safety Considerations for Charging Facilities

V. Material Requirements and Commonly Used Materials for Automotive Connectors

VI. Special Requirements and Material Selection Criteria for Automotive Cables

I. New Energy Vehicle Lightweight Trend and Its Demand for Flame Retardant Materials

One of the most critical trends brought about by the rapid development of the automotive industry is lightweight, and nowadays the use of various modified plastics, composites and lightweight alloys is becoming more and more mature, and more and more plastics are appearing in more and more places, whether on traditional oil vehicles or new energy vehicles.

The difference between new energy vehicles and fuel vehicles is that electricity is used as the driving power source, so the safety of electricity is particularly important. Once a short circuit or high voltage breakdown occurs, the parts will stop working, which may cause the car to break down, the whole car leakage, or cause spontaneous combustion.

These power-related automotive components in the choice of materials in addition to insulation voltage, but also need to focus on the consideration of flame retardancy.

II. Flame Retardant Requirements for Automotive Interior Materials and Interpretation of LOI

Automotive interior categories are numerous, can be roughly divided into four categories: fiber textile and leather, plastic, rubber, composite materials.

These materials are flammable or combustible materials, in the event of a fire in the vehicle, the burning of the interior materials will cause direct harm to the vehicle occupants, so the flame retardant automotive interiors have a great significance for safety.

When it comes to the flame retardancy of automobile interiors, we have a parameter we can't get around, which is LOI (Limit Oxygen Index), i.e. Limit Oxygen Index.

LOI Limit Oxygen Index, refers to the specified conditions, the specimen in the oxygen, nitrogen mixture in the gas stream, to maintain the balance of combustion required for the lowest oxygen concentration, expressed as a percentage of the volume of oxygen.

The limiting oxygen index is a way to evaluate the relative combustibility of plastics and other molecular materials, which is very effective in determining the degree of combustion when the material is in contact with the flame in the air, and has therefore been emphasized by countries all over the world, and China has long promulgated the corresponding national standard of oxygen number method.

The high limit oxygen index indicates that the material is not easy to burn and the low oxygen index indicates that the material is easy to burn. It is generally believed that the oxygen index <22 belongs to flammable material, the oxygen index between 22~27 belongs to combustible material, and the oxygen index >27 belongs to refractory material.

III. Selection and Application of Flame Retardant Materials for Battery Modules

Currently, there is no uniform vehicle voltage standard in the world, and major new energy vehicle enterprises use different voltages. Vehicle enterprises like BYD use new energy vehicles with low, medium and high voltage platforms, with high voltage up to 690V and instantaneous pulses up to 800V or more.

If flame retardant materials are not used, once the voltage breakdown or high temperature, can lead to vehicle leakage or spontaneous combustion and other accidents. Therefore, flame-retardant materials have become the first choice for the battery module case. Battery pack shell can generally be used: cast steel, aluminum alloy, SMC composite materials (i.e. sheet molding compound), carbon fiber reinforced composite materials, long glass fiber flame retardant reinforced polypropylene materials.

Plastic shell has a better cost advantage as well as comprehensive performance, is currently the main development of power battery shell development materials. After the clear flame retardant requirements for power batteries, more and more companies began to use flame retardant plastics for battery shells.

IV. Flame Retardant and Safety Considerations for Charging Facilities

Charging facilities include high-voltage components such as charging piles, high-voltage cables, high-voltage connectors and charging guns. Their importance is the same as the power battery in the vehicle, and they all need to be considered in terms of flame resistance and safety of charging.

However, the standards for charging facilities are not yet fully consistent. Due to the different voltage platforms of different electric vehicles, coupled with the different interfaces, communication protocols and other technical factors, this directly leads to the inability to interconnect between piles and piles, and the problem of vehicle-pile mismatch is very prominent.

Charging gun as electric vehicle charging connector, is connected to the charging pile and other charging facilities and electric vehicles “bridge”, the quality of the good and bad directly affect the charging performance and safety. Charging gun material requirements are relatively high, common materials are: PBT + GF, PA + GF, weathering PC and so on.

The materials of socket plugs are mainly glass fiber reinforced PBT, PA66 and so on.

V. Material Requirements and Commonly Used Materials for Automotive Connectors

Relays, high-voltage connectors and other connectors contact parts are metal, the number of insertion and extraction is high, the most basic requirement is that the material has a good flame retardant, and heat-resistant, to avoid fire.

Currently the connector commonly used materials are PBT, PPS, PA, polyphenylene ether (PPE), PET, liquid crystal polymer (LCP) and so on.

VI. Special Requirements and Material Selection Criteria for Automotive Cables

Different from the traditional wire and cable, automotive cable because it has the special characteristics of the application environment, the material has very high requirements. In addition to ensure that the insulation at the same time also have a certain high temperature resistance, aging resistance, and in the combustion of halogen-free flame retardant and low smoke density.

Note: XLPE is cross-linked polyethylene, TPE is thermoplastic elastomer, TPV is dynamic cross-linked thermoplastic elastomer, TPU is thermoplastic polyurethane elastomer, EPR is ethylene-propylene rubber, PVC/HNBR is polyvinyl chloride/hydrogenated nitrile butadiene rubber, and CPE/CR is chlorinated polyethylene/chloroprene rubber.

In the selection of flame retardant materials for new energy vehicles, YINSU Flame Retardant is actively developing a wide range of high-performance flame retardants to meet market demand. These innovative products include red phosphorus and piperazine flame retardants applied to PP, as well as high-impact red phosphorus and antimony complex flame retardants for ABS materials. These flame retardants are not only suitable for battery modules and automotive interior parts, but are also widely used in key components such as connectors and cable sheathing, providing higher safety and reliability for new energy vehicles.