The application prospects of powder coatings on electric vehicles and key points of electrical insulation design

The global transportation sector is accelerating the process of electrification. During the period from 2020 to 2021, the market for new energy vehicles showed a counter-trend growth. In 2020, the sales of new energy vehicles increased to 3 million units, accounting for 4.1% of the total vehicle sales; in 2021, the sales further doubled to 6.6 million units, accounting for nearly 9% of the global automotive market. The market share increased by more than twice compared to two years ago, even in the context of chip shortages; all the net growth in global vehicle sales came from new energy vehicles.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Under this trend, models with high-voltage electrical components such as HEV, PHEV, EREV, and pure electric vehicles have gradually become the design mainstream. The voltage range of the high-voltage battery system covers 200V to 800V, and the electrical insulation design in a compact space has become the core focus of the industry.

The insulation design of batteries directly relates to the operational safety of electric vehicles. According to the GB/T18384 standard for electric vehicle safety requirements in China, it is divided into three parts: the on-board energy storage part, functional safety and fault protection, and personnel electric shock protection. It proposes clear regulations for the electrical safety of electric vehicles, ensuring that the vehicle will not cause harm to users and the surrounding environment during normal use and possible failure scenarios. Depending on the different ways of electric shock protection after insulation failure, electrical components can be classified into four categories, and each category of components has clear insulation protection characteristics requirements.

In the battery system, insulation design is the basic core requirement. Many domestic car manufacturers and battery enterprises have already selected powder coatings as the preferred solution for internal insulation of batteries. Compared with the traditional blue film insulation method, the powder coating spraying process is more suitable for 100% automated production requirements of battery modules and can effectively improve insulation reliability. In the battery module production line, through fully enclosed automated spraying and installing insulation membranes, the insulation performance between battery cells can be ensured. At the same time, by combining advanced technologies such as plasma cleaning and intelligent optical inspection, the stability of the production process and product quality can be further guaranteed. This is also a key technical support for the transition from the traditional module era to the CTP era.

The demand for insulation powder coatings for cylindrical battery cells stems from their own structural characteristics. The positive electrode potential of aluminum shell batteries is higher than the shell potential, and the shell potential is higher than the negative electrode potential. If the shell comes into contact with the negative electrode, a corrosion reaction will occur, causing the aluminum shell to flake off. To avoid such problems, the shell is usually connected to the positive electrode to increase the shell potential and achieve anti-corrosion protection, which makes the battery cell itself charged and requires external insulation means to achieve isolation from the outside world. Powder coatings are the ideal material that meets this demand.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

As an environmentally friendly and high-performance material, powder coatings were first introduced into the insulation field of battery cells from Europe. It has the advantages of convenient construction and one-time spraying to form. It is convenient for the installation and transportation of battery cells. Compared with traditional blue films, powder coatings do not create air gaps, have stronger adhesion, and are less prone to damage, which can effectively simplify the development difficulty of structural connections between battery cells and the Pack in the CTP era.

 

At the same time, powder coatings have excellent insulation performance, outstanding anti-corrosion performance, resistance to high and low temperature shock, and can meet the long-term usage requirements of high-voltage electrical components for electric vehicles. Powder coatings are widely applied in the electrical ecosystem of electric vehicles, covering battery cells, internal structural components of battery packs, thermal management systems, battery shells, connector bars, aluminum bars, and other components, as well as charging facilities and energy storage facilities. Most of these components have long-term heat resistance requirements, and the protective effect of powder coatings can effectively extend the service life of components and the entire vehicle.

The core value of applying powder coatings in the battery system of electric vehicles mainly lies in three aspects: First, it helps prevent the risk of thermal runaway and battery failure in electric vehicles, ensuring vehicle operation safety; Secondly, it can establish more sustainable manufacturing processes, facilitating the realization of highly reliable automated production. Thirdly, it complies with strict international environmental regulations and directives, does not contain volatile organic compounds (VOCs), does not generate hazardous waste, and the oversprayed powder can be recycled and reused, possessing significant environmental advantages.

The specific application of powder coatings in key components of electric vehicles is as follows: In the battery system, dedicated insulating powder coatings can achieve the insulation function between battery cells, featuring excellent insulation strength, outstanding adhesion, and good cold and hot shock performance, while also providing multiple protections such as thermal management, electrical insulation, flame retardancy, corrosion resistance, and chemical resistance for the battery housing; In the cooling separators and cooling pipelines, special-formulated powder coatings can enhance the operational efficiency of the battery cooling system, achieving excellent electrical insulation effects with higher insulation strength, providing superior edge coverage and dense coating coverage, and epoxy-based powder coatings can meet UL94 V-0 flame retardancy, UL746B 130°C long-term heat resistance requirements, while also having excellent physical impact resistance and corrosion resistance.

In the application of busbars, busbar systems have gradually replaced a large number of high-voltage cables. Through fluidized bed or electrostatic spraying processes, insulating powder coatings can be easily applied to nickel-plated, silver-plated, tin-plated, or bare copper wires and aluminum busbars, namely Epoxy Powder Coated Busbars, which can effectively enhance the heat dissipation of the busbars, reduce the ignition load, and extend the service life of the busbars under thermal shock conditions.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Such powder coatings for busbars can meet multiple certification requirements, such as UL1446, UL94 V-0, and UL746B, with a relative temperature index RTI of up to 130°C, meeting the core performance requirements of Insulated Copper Bus Bar. Among them, tinned copper busbars after powder coating can further enhance the insulation protection capability, adapting to the requirements of high-voltage scenarios in electric vehicles, and the busbar insulation paint type also becomes an important choice for busbar insulation design.

In conclusion, with the continuous advancement of the electric and intelligent processes of electric vehicles, powder coatings, with their advantages of environmental protection, excellent insulation performance, and compatibility with automated production, have broad application prospects in the electrical insulation field of electric vehicles. They not only meet the insulation protection requirements of key components such as battery systems, cooling systems, and busbars, but also conform to the development trends of industry environmental protection and production efficiency improvement, providing reliable guarantees for the electrical safety of electric vehicles, and also promoting the technological upgrading and application expansion of related products such as Epoxy Spray Copper Bus Bar.