New thermal insulation material for power battery cells
The important work at the power battery pack level of new energy vehicles is to build an effective protection system and configure various schemes and technologies to a design that is most suitable for oneself.
Due to the high density of mica plate and the fact that it is a rigid material that is not easily deformed, it is difficult to fully fit the battery; while aerogel is expensive and cannot withstand the high temperature caused by the explosion of the battery during thermal runaway.
It can be seen from the above that it is difficult for the existing battery protective materials to provide ideal and reliable protection. Once the battery catches fire or explodes, there is no reliable thermal insulation material for isolation, and it cannot effectively insulate and flame retardant. Therefore, in view of the above technical problems, it is necessary to provide a new thermal insulation material for power battery cells.
A large part of the passive protection work is passed on to component companies or material companies, who need to provide good explosion-proof products and fire-resistant insulation materials. The FoamTech modified melamine foam developed by Zhengzhou Fengtai Materials Co., Ltd. has a lower cost and better effect on inhibiting the spread of thermal runaway.
The product is made of melamine foam and ceramic fiber felt. The nano-scale voids inside the product can slow down heat conduction, provide the lowest thermal conduction value, and have excellent thermal shock resistance. The fiber mat can fully rebound after being compressed by 70%, can withstand the heavy pressure of thousands of times its own weight without breaking, and still has good resilience after thousands of compression cycles.
More importantly, this nano-sponge fiber felt can maintain good flexibility in butane flame and liquid nitrogen at 1500 °C, and the long-term use temperature is 1200 °C. Good stability at high temperature, not brittle. It can be used as a high-temperature thermal insulation gasket to prevent thermal short-circuits, gaskets at molten metal, and isolation (anti-sintering) materials.
Insulation layer arrangement in the battery pack
In addition to low thermal conductivity, the thermal insulation material used in the battery pack also needs to have the characteristics of flame retardancy, insulation, high temperature of soft bars and light weight.
FoamTech modified foam composite material is used as the thermal insulation layer of the battery pack. The shape of FoamTech modified melamine foam can be cut according to actual needs. Due to the irregular surface shape of the module in the battery pack, high-voltage copper bars and low-voltage wire harnesses are arranged around it. Therefore, the thermal insulation layer is pasted on the inner wall of the lower casing and the upper casing according to the shape.
Thermally responsive, ultra-strong, ultra-thin (1mm) flexible FoamTech modified melamine foam composites were prepared based on phase change materials for inhibiting high temperature thermal runaway of battery packs to suppress thermal runaway spread between cells. The modified material in modified melamine foam has reliable thermal conductivity under normal conditions and high thermal sensitivity at high temperature. After the thermal runaway occurs, the high temperature of the cell will cause the vaporization of the FoamTech modified melamine foam, which will absorb a large amount of heat and release a large amount of fire extinguishing agent.
The remaining FoamTech modified foam after the modified material is released has an ultra-low thermal conductivity of less than (0.02W/m.k), which can continue to prevent the transfer of heat between cells and inhibit system-level thermal runaway to a certain extent. Therefore, the battery pack with this modified melamine foam exhibits normal thermal management at normal operating temperature and a high ability to block thermal runaway under abnormal conditions. In addition, it has the characteristics of mass production, good processing performance and adjustable trigger temperature, which can be used to manufacture a series of advanced, safe and durable modified foam. Its application fields can even be expanded to oil tank emergency materials, space detection and firefighting equipment.
Conclusion and Outlook
In order to meet the strict requirements of the development trend of new energy vehicles for thermal management materials, Zhengzhou Fengtai Materials Co., Ltd. has launched a series of high-performance materials. These innovative high-performance foam are lighter in weight than metal, offer greater design flexibility than metal parts, and maintain long-term performance under high temperature and coolant conditions.
From a large number of experiments, it is known that the influence of temperature on the inside of the battery pack cannot be ignored! In order to reduce weight and cost, there is a continuous demand for material thinning and actual thermal insulation of accessories. However, this will bring new challenges to the reliability of materials and even heat transfer performance, which will also be solved by optimizing thermal insulation materials in the future.
At present, the power battery pursues high energy ratio, high safety and low cost, which puts forward higher requirements for the quality and safety of the battery assembly process. Whether it is a soft pack battery or a square battery, there are thermal insulation materials between the batteries. Due to various limitations, it cannot meet the requirements of flame retardant, acid and alkali resistance, light weight, high buffer performance, insulation and low cost at the same time.
FoamTech modified foam just achieves thermally triggered absorption, fire suppression and thermal insulation. The porous nature of FoamTech-based modified foam and the nano-scale voids inside can slow down thermal conduction, provide the lowest thermal conduction value, and resist thermal shock.
The high temperature resistance and ultra-low thermal conductivity (0.02W/m.k) of Foamtech modified melamine foam have a great influence on the thermal runaway propagation process of the battery. By analyzing the propagation process of thermal runaway, we found that under the thermal management conditions of FoamTech modified melamine foam, thermal runaway has the characteristics of “locality”. FoamTech modified foam can protect the cells in the battery module from heat The effect of high temperature caused by runaway.