With the boom of electric vehicles, the structure of battery pack has been improved a lot, from module-pack to “Cell To Pack”, refer to “CTP”. It will decrease structural complexity, reduce overall weight of battery pack, increase energy density per unit volume and range, thus requiring a material combining two significant functions of thermally conductive and structural bonding, namely thermally conductive structural adhesive.

At present, it’s not easy to get such a thermally conductive structural adhesive with high reliability. You can find PU based products in the market, but it never is the right solution for battery cell bond due to poor reliability. Why no engineers used it in battery pack instead of thermal gap pad or thermal gap filler in the past several years? because the performance and reliability of PU attenuate a lot in the next four to five years according to simulation of ageing test, It may lead to car recall event in practical application.

To avoid this problem, GLPOLY has abandoned PU technical roadmap and developed a new material-modified epoxy based thermally conductive structural adhesive. This is a new technical roadmap far surpassing PU or epoxy based products.  From the perspectives of thermal conductivity, hardness and shear bond strength, we can see the differences between GLPOLY modified epoxy based thermally conductive structural adhesives and PU or epoxy based products.

Here are some test instructions:

1. Thermal conductivity. A/B component 1:1 mixed in volume, curing in 24 hours at room temperature. Specimens in Dia30X2.0mm are placed in ageing test chambers at 125 Celsius degree for 1000hours and in hygrothermal ageing chamber at 85 Celsius degree, RH85% for 1000hours. After testing, thermal conductivity of specimens will be tested to find the difference before and after test.

2. Hardness. Check the hardness directly after thermal conductivity test has been completed.

3. Shear bond strength. One end of two Al bars are overlapped and bond by thermally conductive structural adhesive, after ageing test, we test the bond strength by mechanical properties tester.

GLPOLY thermally conductive structural adhesives are performance and reliable with data change less than 10% before and after test and has the features and advantages:

1. GLPOLY thermally conductive structural adhesive has 8MPa bonding strength, almost twice stronger than PU based products, enduring extreme temperature cycling test from -45~175 Celsius degree without crack;

2. Flammability UL94 V-0, goes out when leave the fire;

3. Service temperature -45~175 Celsius degree, short term: 250 Celsius degree;

GLPOLY thermally conductive structural adhesives have been validated by EV customers and battery manufacturers such as AIWAYS Motor, Lixiang Motor, Xiaokang Motor, LISHEN Battery and more, and have been introduced for mass production.

GLPOLY has collaborated with many leading enterprises in each industry, such ahs GAC Motor, Lixiang Motor, NIO Motor, LG, DJI, DT Mobile etc, providing advanced thermal interface materials to protect their brand reputation for performance and reliability.