ARTICLE Multifunctional hybrid polymer nanocomposites for automotive-battery packaging Joung Eun Yoo 1 | Victor Roev 1 | Joonho Bae 2 | Du-Seop Yoon 1 | Sung-Dug Kim 1 | Eun-Sung Lee 1 1 Materials Center, Samsung Advanced Institute of Technology, Suwon-Si, Kyunggi-Do, South Korea 2 Department of Nano-physics, Gachon University, Seongnam-si, Kyunggi-Do, South Korea Correspondence Eun-Sung Lee and Eun-Sung Lee, Materials Center, Samsung Advanced Institute of Technology, Suwon-Si, Kyunggi-Do 16678, South Korea. Email: eslee1@hotmail.com (E. -S. L.) and Sung-Dug Kim Email: doug.kim91@samsung.com (S. -D. K.) Abstract Global sales of new electric vehicles (EV) already passed a million units last year. Lithium-ion battery packs are composed of cells and assembly of modules. Never- theless, the development of light-weighted with high oxygen and moisture bar- rierability remains one of the untouched issues in battery technology. This study aimed to fabricate multifunctional hybrid nanocomposites for barrier films for Li- ion battery packs on electric vehicles applications. The synthesized carbon supported MgO nanoparticles (hereafter referred to as CSMO) were dispersed in high density polyethylene (HDPE) polymer to satisfy several requirements for EV battery packs. The loading amount of MgO was achieved up to 22 wt % of carbon, and the size distribution was in the range of 50 to 100 nm. The hybrid nanocomposites were characterized by water-vapor transmission rate (WVTR), various spectroscopic methods, thermo-gravimetric analysis and elemental analy- sis. Mechanical properties were also tested. The extremely low WVTR value of CSMO/HDPE composites below 0.5 mgm -2 day -1 is the lowest value among any other gas barrier films reported in the literature. Suitable mechanical properties were also achieved. The newly proposed multifunctional hybrid nanocomposites would be very promising for barrier films on automotive packaging applications. 1 | INTRODUCTION Lithium-ion (Li-ion) battery packs are composed of cells and assembly of modules. For an electric vehicle (EV) application of Li-batteries, packaging technology should be strictly complied with several requirements, such as high permeation barrier against moisture and oxygen, high mechanical stability, and thermal resis- tance. [1] In addition to these conditions for the safety and reliability, it is of most importance to reduce the weight of battery packs that can enhance the power consump- tion and long cycle life of EV battery packs. An innova- tive approach was proposed on the light-weighted battery pack, which is a multicell packaging with polymer encap- sulation, instead of an aluminum single cell packaging. In order to realize the light weighted Li-battery packs, the properties of polymer composites should be competi- tive to those of aluminum metal case, such as water vapor transmittance rate (WVTR), mechanical (impact and tensile) strength, and thermal conductivity. A lot of efforts have been attempted to apply soft exter- nal case to reduce thickness and lighten weight of Li-ion battery packs since 1998 [2] ; however, it has not been suc- cessful because the polymer composites showed relatively high gas permeability and low thermal conductivity com- pared with those of metal or metal oxide. Inorganic nano- platelets dispersed in polymer matrix significantly improved mechanical property, thermal stability, and barrier property of polymer nanocomposites. [3] High aspect ratio inorganic fillers including exfoliated clay, mica flake, or expanded graphite are very effective on making not only mechanically toughening but also improving gas impermeability of Received: 24 September 2019 Revised: 4 January 2020 Accepted: 23 January 2020 DOI: 10.1002/app.49059 J Appl Polym Sci. 2020;e49059. wileyonlinelibrary.com/journal/app © 2020 Wiley Periodicals, Inc. 1 of 9 https://doi.org/10.1002/app.49059