Moderated nitridation of Al nanoflakes into open-pore composites for battery enclosures with improved crash and fire resistances

摘要

Aluminium alloys and carbon fibre composites are up-and-coming lightweight materials for the functional enclosures of electric vehicle batteries. However, the emergence of high-power density batteries is drawing attention to safety concerns in crash-generated fire accidents, where these materials lose stability, potentially leading to battery explosions. Here, we present insights into the physical-chemical formation of an open porous Al composite with advanced crash absorption capacity and unique resistance to fire impacts. The nacre-like structure of this composite originates from the moderated nitridation of Al nanoflakes in low-purity nitrogen. This method allows a uniform (flawless) densification to the desired microstructure before the optimally open pores become closed. Apart from the elevated level of the energy absorption capacity in the optimal composite, the open pores allow rapid oxidation in the air at high temperatures so that its structure shrinks/expands evenly, less than 1%. The mechanism of this form-stability is controlled by the reactions of the interpore Al layers with oxygen and water vapour. (C) 2020 Elsevier B.V. All rights reserved.