The occurrence of fires in electric vehicles (EVs) is less common than their combustion engine counterparts, in total number, but also in terms of the rate per miles traveled. However infrequent, it is extremely important to protect the vehicle’s occupants and prolong the time for a fire to exit the battery pack for as long as possible. The key method of achieving this is the proper choice and deployment of fire protection materials throughout the battery pack. The rapidly growing EV market across segments beyond just cars such as buses, trucks, vans, scooters, and motorcycles all present great and varied opportunities for material suppliers to enable safer battery packs.
IDTechEx’s report ‘Fire Protection Materials for Electric Vehicle Batteries 2023-2033’ analyses trends in battery design, safety regulations, and how these will impact fire protection materials. The report benchmarks materials directly and in application within EV battery packs. The materials covered include ceramic blankets/sheets (and other non-wovens), mica, aerogels, coatings (intumescent and other), encapsulants, encapsulating foams, compression pads, phase change materials, and several other materials. Ten-year market forecasts are included by material and vehicle category.
Variety in battery design and evolution
The EV market has yet to converge on a single battery design at any level; one only has to consider the cell format where prismatic took around 55% of the car market in 2021 with the rest split fairly evenly between cylindrical and pouch. The thermal management strategy also varies between manufacturers, with cold plates beneath the cells being the most popular option, but sidewall-cooled and air-cooled batteries also present significant adoption. Many manufacturers are also moving towards a cell-to-pack design where module housings (and a host of other materials) are removed, leading to improved energy density but potentially more challenging thermal runaway propagation prevention. These design choices all greatly impact the choice and deployment of fire protection materials and hence are covered in IDTechEx’s report to aid in determining material demands.
Many materials are applicable for fire protection in EV batteries. Source: IDTechEx report ‘Fire Protection Materials for Electric Vehicle Batteries 2023-2033’.
Ceramic blankets have been a common choice to provide protection above the cells and below the lid and to delay the propagation of fire outside the pack. In recent years, we have seen many adopt thick mica sheets to provide fire protection and excellent electrical isolation. Aerogels are not a new material, but their application within EV batteries has largely been limited in volume and constrained to China. However, major player Aspen Aerogels has secured a supply agreement with GM for its Ultium battery pack, moving the technology to the US. The use of encapsulating foams has also seen significant adoption for cylindrical cell battery packs with the likes of Tesla, to provide lightweight thermal insulation and structure. For pouch cells, compression pads are commonplace to accommodate cell swelling and many are now combining this functionality with fire protection to provide a multifunctional solution. There are a host of materials in addition to the ones mentioned above that can aid in the safety of battery packs by preventing the propagation of thermal runaway and/or containing fire events. The variety of battery design philosophies presents opportunities for many fire protection materials and their suppliers; in fact, IDTechEx is predicting a 13-fold increase in yearly demand for fire protection materials in EV batteries by 2033 in comparison to 2022.
Developments in safety regulations
Many will be aware that China was an early adopter of thermal runaway specific regulations, with, among other requirements, a need to prevent fire or smoke exiting the battery pack for five minutes after the event occurs. This standard was mandated from the start of 2021 and whilst a formal mandate similar to this is yet to be applied in other regions, OEMs have started targeting this, or are implementing more stringent requirements in their designs, to pre-empt future regulations and improve overall safety.
The EV market in India has exhibited a large transition in safety. In 2022, several fires in electric scooters were exhibited and many recalls issued. The governing bodies have now set adjustments (to take place from October 2022) to the current standards to include more of a focus on EV battery safety in micromobility segments. In addition to only using approved cells, battery design features like inter-cell spacing are also stated. The increasingly safety-focused regulations across multiple global regions mean that the focus on safety and materials that aid in that goal will become increasingly utilized across vehicle segments, although the choice and application of these materials will vary between the vehicle category and battery design. Whilst the vehicle segments outside of automotive are important, IDTechEx’s research shows that the combination of relatively large batteries and huge unit volumes sees electric cars accounting for over 90% of the fire protection materials market for EVs by the end of the decade.