Electric vehicle (EV) fire safety continues to be a critical topic. Data continues to support the fact that EVs are less likely to catch fire than internal combustion engine vehicles. However, as a new technology, EVs get more press, and besides, even a very low occurrence rate still poses significant risks to vehicle occupants and surroundings. Effective thermal management, quality control, and battery management systems minimize the risk of thermal runaway occurring, but fire protection materials are the primary method of either preventing the propagation of thermal runaway or delaying its progression long enough to meet regulations and provide safety for occupants.
IDTechEx's report on Fire Protection Materials for Electric Vehicle Batteries analyzes 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, polymers, and several other materials. 10-year market forecasts are included by material and vehicle category.
Whilst automotive markets provide the largest battery demand, there are large opportunities for material suppliers in other vehicle segments such as buses, trucks, vans, 2-wheelers, 3-wheelers, and microcars. Some of these smaller vehicle sectors present an even greater risk to owners, as they are often charged or kept inside the home.
Variety in battery design and evolution
Various cell formats and battery structures are used in the EV market. In 2024, 60% of new electric cars sold used prismatic battery cells, with pouch cells accounting for 17% and the rest using cylindrical. Each of these cell formats has different needs in terms of inter-cell materials which has led to trends in fire protection material adoption. For example, cylindrical systems have largely used encapsulating foams, whereas prismatic systems typically use materials in sheet format such as mica.
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: Fire Protection Materials for EV Batteries
The market for fire protection materials is becoming increasingly crowded, with a wide range of materials and suppliers available. IDTechEx's material database covers over 150 materials from 72 suppliers. Each of these have more or less suitable applications, and the major categories are benchmarked in the report in terms of thermal conductivity, density, cost, and cost in the required application volume.
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. Mica sheets are another popular choice with excellent dielectric performance at thin thicknesses between cells but are often used in thicker sheets above modules. Aerogels are continuing to see market progress with significant adoption in China, but also now globally with adoption from GM, Toyota, and Audi to name a few.
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 several material suppliers are starting to combine this functionality with fire protection to provide a multifunctional solution.
Polymer suppliers are making a big push to provide major components of the battery pack with fire-retardant polymers, inter-cell spacers, or even polymers with intumescent properties. These have the potential to be lighter, more customizable in geometry, and lower cost than metals and fire protection materials combined.
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 5 minutes after the event occurs.
The regulations are generally struggling to keep up with the rate of technology development. The UN ECE regulation continues to be revised, and is getting steadily closer to formalization. Whilst the specific targets are still in flux, it is very likely that detection of thermal runaway will be required, followed by an "escape time" for vehicle occupants. The 5-minute escape time is unlikely to be sufficient for future regulations and more effective thermal runaway propagation measures will be necessary. Therefore OEMs have started to target longer escape times in order to pre-empt future regulations and improve overall safety. Other factors like gas management, the impact of flooding, and low conductivity coolants are all likely to be considered in future. However, regulations tend to set a goal and are technology agnostic, leading to a large variety of potential material solutions.
IDTechEx's report discusses the regulations that are currently in place and those being discussed. These feed into IDTechEx's market forecasts showing a greater adoption of fire protection materials per vehicle. However, this must be paired with trends around battery development that can often reduce material use per vehicle. The variety of battery designs and material solutions presents a large opportunity across several markets and suppliers. IDTechEx predicts this market will grow at 15% CAGR from 2024 to 2035.
Key Aspects
Overview and evolution of:
- Electric vehicle fires and thermal runaway
- Electric vehicle recalls related to fires
- Regulations in different global regions
Material analysis and trends including thermal conductivity, dielectric strength, density, and more for:
- Ceramics (and other non-wovens)
- Mica
- Aerogels
- Coatings (intumescent and other)
- Encapsulants
- Encapsulating foams
- Compression pads (with fire protection properties)
- Phase change materials
- Polymers as fire protection materials
- Other material categories
10 year market forecasts & analysis:
- EV battery demand for cars, buses, trucks, vans, scooters, and motorcycles (GWh)
- Cell-to-cell protection by material (kg)
- Pack-level protection by material (kg)
- Total fire protection by material (kg)
- Total fire protection by material (US$)
- Total fire protection by vehicle category (kg)
- Total fire protection by vehicle category (US$)
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