China’s electric vehicle industry entered a new battery-safety phase on July 1, 2026, when the mandatory national standard GB 38031-2025, Electric Vehicles Traction Battery Safety Requirements officially took effect.
The significance goes beyond another round of laboratory testing.
The direction of battery safety is shifting from warning occupants after thermal runaway begins toward preventing a thermal event from developing into fire or explosion at the battery-system level.
That shift also changes how thermal insulation materials should be evaluated.
Instead of asking only:
How low is the thermal conductivity of this material?
Battery engineers increasingly need to ask:
Can this material help limit heat propagation from a failing cell and protect adjacent cells long enough to prevent escalation?
That distinction is particularly important for aerogel insulation sheets used as cell-to-cell thermal barriers.
What Changed Under GB 38031-2025?
The previous approach to thermal propagation placed significant emphasis on providing occupants with a thermal-event warning before fire or explosion.
GB 38031-2025 raises the safety objective considerably.
According to information published by Chinese government authorities, the updated thermal propagation requirements move from the previous requirement for an alarm before fire or explosion toward requiring the tested battery to not catch fire or explode during the specified test, while still providing an alarm.
Requirements concerning smoke hazards to occupants are also included.
The updated standard also introduces or strengthens several important safety evaluations, including:
- Battery bottom-impact testing, addressing damage caused by impact to the underside of a battery pack.
- Fast-charging-cycle safety testing, including an external short-circuit test after 300 fast-charging cycles.
- Stricter thermal propagation requirements.
- Expanded insulation-resistance requirements.
- Enhanced battery pack and system-level safety requirements.
These changes make one thing increasingly clear:
Battery safety is becoming a system-level engineering problem, rather than simply an individual material or cell property.
From Thermal Runaway to Thermal Propagation
Thermal runaway begins at the cell level, but the most serious battery-pack incidents occur when the event spreads.
A simplified failure chain can be expressed as:
Cell Failure → Thermal Runaway → Heat Transfer → Adjacent Cell Heating → Secondary Thermal Runaway → Pack-Level Propagation
Once one cell enters thermal runaway, intense heat can be transferred to neighboring cells through conduction, convection and radiation.
If an adjacent cell absorbs sufficient energy and reaches its own critical temperature, another thermal runaway event may occur.
The process can then continue through the module.
For this reason, the engineering challenge is not simply making individual components “fire resistant.”
It is about interrupting the propagation chain.
This is where cell-to-cell thermal barrier materials become particularly important.
Why Cell-to-Cell Thermal Barriers Matter
A thermal barrier is typically positioned between neighboring cells or critical components within a battery module.
Its purpose is not to eliminate thermal runaway completely.
Instead, the barrier helps reduce the rate of heat transfer from the failing cell to surrounding cells.
Even a delay can be valuable.
The longer adjacent cells remain below their critical temperature, the more opportunity the battery system has to prevent a localized event from becoming a cascading failure.
For battery designers, this creates several material requirements simultaneously.
1. Low Thermal Conductivity
Low thermal conductivity reduces conductive heat transfer between cells.
But room-temperature thermal conductivity alone provides an incomplete picture.
Battery engineers also need to understand how insulation performs when subjected to high temperatures, flame exposure and mechanical compression.
2. High-Temperature Resistance
During a severe thermal event, the barrier must retain useful thermal protection under temperatures far beyond normal battery operating conditions.
A material that performs well at room temperature but rapidly loses structural integrity during thermal runaway may provide limited protection.
3. Thin and Lightweight Construction
Battery packs have limited available space.
Adding insulation thickness can reduce volumetric efficiency and potentially affect battery energy density.
The engineering objective is therefore:
Maximum thermal protection with minimum thickness and mass.
This is one reason aerogel composites have attracted attention for EV battery applications.
4. Mechanical Performance Under Compression
Cell-to-cell insulation does not necessarily operate in an unloaded state.
Assembly tolerances, cell swelling and pack structures can place the material under compression.
Therefore, engineers should evaluate not only nominal thickness, but also:
Compression Ratio → Compressed Thickness → Thermal Performance After Compression → Recovery Behavior
These properties become increasingly relevant as battery architectures become more compact.
5. Electrical Insulation
A thermal barrier positioned around cells and electrical components may also need adequate dielectric properties.
This makes electrical insulation another important evaluation parameter alongside thermal and mechanical performance.
Why Aerogel Insulation Sheets Fit This Engineering Direction
Silica aerogel has an extremely porous nanoscale structure that restricts heat transfer, allowing high thermal resistance to be achieved with relatively limited material thickness.
When aerogel is combined with a reinforcing fiber substrate, the resulting composite can provide a balance between:
- Thermal insulation
- High-temperature protection
- Mechanical flexibility
- Lightweight construction
- Manufacturability
For EV applications, the material can therefore function as more than conventional insulation.
Its potential role is better described as a:
Cell-to-Cell Thermal Propagation Barrier
This distinction matters.
The purchasing conversation is moving away from comparing materials based purely on thermal conductivity and toward understanding how they behave within an actual battery safety architecture.
What Battery Engineers Should Test When Selecting an Aerogel Thermal Barrier
The implementation of GB 38031-2025 makes it increasingly important to evaluate insulation materials under conditions closer to actual battery operation and failure.
A useful technical evaluation should therefore consider several dimensions rather than relying on a single datasheet value.
| Evaluation | Why It Matters |
|---|---|
| Thermal Conductivity | Establishes baseline insulation performance |
| High-Temperature Exposure | Evaluates material stability during severe thermal events |
| Flame Exposure | Helps assess barrier integrity under direct thermal attack |
| Thermal Propagation Delay | Measures effectiveness in slowing heat transfer toward adjacent cells |
| Compression Ratio | Shows dimensional behavior under pack assembly pressure |
| Thermal Performance After Compression | Determines whether insulation remains effective in its installed state |
| Recovery / Rebound | Relevant to long-term mechanical interaction with cells |
| Electrical Insulation | Important where the barrier is integrated around electrical components |
| Smoke / Decomposition Behavior | Increasingly relevant to system-level safety |
| Cell-to-Cell Simulation | Provides application-specific validation beyond basic material testing |
The key point is simple:
A material certificate alone does not demonstrate thermal propagation performance inside a battery pack.
Application-oriented testing is becoming much more valuable.
SKYBOYS Aerogel Insulation Sheet for Battery Thermal Protection
SKYBOYS develops aerogel composite materials for thermal insulation and fire-protection applications, including insulation between battery cells and modules.
According to current technical specifications for SKYBOYS fiberglass aerogel materials, key parameters include:
- Thickness: 0.6–4.0 mm
- Customized dimensions available
- Long-term operating temperature: ≤600°C
- Maximum operating temperature: <1200°C
- Density: 200 ± 20 kg/m³
- Thermal conductivity at ambient temperature: ≤0.030 W/(m·K)
- Hydrophobicity: ≥95%
- Water contact angle: >110°
The material also provides relevant mechanical and electrical properties.
Compression Performance
- 1 MPa compression ratio: <30%
- 2 MPa compression ratio: <40%
Electrical Insulation Performance
- 1000 VDC / 60 s
- Insulation resistance: ≥500 MΩ
Voltage Resistance
- 3500 V AC / 60 s
- Leakage current: ≤3 mA
These properties are relevant because an EV battery thermal barrier needs to address several requirements simultaneously:
Thermal Insulation + High-Temperature Protection + Limited Installation Thickness + Mechanical Compression + Electrical Insulation
SKYBOYS also develops its aerogel materials for battery cells and modules where heat insulation, flame resistance, buffering and thermal runaway protection are required.
However, the increasingly stringent regulatory environment means that the next stage of material validation should go further than conventional material-property testing.
From Material Performance to Pack Safety
GB 38031-2025 does not mean that using aerogel automatically makes a battery pack compliant.
Compliance applies to the relevant battery system and prescribed test conditions.
That distinction is important for material suppliers.
Rather than claiming:
“Our material meets the new battery standard.”
A more technically appropriate approach is:
“Our material is designed to support battery thermal propagation mitigation strategies under increasingly stringent battery-system safety requirements.”
This also changes the development roadmap for aerogel insulation sheets.
Future validation should increasingly include:
- 600°C / 800°C / 1000°C / 1200°C thermal exposure
- Different material thicknesses
- Thermal propagation delay under different thicknesses
- Compressed-state thermal performance
- Compression ratio and recovery behavior
- Electrical insulation performance
- Cell-to-cell installation structures
- Simulated thermal runaway testing
- Thermal propagation testing under realistic battery conditions
The resulting data would allow engineers to answer a much more meaningful question:
Under defined installation conditions, how much can the barrier reduce or delay heat transfer from a failing cell to its neighbor?
That is far more useful to an EV battery engineer than simply knowing a room-temperature thermal conductivity value.
A New Sales Logic for Battery Insulation Materials
For suppliers of EV thermal protection materials, GB 38031-2025 also changes how products should be communicated.
The traditional message has often been:
Low Thermal Conductivity + Fire Resistance + Lightweight + Thin
Those properties remain important, but they describe the material rather than the customer’s engineering problem.
A stronger technical narrative is:
Thermal Runaway → Heat Propagation → Cell-to-Cell Barrier → Battery Pack Safety
This connects the material directly to what battery engineers are trying to accomplish.
Instead of selling an “aerogel insulation sheet,” suppliers are increasingly providing a:
Thermal propagation management component within the battery safety system.
That is a much more relevant position as battery packs move toward higher energy density, faster charging and stricter system-level safety requirements.
What This Means for EV Battery Manufacturers
For battery manufacturers, module developers and EV OEMs, material selection should increasingly move beyond comparing datasheets.
When evaluating a thermal barrier, several application-specific questions become important:
What is the cell chemistry?
What is the cell-to-cell spacing?
How much compression will the insulation material experience after assembly?
What thermal exposure should the barrier withstand?
How long does the neighboring cell need to remain below its critical temperature?
Does the material maintain electrical insulation after thermal and mechanical stress?
How does barrier thickness affect thermal propagation delay?
These questions connect material properties directly with pack-level engineering.
Conclusion: Battery Safety Is Moving From Warning to Prevention
The implementation of GB 38031-2025 on July 1, 2026 represents an important change in China’s EV battery safety framework.
The direction is clear:
Detecting thermal runaway is no longer enough. Preventing thermal propagation from escalating into pack-level fire or explosion is becoming the larger engineering objective.
For aerogel insulation materials, this creates both an opportunity and a higher technical threshold.
Future competition will increasingly depend not simply on who can provide the lowest thermal conductivity, but on who can demonstrate reliable performance under realistic combinations of:
High Temperature + Compression + Electrical Insulation + Cell-to-Cell Thermal Propagation
For battery manufacturers and engineers evaluating thermal barrier solutions, SKYBOYS can support the development and customization of Aerogel Insulation Sheets for cell-to-cell and module-level thermal protection applications.
Looking for an Aerogel Thermal Barrier for Your Battery Project?
Contact SKYBOYS to discuss:
- Cell dimensions
- Required material thickness
- Compression requirements
- Operating and peak temperatures
- Cell-to-cell spacing
- Thermal propagation protection targets
- Customized shapes and dimensions
SKYBOYS (Hangzhou) Technology Co., Ltd.
References
- GB 38031-2025 — Electric Vehicles Traction Battery Safety Requirements
National Standard Information Public Service Platform - China’s New EV Battery Safety Standard Implementation Overview
Hubei Provincial Department of Economy and Information Technology