BESS Thermal Insulation - Best Thermal Insulation Products for BESS—Battery Energy Storage Systems

BESS Thermal Insulation - Buy high-performance BESS thermal insulation from Wedge. Compare WedGel EV aerogel pads, CAC350, FSMP microporous boards and fireproof enclosure panels for battery thermal-runaway protection.

Battery Energy Storage Systems require more than ordinary cabinet insulation. A complete BESS thermal-protection system may need thin cell separators, electrically insulating module barriers, rigid firewalls, cabinet linings and fire-resistant container partitions.

For this reason, the best BESS insulation solution is normally a combination of different materials, selected for each part of the battery system.

Wedge Industries Limited offers several branded insulation products suitable for BESS applications, ranging from ultra-thin WedGel EV aerogel thermal barriers to FSMP microporous boards, FP1000 fireproof boards, MagSil vermiculite panels and high-temperature installation accessories.

Which Wedge Products Are Most Suitable for BESS?

The most suitable products from the Wedge Insulation catalogue are:

Priority	Wedge product	Recommended BESS application
1	WedGel EV 650EV	Ultra-thin cell-to-cell thermal barriers
2	WedGel EV FSMP 1000EV	Rigid module-to-module fire barriers
3	WedGel EV OXF	Flexible insulation around complex battery geometries
4	WedGel EV AlSi 250EV	Flexible, very-high-temperature protection
5	WedGel CAC350	Strong aerogel composite barriers and heat shields
6	FSMP microporous boards and panels	Rack, module, cabinet and top-cover thermal barriers
7	FP1000 and SP1150 fireproof boards	BESS cabinet and container fire partitions
8	MagSil fire-resistant vermiculite boards	Container walls, fire-rated enclosures and equipment-room partitions
9	WedgeMW mineral wool	General container-wall thermal and acoustic insulation
10	WSC600 high-silica cloth and HTAL1000 adhesive	Protective facings, wraps and installation accessories

The WedGel EV product family should be the first product range offered to battery manufacturers and BESS integrators, because it is specifically designed for battery cell, module and pack thermal barriers.

BESS Thermal Insulation - Why BESS Requires Special Thermal Insulation

BESS Thermal Insulation - Lithium-ion cells can generate heat during normal charging and discharging. Abnormal conditions such as internal short circuits, mechanical damage, overcharging or manufacturing defects can create much higher temperatures.

When one cell enters thermal runaway, heat may transfer to neighbouring cells and modules. This can lead to progressive thermal-runaway propagation.

A properly engineered passive insulation system can help:

• Reduce heat transfer between adjacent cells

• Delay cell-to-cell and module-to-module propagation

• Electrically isolate battery components

• Protect busbars and the battery-management system

• Reduce heat exposure to the battery enclosure

• Support fire compartmentation inside the BESS container

• Provide additional response time for detection, ventilation and suppression systems

No single insulation material performs all these functions. The insulation should be selected according to its position in the system.

WedGel EV Aerogel Insulation for BESS Batteries

Best overall range for cell, module and battery-pack protection

WedGel EV is Wedge’s most directly applicable product family for BESS thermal-runaway protection.

The range consists of four grades:

• WedGel 650EV

• WedGel AlSi 250EV

• WedGel FSMP 1000EV

• WedGel OXF

These products are lightweight, thin, thermally insulating, electrically insulating and flame retardant. Available thicknesses range from approximately 0.24 mm to 10 mm, depending on the grade. The catalogue lists thermal conductivity at 25°C from 0.018 to 0.040 W/m·K, UL94 flame-retardant performance and EN 13501-1 Class A1 fire reaction across the four grades.

WedGel 650EV—Best for Minimum Thickness

Recommended for:

• Cell-to-cell separators

• Prismatic cell sidewalls

• Module-to-module barriers

• Top-of-module heat shields

• BMS and busbar thermal isolation

WedGel 650EV provides the lowest reported thermal conductivity in the battery-specific range:

• Thermal conductivity: 0.018 W/m·K at 25°C

• Service temperature: −50°C to +700°C

• Short-term temperature resistance: 1,400°C

• Available thickness: 0.24–10 mm

• Breakdown voltage: ≥10 kV/mm

• Compression strength: 85 kPa at 10% compression

This is the preferred Wedge grade where the customer needs the highest insulation performance in the smallest possible gap.

WedGel FSMP 1000EV—Best Rigid Module Barrier

Recommended for:

• Module-to-module insulation

• Rigid battery firewalls

• Top-of-rack heat barriers

• Structural battery-pack barriers

• High-temperature gap fillers

Key catalogue properties include:

• Thermal conductivity: 0.021 W/m·K at 25°C

• Service temperature: +6°C to +1,000°C

• Short-term temperature resistance: ≥1,400°C

• Thickness: 2–10 mm

• Compression strength: 330 kPa

• Breakdown voltage: ≥10 kV/mm

FSMP 1000EV is the preferred grade where a BESS designer requires a more rigid and compression-resistant thermal barrier rather than a soft blanket.

WedGel OXF—Best for Flexible and Complex Shapes

Recommended for:

• Cylindrical cell arrangements

• Irregular module gaps

• Curved surfaces

• Battery-pack corners

• BMS, connector and busbar isolation

WedGel OXF offers very high flexibility, thicknesses from 0.3 mm to 10 mm, thermal conductivity of 0.023 W/m·K at 25°C and breakdown voltage of at least 10 kV/mm. Its flexibility makes it easier to fit around complex battery geometries.

WedGel AlSi 250EV—Best for Maximum Temperature Resistance

Recommended for:

• High-temperature module barriers

• Areas exposed to direct flame or hot ejecta

• Flexible top shields

• High-temperature battery compartment protection

WedGel AlSi 250EV provides:

• Service temperature up to 1,300°C

• Short-term temperature resistance of at least 1,500°C

• Thickness from 0.8 mm to 10 mm

• High flexibility

• Breakdown voltage between 2 and 8 kV/mm

Its thermal conductivity is higher than 650EV, but it offers the highest temperature capability in the WedGel EV range. It is therefore suitable where temperature resistance is more important than achieving the lowest possible thermal conductivity.

WedGel CAC350 Carbon Aerogel Composite

Best for strong, flexible and electrically insulating battery barriers

WedGel CAC350 is a carbon-fibre-reinforced silica aerogel composite supplied in rolls or sheets.

It combines:

• Thermal conductivity of 0.021 W/m·K at 25°C

• Continuous service temperature of 350°C

• Short-term resistance to 1,200°C

• Thickness from 1 mm to 25 mm

• Compression strength of 1.75 MPa

• UL94 V-0 flame-retardant classification

• Insulation resistance of at least 500 MΩ at 2,500 V DC

• Flashover withstand of 3,820 V DC without breakdown

The catalogue specifically identifies CAC350 for EV battery cell-to-cell and module-to-module fire barriers.

When should CAC350 be selected?

CAC350 is particularly attractive when the customer requires:

• Better mechanical strength than a conventional soft aerogel blanket

• A black finished thermal barrier

• Flexible roll or sheet supply

• High electrical resistance

• Die-cut module separators

• Combined thermal, vibration and fire-barrier performance

For large stationary battery modules, CAC350 can be proposed as an alternative to standard aerogel pads where durability and compression strength are important.

FSMP Microporous Insulation for BESS Modules and Cabinets

Best rigid insulation where space is limited

Wedge’s FSMP microporous insulation family includes boards, blankets, slated panels, ceramic-cloth-covered panels, hydrophobic boards and Slim MicroSilica boards.

The product family has reported conductivity between 0.021 and 0.062 W/m·K, temperature classifications from 800°C to 1,260°C and Class A1 non-combustible performance.

Recommended FSMP products for BESS

FSMP 1000S HD and FSMP 1200 HD

These high-strength microporous boards are suitable candidates for:

• Rigid module firewalls

• Battery-rack side and top barriers

• Cabinet-to-cabinet thermal separation

• Barriers below or above battery modules

• Structural insulation behind fireproof boards

The high-strength FSMP range provides thermal conductivity as low as 0.022–0.024 W/m·K at 200–400°C, Class A1 non-combustible performance and compressive strength up to 0.78 MPa.

FSMP-HEC Microporous Ceramic-Cloth Panels

FSMP-HEC panels have a fumed-silica microporous core covered with high-temperature glass cloth.

Available grades include:

• HEC 1260

• HEC 1100S

• HEC 1100T

• HEC 800

• HEC 1200HD

The cloth covering improves handling, protects the core and helps reduce dust during fabrication and installation. These panels can be considered for cabinet barriers, cable-area protection and removable thermal shields.

MS Slim MicroSilica Boards

Wedge MS grades include:

• MS 1200

• MS 1000S

• MS 1000T

• MS 900

• MS 1200HD

These are thin, rigid, Class A1 non-combustible microporous boards with temperature classifications from 900°C to 1,200°C. They are suitable where BESS cabinet or rack designers need a rigid barrier with very low heat transfer but cannot accommodate a thick conventional insulation board.

FP1000 and SP1150 Fireproof Boards

Best for BESS cabinet and container fire partitions

Wedge FP1000 and SP1150 are high-density calcium-silicate-based fireproof boards for structural fire protection.

The catalogue reports:

Property	FP1000	SP1150
Fire rating at 10 mm	240 minutes	120 minutes
Short-term temperature	1,200°C	1,000°C
Thermal conductivity at 20°C	0.16 W/m·K	0.18 W/m·K
Density	880–900 kg/m³	1,150 kg/m³
Thickness availability	4–30 mm	4–30 mm
Fire classification	A1	A1

These boards are large, mechanically strong and suitable for fire doors, steel duct cladding, smoke barriers and industrial apparatus construction.

Recommended BESS applications

• Internal BESS container partitions

• Battery-room firewalls

• Separation between battery and power-conversion compartments

• Fire-resistant cabinet walls

• Cable and electrical-room partitions

• Enclosure doors and access panels

• External protection around battery racks

Important: A material-level fire rating does not automatically give the complete BESS enclosure the same rating. The complete wall, joint, frame, door and penetration assembly must be tested or assessed for the project.

CalSil HDSP450 Self-Supporting Panels

Best for mechanically strong equipment enclosures

CalSil HDSP450 is a calcium-silicate-based, self-supporting mineral panel with:

• Continuous temperature classification of 450°C

• Thermal conductivity of 0.16 W/m·K

• Compressive strength of 9.3 N/mm²

• Standard panel size of 2,440 × 1,220 mm

• Thicknesses from 6 mm to 25 mm

The catalogue recommends HDSP450 for apparatus enclosures, fire-protection walls, partitions and heat-shield barriers. It can therefore be considered for BESS equipment cabinets and internal equipment-room partitions where mechanical strength is more important than ultra-low thermal conductivity.

MagSil Fire-Resistant Vermiculite Boards

Best for economical container firewalls

Wedge MagSil boards are compression-moulded from expanded vermiculite and a special binder. They are lightweight, chemically stable and available in customised sizes and thicknesses.

The catalogue lists:

• Temperature resistance up to 1,200°C

• Fire ratings from 60 to 240 minutes, depending on thickness

• Fire-barrier protection against flame and heat spread

• Asbestos-free and organic-free construction

• Corrosion resistance

MagSil can be considered for BESS container walls, fire-rated partitions, equipment-room linings and heat shields where a thicker, economical structural fire barrier is acceptable.

WedgeMW Mineral Wool for BESS Container Walls

Suitable for general enclosure insulation—not direct cell barriers

WedgeMW mineral wool is available in densities from MW40 to MW200.

Its reported properties include:

• Thermal conductivity of 0.036 W/m·K at 25°C

• Working temperature of 650°C

• Maximum use temperature of 750°C

• Class A1 non-combustible classification

• Moisture absorption below 1%

• Thermal and acoustic insulation

WedgeMW can be installed between double-skin BESS container walls to provide general thermal insulation, sound absorption and passive fire protection.

However, it is not the preferred product for cell-to-cell barriers because it requires more thickness than aerogel and does not provide the same thin, precision-cut battery-interface format.

WSC600 High-Silica Cloth

Protective facing for BESS insulation assemblies

WSC600 E-Glass/High-Silica Cloth contains 96% amorphous silica and is available in thicknesses from 0.25 mm to 1.3 mm.

It provides:

• Continuous service to 982°C

• High dielectric strength

• High corrosion resistance

• Flame resistance

• Plain and self-adhesive options

WSC600 can be used as a protective facing, wrap or encapsulation material around aerogel, microporous or ceramic insulation components. It improves handling and protects softer insulation layers against abrasion.

It should normally be used as part of a composite barrier rather than as the main thermal insulation layer.

HTAL1000 High-Temperature Adhesive

Wedge HTAL1000 WK84 and WK84/16 are inorganic, asbestos-free and incombustible adhesives for bonding:

• Microporous insulation

• Calcium silicate boards

• Ceramic fibre

• Fireproof boards

• Insulation to steel substrates

The paste and fluid variants provide continuous temperature resistance up to 1,000°C.

HTAL1000 can be offered as an installation accessory for BESS firewalls and cabinet linings. For direct use close to battery cells, the complete bonded assembly should first be evaluated for dielectric performance, vibration, outgassing and compatibility with the battery design.

Recommended Wedge Insulation System by BESS Location

BESS location	First recommendation	Alternative or supporting product
Between individual cells	WedGel 650EV	WedGel OXF
Between prismatic cells	WedGel 650EV	WedGel CAC350
Around cylindrical cells	WedGel OXF	WedGel AlSi 250EV
Between battery modules	WedGel FSMP 1000EV	CAC350 or FSMP-HEC
Above battery modules	WedGel 650EV or FSMP 1000EV	FSMP HD board
Around BMS and busbars	WedGel 650EV or OXF	High-silica cloth facing
Battery-rack sidewalls	FSMP 1000S HD	MS Slim MicroSilica
Cabinet lining	FSMP-HEC	FP1000
Cabinet-to-cabinet barrier	FP1000	MagSil
Container internal partition	FP1000 or SP1150	MagSil or HDSP450
Double-skin container wall	WedgeMW	FP1000 facing
Cable and penetration protection	FSMP-HEC	WSC600 and ceramic tape
Board installation on steel	HTAL1000	Mechanical fastening as engineered

Best Recommended Hybrid BESS Insulation Systems

Premium ultra-thin battery module system

• Cell-to-cell: WedGel 650EV

• Module-to-module: WedGel FSMP 1000EV

• Top heat shield: WedGel CAC350

• Protective facing: WSC600

• Cabinet barrier: FSMP 1000S HD

This system is suitable where minimum thickness, low weight and high energy density are priorities.

High-temperature BESS safety system

• Cell and module barriers: WedGel AlSi 250EV

• Rigid module firewall: FSMP 1200 HD

• Cabinet lining: FP1000

• Container partition: MagSil fire-resistant board

• High-temperature fixing: HTAL1000

This configuration is suited to projects that prioritise high-temperature protection and passive fire compartmentation.

Economical containerised BESS system

• Module barriers: WedGel 650EV or CAC350

• Rack barriers: MS 1000S MicroSilica

• Container wall insulation: WedgeMW

• Internal fire partitions: FP1000 or MagSil

• Protective fabric and joint treatment: WSC600 and suitable Wedge high-temperature accessories

Products Not Recommended as Primary Thermal-Runaway Barriers

Some Wedge products are excellent for building and cold-storage insulation but should not be positioned as the primary barrier directly between lithium-ion cells.

These include:

• PIR boards

• PU foam boards

• XPS foam boards

• Conventional vacuum insulation panels

• PET acoustic panels

• Building-grade insulation coatings

They may be suitable for HVAC, condensation control or external temperature management, but direct cell and module thermal-runaway zones should primarily use the WedGel EV, CAC350, FSMP microporous or suitably engineered inorganic fire-barrier products.

Custom BESS Insulation Components from Wedge

Wedge can supply BESS thermal insulation in customised formats, subject to product grade and project requirements:

• Die-cut aerogel pads

• Cell separator sheets

• Module barrier panels

• Self-adhesive thermal pads

• Custom-width rolls

• Rigid microporous boards

• Ceramic-cloth-covered panels

• Cabinet lining boards

• Fireproof container partitions

• High-silica fabric facings

• Composite aerogel and fire-board systems

The WedGel EV catalogue also includes self-adhesive options and identifies uses including cell wraps, module barriers, top-of-pack heat shields, gap fillers and thermal isolation around BMS and busbars.

Information Required for a BESS Insulation Quotation

To receive a technical recommendation and commercial quotation, send Wedge the following information:

• Battery chemistry and cell type

• Cell or module dimensions

• Available insulation gap

• Required insulation thickness

• Normal operating temperature

• Expected abnormal or thermal-runaway temperature

• Required electrical breakdown voltage

• Compression or expansion requirement

• Flexible or rigid material preference

• Required fire or system test

• Adhesive-backed or plain construction

• Drawing, CAD file or sample

• Prototype and annual quantity

• Installation location and environmental conditions

Based on these details, Wedge can recommend the appropriate WedGel, CAC350, FSMP, calcium silicate or vermiculite product and prepare samples for technical evaluation.

Why Buy BESS Thermal Insulation from Wedge?

Wedge Industries Limited offers a broad range of high-performance insulation materials covering six product families and service temperatures from approximately −200°C to +1,800°C. The portfolio includes thin, lightweight insulation, non-combustible fire barriers, rigid structural boards and high-temperature fabrics and adhesives.

Customers can source multiple layers of the BESS thermal-protection system from a single supplier:

• Aerogel cell and module pads

• Microporous battery barriers

• Fireproof cabinet boards

• Container partition materials

• Mineral wool enclosure insulation

• High-temperature cloth and adhesives

• Custom-cut and fabricated components

Request a Technical Proposal and Price

Send your BESS module drawing, required thickness, operating conditions and quantity to the Wedge technical team.

Email: info@wedge-india.comTelephone: +91 97175 06848

Request:

• Product datasheets

• Sample thermal barriers

• Prototype die-cut pads

• Material comparison

• Project-specific insulation recommendations

• Bulk commercial quotation

The best Wedge product for BESS depends on where the insulation will be installed.

For direct cell-to-cell and module-to-module thermal-runaway barriers, the strongest commercial recommendation is the WedGel EV range, particularly 650EV, FSMP 1000EV, OXF and AlSi 250EV.

For a stronger aerogel composite, WedGel CAC350 is an excellent option. For rigid, ultra-thin rack and cabinet barriers, FSMP microporous boards are the preferred choice. For BESS container walls and fire partitions, FP1000, SP1150, HDSP450 and MagSil provide structural fire-protection options.

The safest approach is a layered system combining:

WedGel EV aerogel pads + FSMP microporous barriers + FP1000 or MagSil fireproof enclosure boards.

This combination provides thin thermal insulation close to the cells and stronger passive fire protection around the battery rack, cabinet and container.

Frequently Asked Questions

Which Wedge insulation is best for BESS cells?

WedGel 650EV is the preferred starting point for thin cell-to-cell insulation because it has thermal conductivity of 0.018 W/m·K at 25°C, thickness options starting at 0.24 mm and breakdown voltage of at least 10 kV/mm.

Which Wedge product is best between battery modules?

WedGel FSMP 1000EV is recommended where a rigid, compression-resistant module barrier is required. CAC350 is suitable where greater flexibility and mechanical durability are needed.

Which material is best for a BESS cabinet firewall?

FSMP high-strength microporous boards are suitable where low thickness and high thermal performance are required. FP1000 is more suitable where a structural fireproof board and longer fire separation are required.

Can mineral wool be used in BESS containers?

Yes. WedgeMW can be used inside double-skin container walls for general thermal, fire and acoustic insulation. It is not normally the first choice directly between battery cells.

Can Wedge supply adhesive-backed battery insulation pads?

The WedGel EV range includes self-adhesive options. Final adhesive selection should be based on the battery surface, temperature, compression, dielectric and ageing requirements.

Does a UL94 V-0 insulation pad certify the complete BESS?

No. UL94 V-0 is a material flammability classification. The complete battery module, rack, cabinet and container must be validated under the system-level requirements applicable to the project.

Does Wedge provide custom BESS insulation samples?

Wedge can prepare project-specific samples, die-cut pads, sheets and panels based on battery dimensions, available gap, temperature exposure, voltage requirements and required quantities.