Cell-to-pack adhesives and the 2026 materials stack

Robotic application of cell-to-pack adhesives onto a battery cooling plate illustrates the processability demands that now define material selection in module-free EV battery architectures

(Image courtesy of Henkel)

The cell-to-pack battery adhesive has stopped being a consumable and now behaves as a structural element of the vehicle. Stripped of the module housing, the chemistry between cells must carry loads, conduct heat, isolate voltage and resist fire propagation in one layer. Henkel, Parker Lord and H.B. Fuller are publishing product lines that reflect how steep the requirement set has become.

What CTP demands of the material stack

Removing the module housing transfers responsibilities upward. Structural rigidity once supplied by steel or aluminium subframes must now come partly from the bond line. Thermal pathways shorten because cells sit closer to the cold plate, so any interface material has less depth in which to lose conductivity. Fire containment also migrates inward, since no module wall remains to stop a runaway event spreading laterally. Meanwhile, dispense lines must keep up with gigafactory cadence. Together, these constraints describe the envelope for any cell-to-pack battery adhesive shipping into series production.

Thermally conductive adhesives in cell-to-pack configurations must manage heat across every individual cell interface without the thermal buffering a conventional module housing would provide

(Image courtesy of Parker Lord)

Thermal management at the cell-to-pack battery adhesive interface

Parker Lord’s engineering materials place optimal lithium-ion cell performance between 20 and 35 degrees Celsius. The stated safe boundary runs from minus 40 to plus 80. Within CTP, the interface material does most of that work, since the thermal mass of a discrete module no longer buffers transients.

Henkel describes Loctite TLB 9300 APSi as the world’s first injectable thermally conductive adhesive for EV battery systems. Henkel characterises the product as a two-component polyurethane at 3 W/mK, with self-levelling, room-temperature cure and electrical insulation. Henkel states one of the world’s largest EV battery manufacturers has adopted it. On the 12th of May, the company added Loctite TLB 9270APS, which Henkel describes as a two-component polyurethane for cell-to-pack designs at 2 W/mK. Henkel cites a 40 to 45 minute working time and affinity for aluminium and PET film, which implies headroom on larger pack footprints before the chemistry kicks.

Parker Lord, meanwhile, identifies CoolTherm TC-2002 as the first commercial thermally conductive structural adhesive in the category. According to Parker Lord, it bonds nickel-plated steel to powder-coated aluminium, room-temperature curing with short fixture time. H.B. Fuller, separately, positions its EV Therm line as thermal management adhesives and dielectric coatings moving heat between cells and cooling systems. These three approaches sit at different points on the conductivity-versus-strength curve, yet all answer the same constraint, namely that the gap between cell and cold plate has closed.

H.B. Fuller’s EV Protect foam encapsulants self-level in liquid form to fill complex pack geometries, combining structural support, fire containment and NVH performance within a single material layer

(Images courtesy of H.B Fuller)

Structural integrity without the module housing

Parker Lord defines gap fillers as materials below 7 MPa lap shear, and adhesives as those above. In CTP that matters, because anything under the threshold is not load-bearing without a module case.

Parker Lord’s CoolTherm TC-850, launched in May 2025, is a room-temperature-curing thermally conductive structural adhesive. The company cites high elongation, redundant dielectric protection and high-speed application. Seth Carruthers, APS Division Market Manager, frames it as combining Parker’s competencies in thermal materials and structural bonding. The wider CoolTherm platform spans acrylic and urethane chemistries, covering cell-to-pack, cell-to-plate and cell-to-ribbon configurations across cylindrical, pouch and prismatic cells.

H.B. Fuller routes to the same load problem differently. EV Protect 5006 is positioned as a high-structural-performance encapsulant. It is designed, per H.B. Fuller, to reduce or replace conventional structural components, lowering part count and mass. Furthermore, the 5008 and 5009 variants step the stiffness up progressively, per Germaine Mariaselvaraj, Technical Service Manager at H.B. Fuller. EV Bond 300, the company states, compensates for thermal expansion and contraction as cells cycle. That implies a bond line designed to flex with the pack.

Thermal runaway containment

Parker Lord’s engineering materials confirm that arcing events and electrical shorts are initiating causes of thermal runaway. Consequently, dielectric coatings, gap fillers and seals sit on the critical path for pack safety, not only for performance.

H.B. Fuller describes EV Protect 4006 as a patented low-density two-component polyurethane foam encapsulant. The company cites a UL 94 V-0 fire rating and no hydrogen outgassing during cure. In liquid form, per H.B. Fuller, the material self-levels, fills complex pack geometries, then expands to encapsulate the cells. Its primary function, per H.B. Fuller, is preventing thermal propagation between cells during runaway, while keeping cells located and absorbing shock and vibration. That semi-structural role suggests fire containment and NVH performance can coexist in one chemistry.

Henkel, separately, describes its safety coatings as a reliable, scalable alternative to mica sheets. The company cites thermal stability up to 1,400 degrees Celsius and electrical protection designed for automated application. Substituting mica with a sprayable coating implies an integration shift, since mica is a discrete assembly step while a coating folds into the line.

Large-format cell-to-pack battery architectures place every structural, thermal and safety demand directly onto the adhesive layer, with no intermediate module housing to distribute load or contain heat

(Image courtesy of Henkel)

Processability for the cell-to-pack battery adhesive line

A material that cannot be dispensed at automotive cadence does not enter automotive production. Henkel’s Bergquist TGF 2030APS, launched on 12 May 2026, is characterised by Henkel as a silicone-free two-component thermal gap filler at 1.7 W/mK. The company also cites dispensability over 40 cc/sec, low compression force and room-temperature cure. Moreover, Henkel positions the silicone-free formulation as suited to sensitive battery applications and a reduced carbon footprint. Dr. Tobias Knecht, Global Market Strategy Head for E-Mobility at Henkel, positions the launch alongside TLB 9270APS as a response to fast-evolving architectures, including cell-to-pack and cell-to-chassis.

Parker Lord, similarly, describes CoolTherm TC-850 as enabling high-speed application and reducing the need for mechanical fastening. That implies it is pitched at the labour and cycle-time line items in a CTP build. Henkel’s published direction on pack housing covers robot-applied structural bonding for aluminium and multi-metal frames. Alongside it, serviceable foam gaskets allow packs to be reopened for repair, second-life or recycling. The robot-applied framing suggests bead consistency and repeatability carry as much weight as the bulk properties.

The systems integration problem

Read across the three suppliers, the trajectory is not toward a single best chemistry but toward a coordinated stack. Henkel states its debonding-on-demand technologies release bonds up to 12 MPa through thermal or electrical triggers, supporting repair, second-life and recycling. Alongside them sit Parker Lord’s reworkable urethane and acrylic options, and H.B. Fuller’s encapsulant variants tuned for different structural contributions. Henkel will further address the question at Battery Show Europe 2026, in a session led by Elizaveta Kessler titled “Technical requirements and design considerations for debonding in Cell-to-Pack EV battery systems”. Together, these directions suggest reversibility is now a design input rather than a downstream problem.

What the evidence points to is that no single property in the brief can be optimised in isolation without compromising another. Among them sit structural bonding, thermal conductivity, fire containment, dielectric isolation, processability and reversibility. The next phase of CTP materials work looks less like a race for higher numbers on any single axis, and more like making those axes coexist inside one bond line.

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