PORON® EVExtend® 4701-43RL Battery Pad Solutions for EV & HEV Pouch Cells

Lithium-ion technology is at the heart of modern electric and hybrid vehicles. Many traction batteries use pouch cells instead of cylindrical or prismatic cells, because pouch designs enable higher packing efficiency and energy density at lower manufacturing cost. However, pouch cells repeatedly swell and contract over their lifetime.

If the mechanical pressure on the cells is not kept within a narrow window, the result can be:

Sub-optimal electrochemical performance
Increased heat generation
Accelerated capacity fade and reduced battery life

This is where battery pads (pressure pads) made from advanced polyurethane foams become a critical design element.

Why Pouch-Cell Battery Pads Matter

Whether you design around a single pouch cell or a full stack of cells, the goal is the same: maintain a constant stack-up pressure on all cells during expansion and contraction cycles. Battery pads must:

Be soft and compressible enough to follow cell swelling
Avoid becoming too stiff at high compression or too soft at low compression
Provide stable, long-term elastic properties under heat and load

PORON® polyurethane battery pad materials are formulated to deliver exactly this behaviour thanks to their superior heat-aged compression set resistance (C-Set) – the ability to rebound after being compressed at elevated temperature.

PORON® Polyurethane Battery Pad Technology – Key Properties

According to the Rogers application note, PORON battery pad grades offer a combination of properties tailored to lithium-ion packs:

Compression Force Deflection (CFD)

Provides the initial pushback at beginning-of-life
Remains compressible enough to accommodate end-of-life swelling

Long-Term Reliability

Stable elastomeric behaviour and compression set over long-term heat aging
Support consistent electrochemical performance over the lifespan of the battery

Flammability & Thermal Insulation

Available grades with HBF and FMVSS 302 flammability performance
Insulating properties help reduce heat transfer between cells

Thickness Control

Tight thickness tolerances, typically ±10% or less, for predictable stack-up.

Vibration Management

Protects battery cells from shock and vibration during assembly and vehicle operation.

Energy Density Increase

Design tools and the broad product portfolio allow engineers to choose materials that achieve the required pressure while minimising uncompressed pad thickness at end-of-life – freeing space for more cells per module.

PORON® EVExtend® 4701-43RL – Optimised for EV & HEV Battery Packs

Within this portfolio, PORON EVExtend 4701-43RL is a polyurethane foam grade specifically developed as a battery pad material for EV and HEV pouch-cell modules. Its mechanical behaviour is tuned to help designers maintain the ideal pressure range on cells from beginning-of-life (BOL) through end-of-life (EOL). Flat CFD Curve – Controlled Pushback Over a Wide Compression Range

A central feature of EVExtend 4701-43RL is its flat Compression Force Deflection (CFD) curve:

Firmer at low compression – ensures the required initial pressure when cells are at nominal thickness.
Softer at high compression – limits force increase when pouch cells swell with ageing and cycling.

For pack designers this means:

More constant pushback force across the full working compression range
Reduced risk of over-pressurising ageing cells
Easier compliance with OEM pressure windows at both BOL and EOL

PORON® EVExtend® 4701-43RL Battery Pad Solutions for EV & HEV Pouch Cells

The CFD curves shown on the EVExtend sell sheet clearly illustrate how the EVExtend variants rise quickly at the start, then flatten compared to standard foams at higher strain levels.

Outstanding Compression Set & Long-Term Aging Performance

Battery pads must not “go flat” over years of service. EVExtend 4701-43RL is specified with a very low compression set of 5% at 70 °C (ASTM D3574), indicating excellent thickness recovery after compression at elevated temperature. Extended testing at 70% compression and 70 °C over durations up to 63 days shows that:

Extended testing at 70% compression and 70 °C over durations up to 63 days shows that

PORON EVExtend retains very low compression-set values, even after long exposures.
A referenced competitor material exhibits much higher compression set, meaning significant permanent thickness loss.

For your applications this translates into:

Stable thickness and pushback force over the lifetime of the pack
Consistent stack-up conditions despite thermal and mechanical cycling
Enhanced reliability of the electrochemical system

These results are consistent with the general statement in the application note that CFD and compression-set properties of PORON battery pads do not change significantly after long-term heat aging, helping maintain thickness and pushback forces over longer periods.

PORON® EVExtend® 4701-43RL Battery Pad Solutions for EV & HEV Pouch Cells - Compression Set

Additional Functional Benefits in EV & HEV Packs

Beyond compression control and ageing resistance, PORON EVExtend battery pads contribute to overall pack performance by:

Managing vibration and shock – cushioning cells during assembly and in-vehicle use
Supporting thermal management – acting as a thermal barrier between cells and components
Improving safety – with available grades meeting automotive flammability requirements (HBF, FMVSS 302) within the PORON battery pad family
Enabling higher energy density – optimised pressure/thickness behaviour helps minimise dead space, giving room for more cells per module

Typical Applications

PORON EVExtend 4701-43RL is suitable for a wide range of mobility and energy storage designs, including:

EV and HEV pouch-cell modules and packs
Battery pads and pressure management layers in prismatic-like stacks
Compressible insulation spacers between cells and module housings
Shock and vibration damping layers around sensitive cell areas
Tailored die-cut pads for cell separators, edge protection, and lid interfaces

EKO-TECH – Converting PORON EVExtend into Ready-to-Use Battery Pads

As a European converter of advanced technical materials, EKO-TECH transforms PORON EVExtend 4701-43RL into application-ready components that fit seamlessly into your manufacturing process. Our capabilities include:

Sheeting and Slitting
From rolls into custom sheets, strips and narrow widths
Adhesive Lamination
- Single or double-sided pressure-sensitive adhesive systems
- Self-adhesive battery pads for easy placement and rework on the line
Die-Cutting & Kiss-Cutting
- Complex 2D geometries matched to your module design
- Kiss-cut parts on liners for fast, ergonomic handling in assembly
Prototyping to Series Production
- Quick-turn prototypes for design validation
- Stable, scalable production for large EV/HEV programs

By combining Rogers’ PORON EVExtend technology with EKO-TECH’s converting expertise, you receive battery pad solutions that are precisely tuned to your compression targets, tolerances and assembly flow.

Engineering Support for Battery Designers

EKO-TECH supports OEMs and Tier suppliers throughout the development cycle:

Analysis of stack-up and target pressure windows
Support in material and thickness selection using PORON battery pad design guidelines
Samples, prototypes and test data for validation
Long-term supply concepts aligned with your ramp-up and lifetime volumes

PORON® and EVExtend® are trademarks of Rogers Corporation or one of its subsidiaries. EKO-TECH is an independent converter of PORON materials for industrial and automotive applications.

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Ready to Optimise Your EV or HEV Battery Pack?

If you are designing or upgrading pouch-cell battery modules and need stable, predictable compression over the full life of the pack, PORON EVExtend 4701-43RL is a proven solution. Maximise pouch-cell reliability and energy density with PORON® EVExtend® battery pads – talk to the EKO-TECH team today!