Precision Die-Cut Separators: Key to Safe and Efficient Lithium Battery Packs

Whether it’s electric vehicle batteries or grid-level industrial and commercial battery storage, proper cell-to-cell protection is critical for mitigating damage in dangerous thermal runaway events, insulating cells from electrical arcing, and dampening vibration and mechanical stress. Die-cut battery cell separators, gaskets, and compression pads can be tailored for a range of applications, providing scalable solutions that can be seamlessly integrated into your battery system.

However, battery cell separators are not one-size-fits-all. Just as every battery pack is different, die-cut battery cell separators come in many shapes and sizes, made from a wide range of flexible materials like foams, papers, and ceramic materials. Navigating these material options can be daunting, which is why it’s important to work with a converting partner to understand the needs of your project and how to meet them with high-performance material converting solutions.

Today, we’ll be highlighting the important role battery separators play in battery safety and performance, as well as how to navigate the different types of separator materials. With safety and product performance on the line, battery cell separators should never be an afterthought.

Let’s take a closer look at why…

Battery Separators vs. Compression Pads vs. Gaskets

Before we jump in, it’s important to clarify the differences between battery cell separators, compression pads, and gaskets.

• Battery separators: A broad term including cell dividers, spacers, and compression pads both inside and outside the cell.
• Dividers and spacers: Provide thermal and electrical isolation by spacing cells to prevent heat transfer and arcing.
• Compression pads: Absorb vibration and accommodate expansion during charge/discharge cycles.
• Gaskets: Seal and protect components from environmental factors such as moisture, dust, and debris.

What Makes a Good Battery Cell Separator?

Battery packs are complex ecosystems. Amidst thermal, mechanical, and electrical stress, battery cells must function without fail. A well-designed separator should:

1. Ensure Thermal Management

Prevent hotspots, mitigate thermal runaway, and insulate against heat flow.

Ask: Does it insulate or conduct? Can it withstand thermal runaway?

2. Provide Electrical Insulation

Prevent arcing and shorts in high-voltage, densely packed modules.

Ask: Is it dielectric? Can it prevent shorting between cells?

3. Absorb Mechanical Stress

Cushion against vibration and mechanical shocks, especially in EVs.

Ask: Can it handle compression and return to shape?

4. Resist Moisture & Contamination

Survive harsh conditions without degrading or losing structure.

Ask: Is it stable in humidity, corrosion, or high heat?

5. Balance Cost vs. Performance

Match your budget without sacrificing safety or efficiency.

Ask: Does this material justify its cost in my application?

Selecting the Right Battery Spacer Material

Choosing the right spacer material involves balancing multiple criteria based on your design intent—thermal isolation, electrical insulation, impact resistance, or all three. Popular material options include:

• Foam (e.g., EVA, PORON, silicone) – excellent for compression and vibration absorption
• Nomex or aramid paper – great electrical insulators with high heat resistance
• Ceramic paper – used in high-temperature, fire-resistant battery applications
• Polyimide films (e.g., Kapton) – thin, flexible, and heat-resistant insulation

Each material offers unique benefits and trade-offs. Consult your material converter or partner early in the design stage to optimize for space, safety, and performance.