Battery Cell Stack Resin Layer for Bonding and Flame Retardancy

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Solution Overview

Problem

Existing battery cell stacks face challenges in manufacturing complexity, increased costs, weight and volume due to fastening parts and cooling equipment, and fire extinguishment difficulties, while conventional adhesive methods generate waste and require complex processes.

Innovation Solution

A solvent-free adhesive resin layer with integrated phosphorus-based and nitrogen-based flame retardants is applied to battery cells, simplifying manufacturing and enhancing operational stability and flame retardancy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If fastening parts and cooling equipment are added to increase battery capacity and output, then the battery module's power and energy density improve, but the volume and weight increase, leading to decreased output proportion

Engineering Contradiction:
Improvebattery outputVSAvoidbattery module weight
Core Design Contradiction:
PowerVSWeight of stationary object

Solution Approach 1:

The patent combines the fastening function and flame retardancy function into a single resin layer that bonds battery cells together while providing fire safety. This merging eliminates the need for separate fastening parts and cooling equipment, reducing overall weight and volume while maintaining structural integrity and safety.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The resin layer serves multiple functions simultaneously: it acts as an adhesive to bond battery cells, provides flame retardancy through phosphorus-based and nitrogen-based flame retardants, and offers structural support. This multi-functionality replaces multiple separate components with a single universal material system.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Strength

If tape type adhesive is used to manufacture battery cell stack, then the cells can be bonded together, but the manufacturing processes and equipment become complicated and large quantities of waste such as release paper are generated

Engineering Contradiction:
Improvebonding strengthVSAvoidmanufacturing complexity
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The patent extracts and eliminates the release paper component from the adhesive system by using a solvent-free adhesive formulation that does not require a release layer. This simplifies the manufacturing process by removing the steps of applying release paper and subsequently removing it, reducing both process complexity and waste generation.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the physical and chemical parameters of the adhesive system by using a solvent-free formulation with specific viscosity ranges (2,000-18,500 cps at 160°C) and incorporating flame retardants at specific concentrations (10-50 parts by weight). These parameter changes enable the adhesive to function without release paper while maintaining bonding strength and adding fire safety.

Inventive Principle:
Principle #35Parameter changes

3Quantity of substance

If battery module is composed of high capacity and high output battery cells, then the energy density improves, but fire safety becomes more difficult to manage when fire occurs

Engineering Contradiction:
Improveenergy capacityVSAvoidfire hazard
Core Design Contradiction:
Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent creates a composite material system by combining the resin adhesive with phosphorus-based flame retardants (such as phosphate compounds, phosphonate compounds, phosphinate compounds, phosphine oxide compounds, phosphazene compounds, and metal salts) and nitrogen-based flame retardants (such as melamine and melamine derivatives). This composite structure maintains the adhesive's bonding function while integrating fire safety capabilities, allowing high-capacity battery cells to be safely contained.

Inventive Principle:
Principle #40Composite materials

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solvent-free adhesive resin layer improves adhesion, impact resistance, and flame retardancy, reducing manufacturing complexity and increasing productivity while maintaining stability and safety.

Implementation Method 1

a resin layer which is wholly or partially in contact with an outer surface of at least one of the plurality of battery cells, wherein the resin layer includes a solvent-free adhesive

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 2

the resin layer includes at least one of a phosphorus-based flame retardant and a nitrogen-based flame retardant, such that operational stability and flame retardancy are simultaneously improved

Methodology Applied
Scientific EffectFlame retardancy:

Data Source

PatentEP4178012B1Battery cell stack and manufacturing method thereof
Publication Date: 2026.04.29 SK ON CO LTD
  • EP4178012B1 patent drawingFigure 1~2
  • EP4178012B1 patent drawingFigure 3

AI summary

A battery cell stack of the present invention includes a plurality of battery cells and a resin layer wholly or partially in contact with an outer surface of at least one of the plurality of battery cells, wherein the resin layer includes a solvent-free adhesive and a flame retardant, and has a peel strength of 1,000 gf/in to 3,000 gf/in measured according to ASTM D3330, and a shear strength of 20 kgf/sq-in to 100 kgf/sq-in measured according to ASTM D1002, and the flame retardant includes one or more of a phosphorus-based flame retardant and a nitrogen-based flame retardant, such that the operational stability and flame retardancy may be simultaneously improved, while simplifying materials and processes necessary to manufacture the battery cell stack.