Fiber-Based Battery Module Casing for Pressure Venting

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Solution Overview

Problem

Lithium-ion battery modules are prone to bursting due to pressure buildup during fires or faulty modules, leading to the 'piston effect' where the cell contents are ejected, contaminating the environment with electrolyte and posing safety risks.

Innovation Solution

A fiber-based casing with a net-like structure is used to enclose the accumulator cell, allowing excess pressure to be safely released through gaps, preventing ejection and providing reliable protection against bursting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a rupture disc is installed to prevent outer casing bursting, then protection against bursting is improved, but the piston effect can still occur causing cell contents to be ejected

Engineering Contradiction:
Improveprotection against burstingVSAvoidpiston effect and ejection of cell contents
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a fiber-based casing as an intermediary component between the battery cell and the outer casing. This fiber casing acts as a mediator that catches and retains cell contents while allowing pressure to pass through, preventing the piston effect without compromising the pressure relief function of the rupture disc.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The fiber-based casing functions as a flexible protective layer that can deform under pressure but maintains its structural integrity to contain cell contents. The fibrous structure allows it to be flexible yet effective at preventing ejection of battery components.

Inventive Principle:
Principle #30Flexible shells and thin films

2Strength

If the outer casing is made robust to prevent bursting, then protection is improved, but the casing can soften in fire conditions allowing the piston effect to occur

Engineering Contradiction:
Improvecasing robustnessVSAvoidfire resistance
Core Design Contradiction:
StrengthVSTemperature

Solution Approach 1:

The patent employs a composite structure combining the outer casing with an inner fiber-based casing. This composite approach allows the outer casing to provide structural strength while the fiber-based inner casing provides temperature-resistant protection that maintains integrity under fire conditions without softening.

Inventive Principle:
Principle #40Composite materials

3Reliability

If a net-like fiber casing is used to prevent piston effect, then protection against ejection is improved, but pressure release must be ensured

Engineering Contradiction:
Improveprotection against ejectionVSAvoidpressure release
Core Design Contradiction:
ReliabilityVSStress or pressure

Solution Approach 1:

The fiber-based casing has a porous, net-like structure with intentional gaps between fibers. This porous structure allows pressure to pass through freely while the fibrous network maintains enough density to catch and retain cell contents, solving both the pressure release and ejection prevention requirements simultaneously.

Inventive Principle:
Principle #31Porous 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 fiber-based casing effectively contains the battery cell contents and safely vents excess pressure, preventing the 'piston effect and enhancing safety by maintaining the integrity of the battery module during adverse conditions.

Implementation Method 1

The casing comprises exclusively fibers such that continuous spaces remain between the fibers. Thus, according to the invention, the casing has a net-like structure or the like, in which spaces are present.

Methodology Applied
Scientific EffectPhysical containment through porous structure: Porosity

Implementation Method 2

The surrounding casing ensures that even if the outer casing of a battery cell bursts, the solid contents of the battery cell can be retained within the battery module

Methodology Applied
Scientific EffectMechanical support and retention: Mechanical Force

Data Source

PatentEP3031088B1Battery module having improved protection, and battery pack
Publication Date: 2021.03.31 ROBERT BOSCH GMBH
  • EP3031088B1 patent drawingFigure 1~3
  • EP3031088B1 patent drawingFigure 4~5

AI summary

The invention relates to a battery module, comprising at least one battery cell (2) and a shell (3) that surrounds the battery cell (2), wherein the shell (3) comprises fibers (4), and wherein intermediate spaces (5) remain between the fibers (4).