Thermo-mechanical Current Interrupter for Battery Safety

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Solution Overview

Problem

Existing safety current interrupter devices for secondary cells are either dependent solely on pressure or temperature for activation, lacking a combined response mechanism that can effectively handle both conditions, which limits their functionality and applicability, especially in high-power applications.

Innovation Solution

A safety current interrupter device incorporating a deformable material and membrane that deforms under both temperature and pressure changes, causing a conductive link member to rupture, thereby interrupting the current flow, with a design that allows for rapid activation within milliseconds and compatibility with a wide temperature range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a safety device is activated solely by pressure, then the current interrupter can be triggered by excessive internal pressure, but the device cannot be activated as a result of an increase in temperature

Engineering Contradiction:

Improvecurrent interrupter activationVSAvoidactivation conditions

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent combines pressure-actuated and temperature-actuated current interrupter devices into a single integrated safety system. The lid structure incorporates both a pressure-sensitive membrane mechanism and a temperature-sensitive deformable material mechanism, allowing the battery to respond to either pressure or temperature anomalies through a unified current interruption function.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The safety device is designed to perform multiple functions: it can be activated by pressure through the membrane mechanism, by temperature through the deformable material mechanism, and both mechanisms converge on the same current interrupter function. This multi-functional design enhances the versatility of the safety system.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If shape memory material is used for temperature-actuated safety venting, then the system can be activated by temperature rise, but the system cannot be activated by pressure increase and lacks current interrupter function

Engineering Contradiction:

Improvetemperature responseVSAvoidcurrent interrupter function

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent merges the temperature-actuated safety venting function with the pressure-actuated current interrupter function into a single integrated system. The deformable material responds to temperature changes while the membrane responds to pressure changes, and both mechanisms are connected to the same current interrupter circuit, ensuring comprehensive safety coverage.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The safety device incorporates multiple activation mechanisms (pressure and temperature) and multiple functions (safety venting and current interruption) within a single system. The deformable material provides temperature-responsive venting while the membrane provides pressure-responsive current interruption, and both mechanisms can work together or independently.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If separate pressure-actuated and temperature-actuated devices are used, then each can respond to its specific condition, but the device complexity increases and high-power applications are limited

Engineering Contradiction:

Improvecondition-specific responseVSAvoidnumber of devices

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent consolidates separate pressure-actuated and temperature-actuated devices into a single integrated current interrupter system. The lid structure houses both the pressure-sensitive membrane and temperature-sensitive deformable material, with both mechanisms converging on the same electrical circuit interruption function, thereby reducing overall system complexity while maintaining high-power capability.

Inventive Principle:

Principle #5Merging (Combining)

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 device provides enhanced safety by simultaneously responding to pressure and temperature anomalies, ensuring immediate and reliable current interruption, thus preventing explosions and maintaining performance across various applications, including high-power uses.

Implementation Method 1

a deformable material adapted to deform when a temperature reaches a threshold value; Excessive temperature causes a deformation of the deformable material which causes the rupture of the link member

Methodology Applied

Scientific EffectThermal deformation: Thermal Expansion

Implementation Method 2

a deformable membrane adapted to deform under the effect of excess pressure; Excessive pressure results in deformation of the membrane causing rupture of the link member

Methodology Applied

Scientific EffectPressure deformation: Deformation

Data Source

PatentUS8685555B2Thermo-mechanically activated current interrupter

Publication Date: 2014.04.01 SAFT GRP SA

AI summary

A safety current interrupter device for a rechargeable cell is provided comprising a deformable material (2) adapted to deform when the temperature reaches a threshold value, a deformable membrane (3) adapted to deform under the effect of pressure and/or deformation of the deformable material (2), and an electrically conductive link member (4), adapted to break as a result of the deformation of the deformable membrane (3).