Battery Pack Switch Structure for Voltage-Triggered Overcharge Blocking

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Solution Overview

Problem

Existing battery pack systems lack a reliable and reusable current blocking mechanism that can effectively prevent overcharging and subsequent overheating, especially in high-current applications like vehicle batteries.

Innovation Solution

A battery pack design incorporating a current blocking member made of electroactive polymer (EAP) with metal layers, capable of bending deformation when a potential difference exceeds a reference value, thereby disconnecting the switch and blocking current flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If thermal fuse, PTC thermistor, or TCO is used to block overcurrent, then the device can be reused, but the resistance increases as operation is repeated, increasing overall circuit resistance

Engineering Contradiction:

ImprovereusabilityVSAvoidcircuit resistance stability

Core Design Contradiction:

Duration of action of stationary objectVSReliability

Solution Approach 1:

The patent replaces the electrical resistance-based current blocking mechanism (PTC thermistor, TCO) with a mechanical system. The electroactive polymer membrane physically blocks the current path through bending deformation when voltage exceeds the reference value, rather than increasing electrical resistance. This mechanical blocking action does not suffer from resistance increase over repeated operations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Temperature

If PTC thermistor, TCO, or thermal fuse is used to block overcurrent, then the device can operate based on temperature, but it operates only after heat generation threatens safety, not immediately when overcurrent occurs

Engineering Contradiction:

Improvetemperature-based operationVSAvoidimmediate current blocking capability

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent implements preliminary action by setting the reference voltage value before overcurrent can generate dangerous heat. The electroactive polymer membrane is designed to bend and block the current path when the voltage reaches the reference value, preventing the condition that would lead to overheating rather than responding after heat is already generated.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the operating parameter from temperature-based (thermal fuse, TCO, PTC thermistor) to voltage-based operation. The electroactive polymer membrane responds to voltage changes directly, bending when the voltage between both surfaces reaches the reference value, enabling immediate current blocking based on electrical potential rather than thermal conditions.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If PTC thermistor, TCO, or thermal fuse is placed in high temperature environment of vehicle battery pack, then the device can be used, but it operates too early due to high c-rate and heat generation

Engineering Contradiction:

Improvehigh-temperature environment adaptabilityVSAvoidoperating timing accuracy

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent changes the operating parameter from temperature-based to voltage-based operation. The electroactive polymer membrane responds to voltage changes directly, bending when the voltage between both surfaces reaches the reference value, enabling immediate current blocking based on electrical potential rather than thermal conditions. This allows accurate operation timing even in high-temperature, high-c-rate environments.

Inventive Principle:

Principle #35Parameter changes

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 solution allows for immediate current blocking before temperature rises, enhancing safety by preventing overheating and potential explosions, while being reusable and suitable for high-current applications.

Implementation Method 1

the current blocking member may include an electro active polymer (EAP) layer; a first metal layer formed on one side of the EAP layer; and a second metal layer formed on the other side of the EAP layer

Methodology Applied

Scientific EffectElectroactive polymer: Electroactive Polymer

Data Source

PatentEP3800703B1Battery pack having structure capable of preventing overcharge, and vehicle comprising same

Publication Date: 2025.02.19 LG ENERGY SOLUTION LTD

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AI summary

A battery pack includes a battery module assembly including a first battery module and a second battery module; a first connector connected to a first electrode of the first battery module; a second connector connected to a second electrode of the second battery module and spaced apart from the first connector; a switch configured to connect the first connector and the second connector; a current blocking member connected to one side of the switch in a longitudinal direction and configured to turn off the switch by causing a bending deformation when a potential difference formed between both electrodes of the battery module is equal to or greater than a reference value.