Battery Module Temperature Detection Using Series PTC Thermistors

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Solution Overview

Problem

Existing battery modules require multiple ports on the protection IC chip for temperature sensing, which is inefficient and can miss heat generation in areas far from the temperature sensor.

Innovation Solution

A battery module that uses a single port of the protection IC chip by employing a high temperature detector with PTC thermistors connected in series, which contact each battery cell directly or through thermal films, to detect overall battery cell temperatures and block charging or discharging when a high temperature is detected.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a temperature sensor is provided in each battery cell to transmit temperature information to the protection IC chip, then the temperature of each battery cell can be monitored, but the protection IC chip requires many ports for temperature reception which increases device complexity

Engineering Contradiction:

Improvetemperature monitoring reliabilityVSAvoidprotection IC chip port quantity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Multiple temperature sensing functions are merged into a single detection port by connecting PTC thermistors from multiple battery cells in series. The protection IC chip only needs one port to read the combined resistance value that reflects the temperature status of all battery cells, thereby reducing the number of required ports while maintaining monitoring capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single detection port on the protection IC chip is designed to serve multiple functions: it can detect the temperature status of all battery cells simultaneously through the series-connected PTC thermistors, making the port universal for temperature monitoring across the entire battery module rather than requiring dedicated ports for each cell.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If a temperature sensor is provided in each battery cell, then temperature information can be transmitted to the protection IC chip, but only the battery cell temperature of the portion where the temperature sensor is located is measured which fails to detect heat generation in portions far from the temperature sensor

Engineering Contradiction:

Improvetemperature measurement coverageVSAvoidtemperature sensor quantity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

PTC thermistor materials are applied as thin films or coatings on the battery cell surfaces. These thin film PTC thermistors conform to the battery cell geometry and can detect temperature changes across the entire cell surface area, providing comprehensive temperature coverage without requiring multiple discrete sensors positioned at specific locations.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The solution uses composite material approaches by integrating PTC thermistor materials with the battery cell structure. The PTC thermistors are formed as integrated layers that cover the battery cell surfaces, creating a composite structure that provides both structural integrity and comprehensive temperature sensing capability across the entire cell.

Inventive Principle:

Principle #40Composite materials

3Reliability

If multiple temperature sensors are used to detect heat generation in all portions of battery cells, then comprehensive temperature monitoring is achieved, but the number of ports required on the protection IC chip increases

Engineering Contradiction:

Improveoverall temperature detection accuracyVSAvoidprotection IC chip port quantity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

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

This solution allows for efficient detection of high temperatures across all battery cells using only one port of the protection IC chip, effectively preventing overheating and ensuring battery stability.

Implementation Method 1

the high temperature detector includes a plurality of positive temperature coefficient (PTC) thermistors connected in series with each other

Methodology Applied

Scientific EffectPositive temperature coefficient (PTC) effect: Thermistor

Implementation Method 2

a thermal film, and a high temperature detector configured to detect whether a temperature of the battery module is above a predetermined temperature

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS12272798B2Battery module for detecting high temperature of battery cell

Publication Date: 2025.04.08 LG ENERGY SOLUTION LTD

AI summary

A battery module according to an embodiment of the present invention is composed of a plurality of battery cells. The battery module includes one positive (+) output terminal formed by connecting the plurality of battery cells, a field effect transistor (FET) provided on a current path between the positive (+) output terminal and an external device to block charging or discharging of a battery module, a protection integrated circuit (IC) chip for controlling the FET, and a high temperature detector for detecting whether the battery module is above a predetermined temperature and including a plurality of positive temperature coefficient (PTC) thermistors connected in series with each other.