PTC Thermistor Battery Shell Temperature Sensing
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Solution Overview
Problem
Lithium secondary batteries are prone to deformation and potential explosion due to over-charge or high-temperature, leading to insulation film cleavage and short circuits, necessitating enhanced temperature detection sensitivity.
Innovation Solution
Incorporation of positive temperature coefficient (PTC) thermistors at strategic locations on the battery shell to accurately and instantly detect temperature variations, triggering a load switch to disconnect electrical power and prevent excessive deformation or explosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mechanical sensing technology or piezoelectric sensors are used to detect battery temperature, then the detection sensitivity can be improved, but the device complexity increases
Solution Approach 1:
The patent replaces mechanical sensing technology and piezoelectric sensors with PTC thermistors that utilize electrical resistance changes to detect temperature. This substitution eliminates complex mechanical components while achieving high-precision temperature detection through simple electrical measurements, thereby improving measurement precision while reducing device complexity
Solution Approach 2:
The patent utilizes the parameter change of electrical resistance in PTC thermistors with respect to temperature. By monitoring resistance variations, the system achieves sensitive temperature detection without requiring complex sensing mechanisms, thus improving measurement precision while maintaining simple device architecture
2Measurement precision
If PTC thermistors are placed at multiple locations on the battery shell, then the accuracy and sensitivity of temperature detection is improved, but the device complexity increases
Solution Approach 1:
The patent divides the battery shell into multiple locations and places PTC thermistors at each location to independently monitor temperature. This segmentation allows comprehensive temperature coverage and high detection accuracy while keeping each individual sensor simple, thus improving measurement precision without significantly increasing overall device complexity
Solution Approach 2:
The patent uses identical PTC thermistor sensors for multiple measurement locations, making each sensor type universal and multi-functional. This approach improves detection accuracy across different battery regions while avoiding the complexity of designing and implementing different types of sensors for different locations
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 provides precise and instant over-temperature protection, preventing battery deformation and explosion by effectively sensing temperature changes and cutting off power supply when thresholds are met, thereby enhancing safety.
Implementation Method 1
one or more positive temperature coefficient (PTC) thermistors serve as temperature sensing devices which are placed at appropriate locations to enhance accuracy and sensitivity of detection
Implementation Method 2
a thermally conductive paste may be introduced therebetween as an interface material
Data Source
AI summary
A secondary battery supplying electrical power to a load comprises a battery unit, at least one PTC temperature sensing device and a load switch. The battery unit is encompassed by a battery shell. The PTC temperature sensing device is disposed on a primary surface of the battery shell to effectively sense a temperature of the battery unit. The load switch connects to the battery unit and a load and determines whether the battery unit and the load switch are in electrical connection or in an open circuit state upon resistance variation of the PTC temperature sensing device. When the resistance of the PTC temperature sensing device increases by a threshold times within a specific temperature variation or time period, the load switch receives a control signal and accordingly switches to an open circuit state.