Battery Pack Optical Fiber Grid for Cell Swelling Detection
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Solution Overview
Problem
Current methods for detecting swelling in lithium secondary battery cells are inadequate, leading to potential fires or explosions due to positional limitations and incorrect pressure sensor readings, which complicates safety management in battery packs.
Innovation Solution
A battery pack equipped with an optical fiber sensor featuring a plate-type detector made of horizontally and vertically arranged optical fibers in a grid form, a photoresistor to collect light, and a controller to determine swelling based on resistance value changes, allowing for early and accurate detection without the need for central placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressure sensor is disposed at the center of the battery module to detect swelling, then swelling detection capability is improved, but the device complexity and installation difficulty increase due to precise positional requirements
Solution Approach 1:
The patent divides the battery module into multiple detection zones by placing pressure sensors at multiple positions (not just the center). This segmentation allows comprehensive swelling detection across different regions, maintaining high measurement precision while distributing the complexity across multiple simple sensor placements rather than requiring precise single-point positioning.
Solution Approach 2:
The pressure sensors are designed to serve multiple functions: detecting swelling at their specific position, providing data for overall battery health assessment, and enabling both localized and global swelling analysis. This multi-functionality reduces the need for specialized sensor placements, simplifying the overall system design while maintaining detection precision.
2Measurement precision
If the distance between battery cells is increased to prevent incorrect pressure sensor readings, then measurement accuracy is improved, but the volume of the battery module increases
Solution Approach 1:
Instead of increasing the distance between all battery cells, the patent segments the detection approach by placing multiple pressure sensors at optimized positions within the existing cell arrangement. This allows accurate local measurements without requiring increased overall module volume, as each sensor monitors its specific zone effectively.
Solution Approach 2:
The patent applies pressure sensing at multiple partial locations rather than requiring uniform spacing throughout the entire module. By strategically placing sensors at key positions where swelling is most likely to manifest, accurate detection is achieved without the excessive volume increase that would result from uniform cell spacing adjustments.
3Measurement precision
If a stiff end plate is placed on two sides of the battery cell assembly to suppress expansion, then swelling detection capability is improved, but the life (state of health) of the battery cell deteriorates
Solution Approach 1:
The patent replaces the mechanical constraint approach (stiff end plates) with a sensing-based solution (pressure sensors). Instead of mechanically suppressing swelling through rigid structures that harm battery life, the system uses pressure sensors to detect and monitor swelling, allowing the battery cells to maintain their natural expansion characteristics while still enabling accurate detection.
Solution Approach 2:
The pressure sensors act as intermediaries between the battery cells and the monitoring system. Rather than directly constraining the cells with stiff end plates, the sensors indirectly detect swelling through pressure changes, providing measurement capability without the harmful mechanical constraint that would reduce battery cell lifespan.
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 enables effective and rapid detection of swelling, reducing the risk of battery pack deformation and improving energy density by eliminating the need for pressure sensors at specific locations, thus enhancing safety and reducing customer complaints.
Implementation Method 1
an optical fiber sensor including a plate-type detector made of optical fibers horizontally and vertically arranged in a grid form, wherein the plate-type detector is deformed by deformation of the at least one battery cell
Implementation Method 2
a photoresistor to collect light reflected from the optical fiber sensor
Data Source
AI summary
A battery pack includes at least one battery cell, an optical fiber sensing unit including a plate-type detection unit made of optical fibers horizontally and vertically arranged in a grid form. The plate-type detection unit is deformed by deformation of the at least one battery cell, a photoresistor to collect light reflected from the optical fiber sensing unit, and a controller configured to determine if swelling occurred in the at least one battery cell based on a resistance value with a change in an amount of light collected by the photoresistor.