Battery Pack Pressure-Driven Switch Safety Mechanism
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary battery packs, especially those with multi-cell structures, face significant safety risks due to potential fires or explosions from abnormal operations such as overcharge, overdischarge, and electrical shorts, which existing safety systems like BMS may not adequately address when they fail to receive power.
Innovation Solution
A battery pack design incorporating a pressure-driven switch that causes a short circuit upon detecting expansion in battery cells or modules, coupled with a cut-off portion at series connection regions to interrupt electrical connections, ensuring safety independently of the battery management system (BMS).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a battery management system (BMS) is used to protect battery cells from overcharge, overdischarge, and overcurrent, then the reliability of the battery pack is improved, but the system complexity increases and the BMS may fail when power is not supplied
Solution Approach 1:
The safety system is segmented into multiple independent protective mechanisms: pressure-driven switches at series connection regions, cut-off portions, and individual cell protection elements. Each segment operates autonomously to provide protection at different levels, reducing dependency on a single complex BMS system.
Solution Approach 2:
The battery pack incorporates self-protecting features through passive safety mechanisms that automatically activate without requiring external power or complex control logic. The pressure-driven switches and cut-off portions respond directly to physical conditions (pressure, temperature) and automatically interrupt circuits when thresholds are exceeded.
2Reliability
If passive safety mechanisms like pressure-driven switches and cut-off portions are added to protect against BMS failure, then the reliability is improved, but the device complexity increases
Solution Approach 1:
Multiple safety functions are merged into integrated components. The pressure-driven switch combines pressure sensing, switching action, and circuit interruption capabilities in a single element. The cut-off portion integrates thermal response, mechanical actuation, and electrical isolation functions, reducing the total number of discrete components needed.
Solution Approach 2:
The pressure-driven switches and cut-off portions are designed to handle multiple failure modes simultaneously. A single pressure-driven switch can respond to both overpressure from gas generation and thermal expansion from overheating, providing universal protection against various abnormal conditions without requiring separate specialized components.
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 design effectively prevents overcurrent and overvoltage transmission to external terminals, enhancing the safety and reliability of the battery pack by allowing the pressure-driven switch and cut-off portion to operate independently, even when the BMS is non-functional, thereby mitigating the risk of fires or explosions.
Implementation Method 1
at least one pressure driven switch configured to cause a short circuit in a portion or the entirety of the battery pack upon detecting expansion in volume of the battery cells or the battery modules
Implementation Method 2
a cut-off portion located at at least one series connection region between the battery cells or the battery modules to interrupt electrical connection in the battery pack when the short circuit occurs
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Disclosed herein is a battery pack including a power supply unit including two or more battery cells or battery modules electrically connected to each other, at least one pressure driven switch configured to cause a short circuit in a portion or the entirety of the battery pack upon detecting expansion in volume of the battery cells or the battery modules when the power supply unit malfunctions, a cut-off portion located at at least one series connection region between the battery cells or the battery modules to interrupt electrical connection in the battery pack when the short circuit occurs in the battery pack, and external input and output terminals connected to electrode terminals located at outermost sides of the power supply unit to supply power to an external device.