Battery Pack Venting Cap Structure for Thermal Runaway Mitigation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing battery packs with discharge valves for lithium ion batteries face safety issues due to high-temperature exhaust gas ejected from the discharge valve, which can induce thermal runaway and reduce safety.
Innovation Solution
A battery pack design featuring a heat-resistant cap with discharge gaps and a partition wall that guides high-temperature exhaust gas through controlled paths to reduce energy and prevent it from heating adjacent cells, using thermoplastic materials with enhanced heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a discharge valve is provided on the battery cell to release internal pressure, then safety against pressure increase is improved, but high-temperature exhaust gas is vigorously ejected which may induce thermal runaway and reduce safety
Solution Approach 1:
A heat-resistant cap is introduced as an intermediary component between the discharge valve and the external environment. This cap includes a discharge gap that forces the high-temperature exhaust gas to pass through a restricted path, allowing heat dissipation to the cap structure and preventing direct vigorous ejection of hot gas that could ignite adjacent cells.
Solution Approach 2:
The discharge gap in the heat-resistant cap transforms the direct linear ejection path into a controlled flow through a narrow gap, changing the dimensional characteristics of gas discharge. This restricts the gas flow to pass through the cap structure, converting kinetic energy into heat dissipation through the cap walls, thereby reducing the temperature of ejected gas.
2Strength
If the discharge valve opens at predetermined pressure to prevent rupture, then structural integrity is improved, but high-temperature gas is vigorously ejected causing adverse effects
Solution Approach 1:
The heat-resistant cap serves as a mediator that intercepts the vigorously ejected high-temperature gas from the discharge valve. The cap's discharge gap forces the gas to pass through a controlled path where heat is dissipated to the cap structure, converting the harmful vigorous ejection into a controlled, cooled flow that exits at lower temperature.
3Stress or pressure
If exhaust gas is discharged directly to the outside, then pressure relief is achieved, but thermal energy is not reduced allowing thermal runaway to occur
Solution Approach 1:
The heat-resistant cap acts as a thermal mediator that absorbs heat from the exhaust gas during the discharge process. The discharge gap forces the hot gas to contact the cap structure, transferring thermal energy to the cap material and reducing the temperature of the gas before it exits to the external environment.
Solution Approach 2:
The discharge gap transforms the direct pressure relief path into a thermally interactive flow path. By constraining the gas to pass through the narrow gap in the cap, the system adds a thermal dimension to the pressure relief function, allowing heat dissipation to occur during the pressure release process.
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 design effectively suppresses adverse effects from high-temperature exhaust gas, preventing thermal runaway and ensuring high safety by reducing the energy and flow direction of the ejected gas.
Implementation Method 1
The discharge valve is configured to open when an internal pressure exceeds a predetermined pressure
Implementation Method 2
The exhaust gas discharged to the valve-side end surface of the battery cell passes through a discharge gap including the first discharge gap and the second discharge gap, and is discharged from the exhaust opening to an outside
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A decrease in safety due to high-temperature exhaust gas ejected from an opened discharge valve is prevented. In a battery pack, a heat-resistant cap (8) is coupled to an end of a battery block including battery cells (1) each having a discharge valve on an end surface thereof and arranged in plural rows, and is accommodated in a battery case (2). A valve-side end surface (1a) of battery cell (1) is arranged at a first end of the battery block to which heat-resistant cap (8) is coupled. Heat-resistant cap (8) includes closing plate (31) providing a first discharge gap (15A) between the closing plate and end surface (10a) of the battery block, a peripheral wall (32) coupled to a periphery of closing plate (31) and providing a second discharge gap (15B) between the peripheral wall and an outer circumference of the battery block, a partition wall (33) disposed between end surfaces of adjacent battery cells and partitioning the first discharge gap (15A) into portions at end surfaces of battery cells (1). Exhaust gas discharged to the valve-side end surface (1a) passes through discharge gap (15) including first discharge gap (15A) and second discharge gap (15B), and is discharged from an exhaust opening to an outside.