Cell Frame and Header Cover for Battery Thermal Runaway Containment
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Solution Overview
Problem
Thermal runaway in battery packs is caused by uncontrollable decomposition reactions, which can propagate from one cell to adjacent cells, leading to uncontrolled heat generation and potential rupture, releasing hot gases and electrolytes.
Innovation Solution
A battery pack design featuring a cell frame with integrated weld straps, a fused connection, and a gas sensor, along with a protective coating and enclosure, to prevent the spread of thermal runaway by containing cell ejecta and disconnecting faulty cells, and a controller to monitor and shut down the system upon detecting gas venting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If battery cells are placed in close proximity to maximize energy density, then productivity and space utilization are improved, but thermal runaway can propagate from one cell to adjacent cells
Solution Approach 1:
The battery pack is divided into individual cell compartments within the cell frame, with each cell isolated from others. This segmentation prevents thermal runaway from propagating between cells while maintaining high energy density through optimized spacing and arrangement of cells within the compact housing.
Solution Approach 2:
The cell frame acts as an intermediary structure between adjacent battery cells, providing physical separation and containment. The frame includes features such as cell holders and spacing elements that maintain optimal distances between cells, preventing direct thermal contact while maximizing space utilization.
2Reliability
If weld straps are used to interconnect battery cells for electrical connection, then electrical conductivity is improved, but thermal runaway can spread through the conductive weld strap to other cells
Solution Approach 1:
The weld strap is extracted from direct contact with battery cell surfaces and repositioned to connect only to cell terminals or headers. This extraction removes the weld strap from the thermal pathway while maintaining its electrical connection function, preventing thermal runaway propagation through the conductive material.
Solution Approach 2:
Terminal headers or connection plates serve as intermediary components between weld straps and battery cells. The weld strap connects to these intermediaries rather than directly to cells, creating a thermal barrier while maintaining electrical conductivity through the intermediary connection points.
3Volume of stationary object
If battery cells are secured tightly within the housing to maximize space utilization, then volume efficiency is improved, but cell rupture can release hot gases and electrolytes into the environment
Solution Approach 1:
The cell frame incorporates controlled venting features that convert the harmful effect of cell rupture into a beneficial controlled release mechanism. When a cell fails, the frame provides designated vent paths that direct hot gases and electrolytes away from other cells and sensitive components, transforming an uncontrolled hazard into a managed safety feature.
Solution Approach 2:
The cell frame serves as an intermediary containment structure between battery cells and the external environment. It provides physical barriers and controlled venting pathways that intercept and manage cell rupture products, preventing direct release into the environment while maintaining tight integration of cells within the housing.
4Reliability
If monitoring systems are added to detect gas venting and shut down power transfer, then safety is improved, but device complexity increases
Solution Approach 1:
The battery pack monitoring system utilizes the cells' own venting behavior as the detection mechanism. Gas sensors detect venting directly from cell operation, and the control system automatically shuts down power transfer based on these readings, creating a self-monitoring system that leverages the cells' inherent safety signals without requiring complex external monitoring infrastructure.
Solution Approach 2:
The control system performs multiple functions: it manages normal power transfer operations, monitors gas sensor readings for safety conditions, and executes shutdown procedures. This multi-functionality consolidates safety monitoring and power management into a single integrated controller, reducing overall system complexity despite the added safety capabilities.
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 contains and prevents the propagation of thermal runaway, reducing the risk of cell damage and fire by isolating cells, disconnecting faulty connections, and actively monitoring and responding to gas production.
Implementation Method 1
a gas sensor disposed within the cavity, the gas sensor configured to detect the presence of gasses produced during decomposition of the battery cell
Implementation Method 2
a first fused connection between the weld strap and an at least one battery cell of the plurality of battery cells, wherein the fused connection is configured to disconnect the weld strap and the at least one battery cell upon reaching a temperature threshold
Implementation Method 3
Thermal runaway is caused by a decomposition reaction of the electrolytes within a battery cell reacting uncontrollably. The decomposition reactions are both exothermic and increase in rate as the temperature increases.
Implementation Method 4
A battery short circuit can rapidly heat due to Joule heating, causing a battery cell to reach a critical temperature wherein thermal runaway ensues.
Data Source
AI summary
A battery pack including a housing and a cell frame supported within the housing. The cell frame includes a plurality of openings to secure a plurality of battery cells, and a weld strap disposed within the cell frame configured to interconnect the plurality of battery cells. The battery pack also includes a cell header cover disposed adjacent to the battery cells and covering the weld strap. The cell header cover is configured to prevent battery cell particulate from circulating within the outer housing. The cell header cover and the cell frame cooperate to surround the battery cells.