Internal Fuses for Battery Cell Thermal Runaway Mitigation
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Solution Overview
Problem
Lithium ion batteries face risks of thermal runaway, which can lead to explosions or fires due to increased energy capacity, and existing solutions do not adequately address the potential for cascading failures across adjacent cells.
Innovation Solution
Incorporating internal fuses within battery cells that electrically isolate areas upon reaching a predefined temperature threshold, typically between 135° C and 140° C, to mitigate thermal runaway by reducing current flow and compartmentalizing energy distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If batteries grow in capacity to meet increasing energy demands, then energy supply capability is improved, but the risk of thermal runaway and destructive failures increases
Solution Approach 1:
The battery cell is divided into multiple independent zones using separators and internal fuses. When thermal runaway occurs in one zone, the segmentation prevents it from propagating to other zones, thereby containing the harmful effects while maintaining high overall energy capacity
Solution Approach 2:
Heat-resistant coatings are applied as intermediary layers between battery components (anode, cathode, separator). These coatings act as thermal barriers that prevent direct heat transfer during thermal runaway events, reducing the severity of failures while allowing the battery to maintain high energy density
2Reliability
If internal fuses are added to electrically isolate areas during thermal runaway, then safety against cascading failures is improved, but device complexity increases
Solution Approach 1:
The internal fuses are integrated directly into the battery cell structure, merging the protection function with the existing cell components. This eliminates the need for separate external protection devices, reducing overall system complexity while maintaining high safety standards
Solution Approach 2:
The heat-resistant coatings serve multiple functions: they provide thermal protection during normal operation and act as fire barriers during thermal runaway events. This multi-functionality reduces the need for additional specialized components, simplifying the overall device structure
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 internal fuses effectively reduce the severity of thermal runaway events by isolating electrical areas, thereby minimizing the risk of explosions and fires, and slowing down the thermal runaway process, while also providing an additional layer of safety by reducing the total energy available during failures.
Implementation Method 1
In one embodiment, the fuse is a positive temperature coefficient (PTC) fuse. The fuse may conduct electricity at temperatures below the predefined threshold temperature and stop conducting electricity at temperatures at or above the predefined threshold temperature.
Implementation Method 2
In certain embodiments, the anode sheet and the cathode sheet are coated with heat resistant layers. The separator may similarly be coated with a heat resistant layer.
Data Source
AI summary
A battery is disclosed for reducing the severity of thermal runaway. The battery includes an anode sheet, a cathode sheet, and a separator situated between the anode sheet and the cathode sheet. The anode sheet, cathode sheet, and separator may be put together in a jelly roll configuration. The battery also includes internal fuses that subdivide the anode sheet, cathode sheet, or both, into electrically separate areas. The fuses are activated during thermal runaway and isolate separate areas of the sheet, thus reducing the total energy available during thermal runaway and reducing the severity. The fuses may be positive temperature coefficient (PTC) fuses that conduct current at normal operating temperatures but stop conducting current at temperatures above normal operating temperatures. The fuses may be placed in the current collectors, or directly into the anode sheet and cathode sheet themselves. In certain embodiments, the fuses may stop conducting when they reach a predefined threshold temperature or when an excessively large current passes through the fuses.