Breakable Battery Separator for Thermal Runaway Mitigation
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Solution Overview
Problem
Rechargeable batteries, such as Lithium-ion batteries, are prone to thermal runaway and explosions due to mechanical impacts, which can cause electrical leaks, short-circuits, and heat release events, leading to serious safety hazards.
Innovation Solution
A breakable separator is introduced between the electrodes of a battery cell, designed to fracture under mechanical stress, creating a controlled electrical short and heat dissipation path to prevent thermal runaway. The separator has a specific fracture toughness and can include brittle features like notches or coatings to ensure safe discharge of energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional separator is used in the battery cell, then the battery maintains electrical insulation between electrodes during normal operation, but the battery becomes vulnerable to thermal runaway and explosions when subjected to mechanical impacts
Solution Approach 1:
The separator is designed to convert the harmful effect of mechanical impact into a beneficial safety mechanism. When the battery undergoes mechanical impact, the separator intentionally fractures to create electrical shorts, which triggers controlled energy dissipation and prevents uncontrolled thermal runaway. The harmful mechanical force is thus transformed into a protective action that saves the battery from catastrophic failure.
Solution Approach 2:
The separator acts as an intermediary component between the electrodes and the external environment. It normally maintains electrical insulation but under mechanical stress, it mediates the energy release by fracturing to create controlled shorts. This intermediary function allows the battery to safely dissipate energy through the separator's fracture rather than through uncontrolled thermal runaway.
2Adaptability or versatility
If the separator is made brittle with low fracture toughness to enable breaking under impact, then the separator can create controlled shorts to prevent thermal runaway, but the separator may be more susceptible to damage during normal battery operation and assembly
Solution Approach 1:
The separator is designed with non-uniform properties throughout its structure. Certain regions are made more brittle with lower fracture toughness to serve as preferred fracture sites, while other regions maintain higher strength to withstand normal operational stresses. This local differentiation allows the separator to selectively fracture in controlled locations under impact while remaining durable during normal use.
Solution Approach 2:
The separator is pre-conditioned during manufacturing to have specific brittle regions with controlled fracture characteristics. These pre-designed weak points are prepared in advance to ensure they will fracture at predictable locations and under specific impact conditions, rather than failing unpredictably during normal operation. The preliminary structuring of brittleness ensures reliable impact response without compromising operational integrity.
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 breakable separator effectively mitigates thermal hazards by allowing safe discharge of energy and heat dissipation, preventing thermal runaway, combustion, and explosions in battery cells subjected to mechanical impacts.
Implementation Method 1
The second portion of the separator is configured to break responsive to receipt of a force at the battery cell. The second portion of the separator may have a fracture toughness (KIc) between 0.2 to 5 MPa·m1/2 such that the second portion is configured to break during a high strain event.
Implementation Method 2
The break of the second portion may create a short in the power unit, such as a short between a first current collector associated with the first electrode and a second current collector associated with the second electrode, and allow the battery cell to discharge stored energy safely
Implementation Method 3
The first conductive member is configured to conduct and distribute heat during the electrical short to allow heat and electrical current to easily escape the power unit to ensure safe removal of generated heat preventing focused shorts and thermal runaway possibility.
Data Source
AI summary
The present disclosure includes systems, devices, and methods for operating a battery. The battery includes a power unit having a first electrode coupled to a first current collector and a second electrode. The first current collector is coupled to a first conductive member. The battery further includes a separator having a first portion interposed between the first electrode and the second electrode and a second portion positioned between the second electrode and the first conductive member. In some aspects, the second portion of the separator is configured to break responsive to receipt of a force to the battery to discharge the power unit safely without thermal runaway and catastrophic damage.