Interruptible Thermal Interface for Battery Runaway Isolation
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Solution Overview
Problem
Next-generation electric vehicle batteries face challenges in maintaining uniform thermal histories across cells to prevent thermal runaway propagation, requiring materials that provide low thermal resistance at normal temperatures but high resistance at elevated temperatures without significant dimensional changes.
Innovation Solution
A thermal management assembly featuring an expandable material with intumescent particles that expands at adverse temperatures, causing shear delamination at the thermally interruptible interface to reduce thermal conductance, allowing for effective heat dissipation during normal operation while preventing thermal runaway.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If expandable material with intumescent particles is used to increase thermal resistance at elevated temperatures, then thermal runaway propagation is prevented, but large volumetric expansion can apply stress on battery cell walls or generate high pressure
Solution Approach 1:
The patent changes the thermal conductivity parameter of the thermal pathway dynamically by using an expandable material that transitions from a low thermal resistance state at normal temperatures to a high thermal resistance state at elevated temperatures. This parameter change occurs through the expansion mechanism that creates gaps and reduces thermal contact, thereby preventing thermal runaway propagation without requiring permanent structural changes.
Solution Approach 2:
The thermal pathway is designed to be dynamic rather than static. The expandable material continuously adjusts its thermal resistance based on temperature conditions, being thermally conductive during normal operation and thermally resistive during thermal events. This dynamic adaptation allows the system to optimize thermal management across different operating conditions.
2Reliability
If expandable material is used to provide high thermal resistance at elevated temperatures, then thermal conductance is reduced, but large dimensional changes are required which may compromise structural integrity
Solution Approach 1:
The patent achieves a dramatic change in thermal conductance parameter (reduction by up to 90%) through the expansion mechanism. The expandable material transitions from a compact, thermally conductive state to an expanded, thermally resistive state, creating gaps that interrupt heat flow paths between adjacent battery cells.
Solution Approach 2:
The thermal pathway employs a composite structure combining an expandable material with intumescent particles and a thermally conductive material. This composite design allows the material to exhibit both thermal conductivity during normal operation and thermal resistance during thermal events, achieving the desired dual functionality within a constrained dimensional envelope.
3Loss of energy
If thermal pathways provide low thermal resistance during normal operation, then heat dissipation is improved, but thermal runaway can propagate to neighboring cells
Solution Approach 1:
The thermal pathway dynamically adjusts its thermal resistance based on operating temperature. During normal operation, the expandable material remains in a compact state, maintaining good thermal contact and enabling efficient heat dissipation. When temperature rises during a thermal event, the material expands to create gaps, increasing thermal resistance and preventing runaway propagation.
Solution Approach 2:
The system exploits parameter changes in the expandable material's physical state and thermal conductivity as a function of temperature. The material transitions from a dense, thermally conductive configuration at low temperatures to a expanded, thermally resistive configuration at high temperatures, thereby optimizing heat management across different operational regimes.
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 solution effectively reduces thermal conductance by up to 90% at elevated temperatures, mitigating the risk of thermal runaway and maintaining structural integrity by minimizing dimensional changes, thus enhancing battery safety and performance.
Implementation Method 1
the expandable material comprises intumescent particles, wherein, if heated to at least a first onset temperature, the expandable material expands
Implementation Method 2
the expandable material comprises intumescent particles, wherein, if heated to at least a first onset temperature, the expandable material expands and causes at least partial shear delamination
Implementation Method 3
the thermal pathway has a thermal conductance between the first electrochemical cell and the heat sink
Data Source
AI summary
A thermal management assembly comprises an electrochemical cell, a heat sink, and a thermal pathway comprising a thermally interruptible interface interposed therebetween the electrochemical cell and the heat sink. The thermal pathway comprises an expandable material comprising intumescent particles. If heated to at least a first onset temperature, the expandable material expands and causes at least partial shear delamination at the first thermally interruptible interface. A composite thermal management article comprises a first layer comprising an expandable material comprising intumescent particles and a second layer comprising a thermal conductor material. The first and second layers contact each other at a thermally interruptible interface. If heated to at least a first onset temperature, the expandable material expands and causes at least partial shear delamination at the thermally interruptible