Thermal Incident Detection Using Anisotropic Material
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Solution Overview
Problem
Lithium battery cells in multi-cell modules and packs are susceptible to thermal runaway, leading to extreme heat build-up, fire, or explosion due to passive propagation, posing safety risks for drivers and passengers in electric vehicles.
Innovation Solution
A thermal incident detection apparatus using a thermally anisotropic material, such as graphite, positioned near battery cell vents, combined with sensors to detect abnormal thermal energy, allowing for early detection and implementation of safety measures to prevent propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional thermal sensors are placed directly near battery cells, then thermal runaway can be detected, but the sensors may be damaged by extreme heat and false alarms increase
Solution Approach 1:
A thermally anisotropic material is introduced as an intermediary between the battery cell and the thermal sensor. This material captures thermal energy from the cell vent and conducts it along its high-conductivity plane to the sensor, allowing the sensor to detect thermal incidents without being directly exposed to the extreme heat and pressure at the cell vent.
Solution Approach 2:
The thermally anisotropic material utilizes directional thermal conductivity, conducting heat primarily in the in-plane direction rather than through-plane. This dimensional differentiation allows thermal energy to be redirected along a safe path to the sensor, protecting the sensor from direct thermal exposure while maintaining detection capability.
2Measurement precision
If more thermal sensors are deployed in the battery pack, then detection coverage is improved, but device complexity and cost increase
Solution Approach 1:
The thermally anisotropic material serves multiple functions: it acts as a thermal conductor to transport heat to the sensor, a protective barrier to shield the sensor from extreme conditions, and a signal amplifier to enhance thermal energy transfer. This multi-functionality reduces the need for additional specialized components.
Solution Approach 2:
The thermally anisotropic material passively performs thermal management and signal conditioning functions without requiring external power or control systems. The material's inherent anisotropic thermal conductivity automatically directs heat flow to the sensor, eliminating the need for active thermal management systems.
3Loss of time
If thermal sensors are positioned close to battery cells for early detection, then response time is reduced, but the sensors are exposed to pressure waves and physical damage
Solution Approach 1:
The thermally anisotropic material is positioned between the battery cell vent and the thermal sensor to provide beforehand protection. It absorbs and redirects the force of pressure waves and physical ejections during thermal runaway, cushioning the sensor from direct exposure to these harmful physical effects while maintaining thermal detection capability.
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 enables early detection of thermal incidents, reducing the risk of fires and explosions by rapidly identifying and isolating affected cells, thereby enhancing safety for electric vehicle occupants and bystanders.
Implementation Method 1
a thermally anisotropic material positioned in proximity to one or more of the battery cells, the anisotropic material having an in-plane thermal conductivity greater than a through-plane thermal conductivity
Implementation Method 2
a thermally anisotropic material having an in-plane thermal conductivity greater than a through-plane thermal conductivity
Data Source
AI summary
Devices, methods and systems used to detect thermal incidents are disclosed. In one embodiment, there may be a thermal incident detection apparatus for a battery pack including one or more battery modules, the one or more battery modules comprising a plurality of battery cells arranged in a plurality of rows, wherein each battery cell in the one or more battery modules comprises a vent, the apparatus comprising a thermally anisotropic material positioned in proximity to one or more battery cells of the one of more battery modules, wherein the thermally anisotropic material has an in-plane thermal conductivity greater than a through-plane thermal conductivity; and a sensor positioned in proximity to the thermally anisotropic material to sense thermal energy transferred by one of more of the battery cells to the thermally anisotropic material.