Dynamic Cell Spacing Mechanism for Thermal Runaway Mitigation
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Solution Overview
Problem
Lithium-ion batteries are prone to thermal runaway, which can propagate from one cell to another, leading to safety concerns and potential failures in battery packs.
Innovation Solution
A spacer mechanism is introduced that senses elevated temperatures and increases the spacing between lithium-ion cells, using mechanisms like pantographs, telescopic screw drives, or intumescent materials to prevent heat transfer and propagation, employing sensors to detect thermal runaway precursors and activate the spacing mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If lithium ion cells are arranged closely in battery packs to maximize energy density, then productivity and space utilization are improved, but thermal runaway can propagate more easily from one cell to another, worsening safety and reliability
Solution Approach 1:
The patent incorporates a spacer mechanism that is pre-positioned between battery cells but remains inactive during normal operation. When thermal runaway is detected through temperature sensors, the spacer mechanism activates to increase spacing between cells. This preliminary positioning allows the system to maintain high energy density during normal use while having an ready-to-deploy safety mechanism that can quickly create thermal isolation barriers when needed.
2Reliability
If fixed spacing is maintained between cells to prevent thermal propagation, then safety is improved, but energy density and space utilization deteriorate
Solution Approach 1:
The patent employs a dynamic spacer mechanism that can change the spacing between battery cells based on operational conditions. During normal operation, cells maintain close proximity for optimal energy density. When thermal runaway is detected via temperature sensors, the spacer mechanism dynamically adjusts to increase spacing, creating thermal barriers. This dynamic adjustment allows the system to optimize for energy density during normal use while maintaining safety capabilities when needed.
3Reliability
If spacer mechanisms are added to battery packs to increase cell spacing and prevent thermal propagation, then safety and reliability are improved, but device complexity increases
Solution Approach 1:
The patent implements a self-activating spacer mechanism that uses temperature sensors to detect thermal runaway conditions and automatically triggers the spacing adjustment without requiring external control systems. The thermal expansion elements or shape memory materials inherently respond to temperature changes, causing the spacer to deploy autonomously. This self-service approach enhances safety while minimizing control system complexity.
Solution Approach 2:
The patent utilizes materials that undergo phase transitions in response to temperature changes, such as thermal expansion materials or shape memory alloys. When thermal runaway occurs and temperature rises, these materials transition from a compact state to an expanded state, automatically increasing the spacing between battery cells. This phase transition mechanism provides a simple, reliable way to activate the safety feature without complex control systems.
4Reliability
If cell spacing is increased to create airflow and cooling space, then thermal runaway propagation is prevented, but volume and energy density are reduced
Solution Approach 1:
The spacer mechanism is pre-positioned in a compact state within the available space between cells, allowing the battery pack to maintain high energy density during normal operation. When thermal runaway is detected, the spacer deploys to create the necessary airflow channels and cooling space. This preliminary positioning ensures that safety spacing is available when needed without permanently reducing the energy density of the battery pack.
Solution Approach 2:
The spacer mechanism dynamically adjusts the spacing between cells based on thermal conditions. During normal operation, cells are positioned closely together for optimal energy density. When thermal runaway is detected via temperature sensors, the spacer mechanism activates to increase spacing, creating thermal barriers and airflow channels. This dynamic adjustment allows the system to optimize for energy density during normal use while maintaining safety capabilities when needed.
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 mitigates the risk of thermal runaway by creating space for airflow and cooling, thereby delaying or preventing the propagation of thermal events across adjacent cells, enhancing the safety and reliability of lithium-ion battery packs.
Implementation Method 1
an intumescent material may be encapsulated in a heat resistant shell and used as a spacer mechanism to separate the lithium ion cells of a pack, and when one of the cells reaches a threshold temperature the neighboring (e.g., adjacent) intumescent shells will begin to expand, harden, and separate the distance between the hot cell
Implementation Method 2
a pantograph may be used as a spacer mechanism to separate the lithium ion cells of a battery pack when one of the cells reaches a threshold temperature
Implementation Method 3
a telescopic screw drive may be used as a spacer mechanism to separate the lithium ion cells of a battery pack when one of the cells reaches a threshold temperature
Data Source
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AI summary
Disclosed herein is an apparatus for controlling the spacing of battery cells. The apparatus monitors the temperature of the battery cells, and when a battery cell temperature value exceeds a threshold, changes the configuration of the battery cell spacing from an initial closed configuration to an open configuration using a spacer mechanism. The spacing during the closed configuration is a first distance between the battery cells, and during the open configuration is a second distance between the battery cells. The second distance is substantially large than the first distance to position the lithium ion cells further apart, lowering the probability a thermal runaway event propagating from one cell to adjacent cells. The spacer mechanism may include a telescoping or expanding frame, a motor, one or more sensors, and a controller configured to operate the mechanical spacer.