Graphite Foil Battery Pack Heating for Uniform Cell Temperature
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Solution Overview
Problem
Lithium-ion batteries face issues with non-uniform thermal distribution, leading to lithium plating, uneven wear, and performance degradation due to temperature differentials within battery packs, which existing heating solutions fail to adequately address.
Innovation Solution
A temperature control element utilizing anisotropic materials like graphite, graphene, or carbon nanotubes, integrated with structural elements and tabs, to create controllable temperature regions within battery packs, ensuring even heating and cooling across electrochemical cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If common algorithmic heating solutions are used, then heating capability is provided, but thermal distribution becomes non-uniform with preferential warming of terminal areas
Solution Approach 1:
The patent applies local quality by using anisotropic materials with directionally dependent thermal conductivity properties. The material structure is engineered to conduct heat preferentially in specific directions (e.g., along the battery length) while limiting heat transfer in other directions, thereby achieving uniform thermal distribution across different battery regions including terminals, bottom, and sides.
Solution Approach 2:
The patent employs asymmetric thermal conduction characteristics through anisotropic materials where thermal conductivity differs along different axes. This asymmetric heat flow pattern counteracts the natural tendency for heat to concentrate at terminal areas, redistributing thermal energy more evenly throughout the battery pack structure.
2Productivity
If non-uniform thermal distribution occurs, then heating efficiency is improved in terminal areas, but lithium plating and uneven wear increase at cell bottom and sides
Solution Approach 1:
The anisotropic heating element provides locally optimized heat transfer by conducting thermal energy preferentially along the battery length direction. This ensures that heat reaches cell bottom and side regions that are otherwise thermally isolated, preventing lithium plating and uneven wear while maintaining overall heating efficiency.
Solution Approach 2:
The anisotropic material acts as an intermediary thermal conduction medium between the heating source and the battery cells. It mediates heat distribution by channeling thermal energy along specific pathways to reach areas that would otherwise be thermal bottlenecks, thereby preventing localized harmful effects.
3Power
If internal cells are positioned in a stack configuration, then overall output is increased, but thermal resistance increases for internal cells compared to external cells
Solution Approach 1:
The heating system is segmented into multiple anisotropic heating elements positioned at different locations within the battery pack. This segmentation allows each element to independently address the thermal needs of specific cell groups, ensuring that internal cells receive adequate thermal management despite their higher thermal resistance.
Solution Approach 2:
The patent employs asymmetric thermal conduction pathways tailored to the stack configuration. Internal cells, which experience higher thermal resistance, are provided with enhanced thermal conduction paths through the anisotropic materials that preferentially direct heat flow toward these thermally isolated regions, balancing temperature distribution across the entire stack.
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 prevents lithium plating and improves temperature performance by maintaining uniform cell temperatures, enhancing the lifespan and efficiency of lithium-ion batteries.
Implementation Method 1
The one or more anisotropic elements may each include one or more anisotropic materials... configured to be in a heat transfer relationship with the electrochemical cell so as to heat and/or cool the electrochemical cell
Implementation Method 2
The temperature control element may be configured to be in a heat transfer relationship with the electrochemical cell so as to heat and/or cool the electrochemical cell
Data Source
AI summary
The present disclosure relates a temperature regulating system including an anisotropic material for use as a heating material or element (e.g., an active heater) and a cooling material or element (e.g., passive cooling) in a battery pack including one or more electrochemical cells. The temperature regulating system includes one or more temperature control elements. Each temperature control element is configured to be in a heat transfer relationship with one or more electrochemical cells so as to heat and/or cool the one or more electrochemical cells of the battery pack. Each temperature control element includes two or more structural elements and one or more anisotropic elements disposed between the two or more structural elements. The temperature control elements may be disposed between the electrochemical cells of the stack, disposed around the electrochemical cells of the stack, or both.