Heat-Spreading Current Collector for Pouch Cell Temperature Uniformity
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Solution Overview
Problem
Pouch-type battery cells experience excessive temperature gradients due to single-sided tab cooling, leading to reduced performance and non-homogeneous aging, with existing cooling systems either insufficiently addressing these gradients or increasing battery weight and bulk through immersion cooling.
Innovation Solution
Incorporating at least two conductive layers with heat spreading layers made of high thermal conductivity materials like pyrolytic carbon between them in the anode and cathode current collector layers to enhance heat transport and reduce temperature gradients within the electrode assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If single-sided tab cooling is used in pouch-type battery cells, then the battery structure remains simple and lightweight, but excessive temperature gradients are produced through active areas leading to reduced performance and non-homogeneous aging
Solution Approach 1:
The current collector layer is segmented into multiple sub-layers (first current collector sub-layer and second current collector sub-layer) with a heat spreading layer interposed between them. This segmentation allows the heat spreading layer to be positioned at the center of the active area, enabling more effective heat distribution from the tab cooling system across the entire active area, thereby reducing temperature gradients.
Solution Approach 2:
A heat spreading layer made of highly thermally conductive material (such as pyrolytic graphite) is introduced as an intermediary between the tab cooling system and the active areas. This heat spreading layer acts as a thermal mediator that rapidly distributes heat laterally across the active area, preventing localized overheating and reducing temperature gradients without requiring complex cooling systems.
2Temperature
If immersion cooling systems are used to reduce temperature gradients, then temperature homogeneity is improved, but the battery becomes heavier and bulkier
Solution Approach 1:
The invention extracts the essential heat spreading function from the bulky immersion cooling system and concentrates it into a thin heat spreading layer integrated within the electrode assembly. This thin layer provides the necessary thermal conductivity to achieve temperature homogeneity without the weight and volume penalties of external fluid baths or complex cooling systems.
Solution Approach 2:
The heat spreading layer is implemented as a thin film (typically tens to hundreds of micrometers thick) made of flexible highly thermally conductive material. This thin film structure provides effective heat spreading while maintaining the lightweight and compact characteristics of pouch-type batteries, avoiding the weight and bulk of immersion cooling systems.
3Temperature
If the current collector layer is increased in thickness to improve heat transport, then temperature gradients are reduced, but the nonelectrochemically active mass increases reducing energy density
Solution Approach 1:
The current collector structure is transformed into a composite multi-layer system consisting of conductive sub-layers and a highly thermally conductive heat spreading layer. This composite structure leverages the high thermal conductivity of materials like pyrolytic graphite to achieve superior heat transport efficiency without increasing the overall thickness or mass of the current collector, thereby maintaining high energy density.
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
This approach homogenizes temperatures across the active area, improving battery performance and longevity while maintaining a lightweight design by effectively managing heat distribution.
Implementation Method 1
heat spreading layers made of high thermal conductivity materials like pyrolytic carbon between them in the anode and cathode current collector layers to enhance heat transport and reduce temperature gradients
Data Source
AI summary
The present invention relates to an electrode assembly (100), comprising in a stacked manner a first anode layer (112), an anode current collector layer (114), a second anode layer (116), a separator layer (118), a first cathode layer (120), a cathode current collector layer (122), and a second cathode layer (124). In the electrode assembly (100) according to the present invention, the anode current collector layer (114) and/or the cathode current collector layer (122) comprises at least two conductive layers (122a, 122c) wherein between neighbouring pairs of conductive layers (122a, 122c), a respective heat spreading layer (122b) is interposed.