Composite Positive Current Collector for Wrinkle-Resistant Battery Electrodes
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Solution Overview
Problem
The composite current collectors for positive electrodes in secondary batteries face challenges with poor processability, leading to issues such as wrinkling, cracking, and reduced energy density, which hinder their application in high-energy-density applications like electric vehicles and energy storage systems.
Innovation Solution
A composite current collector design featuring an organic support layer with specific thickness, tensile strength, yield strength, and elastic modulus, combined with a conductive layer, where the ductility coefficient is optimized to enhance elongation and processability, thereby improving mechanical strength and reducing interface side reactions during charging and discharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a composite current collector with an organic support layer is used, then energy density is improved due to lighter density, but processability deteriorates with wrinkling and cracking issues
Solution Approach 1:
The patent applies parameter changes by precisely controlling the thickness of the organic support layer (3-15 μm) and the metal foil layer (6-18 μm), and by optimizing the ductility coefficient through selection of organic materials with specific mechanical properties (tensile strength 20-80 MPa, elongation at break 10-50%). These parameter optimizations resolve the contradiction by achieving both light weight for energy density and appropriate mechanical properties for processability
Solution Approach 2:
The patent uses composite materials by combining an organic support layer (polymer or organic-inorganic composite) with a metal foil layer (aluminum, copper, or their alloys). This composite structure leverages the light weight and flexibility of organic materials while incorporating the strength and conductivity of metals, thereby simultaneously improving energy density and processability
2Use of energy by moving object
If the support layer thickness is reduced to improve energy density, then manufacturing cost decreases, but mechanical strength and elongation deteriorate leading to more fractures
Solution Approach 1:
The patent applies parameter changes by establishing optimal thickness ranges for the organic support layer (3-15 μm) and metal foil layer (6-18 μm), and by controlling the ductility coefficient within 0.5-2.0. These parameter optimizations ensure that even at reduced thickness for energy density, the composite current collector maintains sufficient mechanical strength and elongation (15-40%) to prevent fractures during processing
3Productivity
If the ductility coefficient is increased to improve elongation and processability, then manufacturing yield increases, but the structural stability and resistance to deformation deteriorate
Solution Approach 1:
The patent applies parameter changes by optimizing the ductility coefficient within a balanced range of 0.5-2.0, rather than maximizing it. This balanced optimization, combined with controlling the organic support layer thickness (3-15 μm) and metal foil layer thickness (6-18 μm), achieves both improved manufacturing yield (reduced fractures and wrinkling) and maintained structural stability (resistance to deformation during winding and charging-discharging cycles)
Data Source
AI summary
This application provides a composite current collector for positive electrode including a support layer and a conductive layer disposed on at least one side of the support layer. The support layer is an organic support layer. The support layer has a thickness d1, a tensile strength at break T1, a yield strength Q1, and an elastic modulus G1; the conductive layer has a total thickness d2, a tensile strength at break T2, and an elastic modulus G2; and the composite current collector for positive electrode satisfies the following condition: (d1×T1−(d2×T2)×(1−α)−d1×Q1×α)≥800 Pa·m, where α=G1/(G1+G2).