Electrode Plate With Graded Conductive Agent for Thin Current Collectors
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Solution Overview
Problem
Lithium-ion batteries face challenges in achieving high mass and volume energy density while maintaining good electrochemical performance, safety, and processing performance due to limitations in current collector design, particularly with composite current collectors that have poor conductivity and are prone to damage.
Innovation Solution
The electrode active material layer is divided into inner and outer regions with varying conductive agent content, enhancing conductivity and binding force between the current collector and the active material layer, and a composite current collector with a thinner conductive layer is used, supported by a polymer material with a specific thickness range, and optionally a protective layer to improve mechanical strength and prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a metal-plated plastic current collector is used to reduce weight and increase energy density, then mass and volume energy density are improved, but processing performance, safety performance, and electrical performance deteriorate
Solution Approach 1:
The patent uses a composite current collector structure consisting of a plastic substrate layer and a metal plating layer. This composite structure allows the plastic substrate to provide lightweight properties and energy density improvement, while the metal plating layer restores and enhances electrical conductivity, mechanical strength, and processing performance. The combination resolves the contradiction by integrating the advantages of both materials while mitigating their individual disadvantages.
2Quantity of substance
If the thickness of the conductive layer in the composite current collector is reduced to improve energy density, then mass energy density is improved, but conductivity and mechanical strength deteriorate
Solution Approach 1:
The patent optimizes the thickness parameter of the metal plating layer within a specific range (5-100 nm) to achieve the best balance between conductivity, mechanical strength, and energy density. By precisely controlling this parameter, the invention maintains sufficient electrical performance and structural integrity while minimizing the weight contribution of the conductive layer, thereby improving mass energy density.
3Quantity of substance
If the conductive layer is made thinner to reduce weight, then mass energy density is improved, but the conductive layer becomes more prone to damage
Solution Approach 1:
The patent employs a composite structure where the plastic substrate layer serves as a robust foundation that protects the thin metal plating layer from mechanical damage. The substrate provides the necessary mechanical strength and durability, allowing the metal layer to be kept thin for weight reduction while the overall composite structure maintains adequate strength and damage resistance.
4Quantity of substance
If a perforated current collector is used to reduce weight, then mass energy density is improved, but processing performance and electrical performance deteriorate
Solution Approach 1:
The patent uses a continuous, uniform metal plating layer on the plastic substrate without perforations or discontinuities. This homogeneous structure ensures consistent electrical conductivity across the entire current collector surface and maintains good processing performance during electrode manufacturing, while still achieving weight reduction through the use of lightweight plastic material and thin metal plating.
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 configuration reduces internal resistance, increases power performance, prevents significant polarization and lithium precipitation during long-term cycling, and enhances the reliability and safety of the battery cell.
Implementation Method 1
the conductive layer has a single-sided thickness D2 that satisfies: 30 nm≤D2≤3 μm... improving electron transmission efficiency and reducing the electrical resistance between the current collector and the electrode active material layer
Implementation Method 2
the electrode active material layer comprises an electrode active material, a binder and a conductive agent... improve the binding force between the current collector and the electrode active material layer
Data Source
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AI summary
The present application relates to the field of battery, and more particularly, to an electrode plate and an electrochemical device. The electrode plate according to the present application includes a current collector and an electrode active material layer disposed on at least one surface of the current collector, wherein the current collector includes a support layer and a conductive layer disposed on at least one surface of the support layer, the conductive layer has a single-sided thickness D2 satisfying: 30 nm≤D2≤3 µm; and the electrode active material layer includes an electrode active material, a binder and a conductive agent; and the conductive agent is unevenly distributed in the electrode active material layer in a thickness direction of the electrode active material layer, in which the weight percentage of the conductive agent in the inner region of the electrode active material layer is higher than the weight percentage content of the conductive agent in the outer region of the electrode active material layer based on the total weight of the electrode active material layer, and the binder in the inner region of the electrode active material layer includes a water-dispersible binder. The electrode plate of the present application has good workability, and the electrochemical device including the electrode plate has high energy density, good electrical performance and long-term reliability.