Thick Electrode Composition Balancing Peel Strength and Output Power
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Solution Overview
Problem
The long-term output power of power storage devices with thick active material layers containing carbon nanotubes is compromised due to reduced ion conductivity and increased bending, while the peel strength of the active material layer to the current collector is enhanced by carbon nanotubes, leading to decreased performance.
Innovation Solution
An electrode design with a current collector having a carbon coat layer and an active material layer containing 0.035% to 0.08% single-walled carbon nanotubes, styrene-butadiene rubber as an aqueous binder, and an active material content of 96% by mass, with a thickness of 250 μm or more, enhances peel strength and ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the active material layer contains carbon nanotubes to enhance peel strength, then the peel strength of the active material layer to the current collector is improved, but the long-term output power of the power storage device decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the carbon nanotube content within a specific range (0.03-0.08 mass%) and the active material layer thickness (250 μm or more). This quantitative parameter optimization resolves the contradiction by finding the optimal balance point where peel strength is sufficiently enhanced while the negative impact on long-term output power is minimized.
Solution Approach 2:
The patent uses composite materials by combining carbon nanotubes with the active material matrix in a controlled composition. The carbon nanotubes serve as conductive additives that enhance both mechanical strength and electrical conductivity, thereby improving peel strength while maintaining or enhancing long-term output power performance when used in the optimal concentration range.
2Quantity of substance
If the thickness of the active material layer is increased to enhance energy density, then the energy density of the power storage device is improved, but the long-term output power decreases when carbon nanotubes are present
Solution Approach 1:
The patent applies parameter changes by optimizing multiple parameters simultaneously: active material layer thickness (250 μm or more), carbon nanotube content (0.03-0.08 mass%), and binder content (1.2-1.8 mass%). This multi-parameter optimization resolves the contradiction by finding the optimal combination that maximizes energy density while maintaining long-term output power.
Solution Approach 2:
The patent applies local quality by ensuring uniform distribution of carbon nanotubes and binder throughout the thick active material layer. This localized optimization of material properties ensures that even in thick layers (250 μm or more), the conductive network and mechanical integrity are maintained uniformly, preventing the degradation of long-term output power while achieving 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
The electrode design improves the long-term output power and peel strength of the power storage device, maintaining high energy density and reducing bending-induced ion conductivity loss.
Implementation Method 1
the active material layer contains conductive fibers, as a conductive aid for enhancing electron conductivity in the active material layer
Implementation Method 2
the peel strength of the active material layer to the current collector provided with a carbon coat layer is enhanced by causing the active material layer of the electrode to contain carbon nanotubes
Data Source
AI summary
An electrode (100) for a power storage device includes a current collector (101) having a first surface (101a), and an active material layer (102) that is formed on the first surface (101a) of the current collector (101). A thickness of the active material layer (102) is 250 μm or more. A carbon coat layer (C) is provided on the first surface (101a) of the current collector (101). The active material layer (102) contains an active material that can store and release charge carriers, an aqueous binder, and single-walled carbon nanotubes. A content of the single-walled carbon nanotubes in the active material layer (102) is in a range of 0.035% by mass to 0.08% by mass.