Layered Electrode Plate with Polypropylene Binders for Ion Resistance
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Solution Overview
Problem
Current electrochemical devices, such as lithium-ion batteries, face limitations in safety performance and kinetic performance due to high transmission resistance and adverse effects on compacted density from binder materials, which affect the bonding strength and energy density.
Innovation Solution
The electrode plate design incorporates a layered structure with first and second composite particles, where the first composite particle is closer to the current collector, reducing lithium ion transmission resistance, and uses polypropylene as binder particles to enhance bonding strength while minimizing adverse effects on compacted density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If binder particles are used to bond active material particles to the current collector, then bonding strength is improved, but compacted density is adversely affected
Solution Approach 1:
The patent applies local quality by using different binder particles with different properties in different regions of the active material layer. Specifically, first binder particles with smaller particle diameters (0.01 μm to 1 μm) are used in the first active material layer closer to the current collector to ensure strong bonding, while second binder particles with larger particle diameters (1 μm to 10 μm) are used in the second active material layer farther from the current collector to maintain higher compacted density. This regional differentiation resolves the contradiction between bonding strength and compacted density.
2Quantity of substance
If the active material layer is made thicker to increase energy density, then energy storage capacity is improved, but lithium ion transmission resistance increases
Solution Approach 1:
The patent implements local quality by creating a layered structure where the first active material layer near the current collector has smaller particle diameters and lower binder content to minimize transmission resistance, while the second active material layer farther away has larger particle diameters and higher binder content to increase energy density. This spatial differentiation allows the overall layer to be thicker while maintaining low transmission resistance in the critical region near the current collector.
Solution Approach 2:
The patent resolves the contradiction by transitioning from a uniform single-layer structure to a multi-layered vertical structure. By organizing active material particles and binders in distinct layers at different positions in the thickness direction, the patent creates a dimensional solution where the first layer optimizes for ion transmission and the second layer optimizes for energy storage, thereby achieving both high energy density and low transmission resistance.
3Strength
If more binder material is used to enhance bonding, then bonding strength is improved, but kinetic performance deteriorates due to increased transmission resistance
Solution Approach 1:
The patent applies local quality by concentrating binder material strategically in the first active material layer where it is most needed for bonding to the current collector, while using less binder in the second active material layer where it would impede ion transmission. The first binder particles with smaller diameters provide effective bonding with minimal quantity, preserving kinetic performance in the bulk of the active material layer.
Data Source
AI summary
An electrode plate includes a current collector and an active material layer located on the current collector. The active material layer includes a first composite particle and a second composite particle. A first binder particle and all first active material particles in contact with the first binder particle constitute the first composite particle. A second binder particle and all second active material particles in contact with the second binder particle constitute the second composite particle. In a thickness direction of the active material layer, the first composite particle is closer to the current collector than the second composite particle. A number of the first active material particles contained in the first composite particle is smaller than a number of the second active material particles contained in the second composite particle. Both composition of the first binder particle and composition of the second binder particle include polypropylene. This electrode plate has increased an ohmic resistance of the active material layer and reduced an electrochemical reaction impedance.