Silicon-Based Battery Anode Binder Ratios for Expansion and Adhesion
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Solution Overview
Problem
Silicon-based active materials in anodes for secondary batteries face challenges in maintaining excellent capacity, lifespan, and resistance characteristics due to their high volumetric expansion rates, which are difficult to suppress while ensuring energy density and battery performance.
Innovation Solution
An anode design incorporating a silicon-based active material with an acrylate-based binder and a rubber-based binder containing an acrylate-based monomer, where the content ratio of the acrylate-based monomer in the rubber-based binder is between 4 mol% and 80 mol%, effectively suppressing volumetric expansion and enhancing adhesive force and resistance characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a silicon-based active material is applied to increase discharge capacity, then energy density is improved, but volumetric expansion rate increases causing poor lifespan and resistance characteristics
Solution Approach 1:
The patent uses a composite binder system combining acrylate-based binder and rubber-based binder with specific content ratios to create a composite material structure that simultaneously addresses volumetric expansion and maintains reliability. The acrylate-based binder (5-50 wt%) provides expansion suppression while the rubber-based binder (5-45 wt%) ensures adhesion and lifespan characteristics, resolving the contradiction between energy density improvement and reliability maintenance
Solution Approach 2:
The patent changes the chemical composition parameters of the binder system by specifying precise content ratios of acrylate-based monomer (4-80 mol%) in the rubber-based binder and the weight ratio of acrylate-based to rubber-based binder (0.1-10). These parameter changes optimize the binder's ability to suppress volumetric expansion while maintaining adhesion, thereby improving both energy density and lifespan characteristics simultaneously
2Use of energy by moving object
If a silicon-based active material is applied to increase discharge capacity, then energy density is improved, but resistance characteristics deteriorate
Solution Approach 1:
The composite binder system with acrylate-based binder (5-50 wt%) and rubber-based binder (5-45 wt%) creates a dual-function material that suppresses volumetric expansion and maintains low resistance. The specific composition ratios ensure that the anode mixture layer maintains good electrical contact and ion transport pathways, resolving the contradiction between energy density improvement and resistance characteristics
Solution Approach 2:
By optimizing the weight ratio of acrylate-based to rubber-based binder (0.1-10) and the acrylate-based monomer content (4-80 mol%), the patent adjusts the binder's physical and chemical properties to minimize resistance. This parameter optimization ensures that the high-capacity silicon-based anode maintains excellent resistance characteristics while achieving high energy density
3Reliability
If volumetric expansion is suppressed to improve lifespan characteristics, then adhesion may be compromised
Solution Approach 1:
The patent employs a composite binder system where acrylate-based binder (5-50 wt%) provides volumetric expansion suppression and rubber-based binder (5-45 wt%) provides adhesion. This composite approach allows each binder component to perform its specialized function, resolving the contradiction between lifespan characteristics and adhesive force by combining materials with complementary properties
Solution Approach 2:
The patent optimizes the weight ratio of acrylate-based to rubber-based binder (0.1-10) to balance expansion suppression and adhesion. By adjusting this ratio, the binder system achieves sufficient adhesive force to maintain electrode integrity while simultaneously suppressing volumetric expansion to ensure long lifespan characteristics
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 proposed anode structure effectively suppresses volumetric expansion of silicon-based active materials, improves adhesive force between the current collector and the anode mixture layer, and reduces battery resistance, resulting in enhanced capacity, lifespan, and resistance characteristics.
Implementation Method 1
an anode mixture layer disposed on at least one surface of the anode current collector, wherein the anode mixture layer includes a silicon-based active material, an acrylate-based binder, and a rubber-based binder
Implementation Method 2
the rubber-based binder includes an acrylate-based monomer, and wherein a content ratio of the acrylate-based monomer in the rubber-based binder is greater than 4 mol% and less than 80 mol%
Data Source
Figure 1~2
AI summary
An anode for a secondary battery including an anode current collector and an anode mixture layer disposed on at least one surface of the anode current collector, wherein the anode mixture layer includes a silicon-based active material, an acrylate-based binder, and a rubber-based binder, wherein the rubber-based binder includes an acrylate-based monomer, and wherein a content ratio of the acrylate-based monomer in the rubber-based binder is greater than 4 mol% and less than 80 mol% is disclosed.