Silicon Anode Binder System Suppressing Electrode Swelling
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Solution Overview
Problem
The existing binder resin compositions for lithium ion secondary batteries, particularly when using silicon-based active materials, fail to adequately suppress swelling of the negative electrode, leading to suboptimal cycle and rate characteristics.
Innovation Solution
A negative electrode slurry composition is developed using a combination of styrene-butadiene copolymer latex and acryl polymer latex as binder resins, along with a carbon-based and silicon-based active material, where the styrene-butadiene copolymer latex has a gel amount of 70 to 98% and a glass transition temperature of −30° C. to 60° C., and the acryl polymer latex has a gel amount of 70 to 98% and a glass transition temperature of −100° C. to 0° C., effectively reducing swelling during charge-discharge cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a silicon-based active material is used alone for a negative electrode active material, then the capacity of the lithium ion secondary battery is increased, but the swelling of the negative electrode cannot be sufficiently suppressed, resulting in poor cycle and rate characteristics
Solution Approach 1:
The patent employs a composite binder resin system combining styrene-butadiene copolymer latex (A) with gel amount of 70-98% and glass transition temperature of -30°C to 60°C, and acryl polymer latex (B) with gel amount of 70-98% and glass transition temperature of -100°C to 0°C. This composite binder system effectively suppresses electrode swelling while maintaining high capacity, resolving the contradiction between battery capacity and cycle characteristic
Solution Approach 2:
The patent optimizes the glass transition temperature range of the binder resins to achieve optimal balance between electrode flexibility and structural stability. By controlling the gel amount (70-98%) and glass transition temperature (-30°C to 60°C for component A, -100°C to 0°C for component B), the binder maintains electrode integrity during silicon expansion, improving cycle characteristic while preserving capacity
2Quantity of substance
If a silicon-based active material is used alone for a negative electrode active material, then the capacity of the lithium ion secondary battery is increased, but the swelling of the negative electrode during charge-discharge cannot be sufficiently suppressed
Solution Approach 1:
The patent uses a composite binder resin system consisting of styrene-butadiene copolymer latex (A) and acryl polymer latex (B), both with gel amounts of 70-98%. This composite binder effectively constrains silicon-based active material expansion during lithiation, suppressing electrode swelling while maintaining high capacity
Solution Approach 2:
The patent controls the glass transition temperature of the binder resins within specific ranges (component A: -30°C to 60°C, component B: -100°C to 0°C) to optimize the binder's mechanical properties. This parameter optimization enables the binder to accommodate silicon volume changes without losing structural integrity, effectively suppressing electrode swelling
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 composition significantly suppresses swelling of the negative electrode, thereby enhancing the cycle and rate characteristics of lithium ion secondary batteries, ensuring improved performance and durability.
Implementation Method 1
a styrene-butadiene copolymer latex having a gel amount of 70 to 98% and a glass transition temperature of −30° C. to 60° C. in dynamic viscoelasticity measurement and (B) an acryl polymer latex having a gel amount of 70 to 98% and a glass transition temperature of −100° C. to 0° C.
Implementation Method 2
a glass transition temperature of −30° C. to 60° C. in dynamic viscoelasticity measurement and (B) an acryl polymer latex having a gel amount of 70 to 98% and a glass transition temperature of −100° C. to 0° C. in dynamic viscoelasticity measurement
Data Source
AI summary
Provided is a negative electrode slurry composition including a binder resin, a water-soluble polymer, and a negative electrode active material, wherein the binder resin including (A) a styrene-butadiene copolymer latex having a gel amount of 70 to 98% and a glass transition temperature of −30° C. to 60° C. in dynamic viscoelasticity measurement and (B) an acryl polymer latex having a gel amount of 70 to 98% and a glass transition temperature of −100° C. to 0° C. in dynamic viscoelasticity measurement, and the negative electrode active material including a carbon-based active material and a silicon-based active material.