Core-Shell Binder for Secondary Battery Electrodes
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Solution Overview
Problem
Conventional binders for secondary battery electrodes lack sufficient adhesive strength and structural stability, leading to decreased charge/discharge capacity and lifespan due to electrode active material separation and volume changes during repeated cycles.
Innovation Solution
A binder with a core-shell structure is developed, where the core is styrene-butadiene rubber (SBR) and the shell is a copolymer of specific monomers, including functional groups that enhance binding capacity and reduce electrolyte swelling, thereby improving adhesive strength and structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional binders (PVdF or SBR) are used, then the binder provides basic adhesive function, but the adhesive strength and adhesive durability are insufficient leading to electrode material separation during charge/discharge cycles
Solution Approach 1:
The patent applies composite materials by combining SBR core particles with a shell layer formed from copolymerized monomers (acrylic acid, itaconic acid, and vinyl-based monomers). This core-shell composite structure integrates the elasticity of SBR with the adhesive functionality of the shell layer, achieving both strong initial adhesion and durable bonding that prevents electrode material separation during charge/discharge cycles.
Solution Approach 2:
The patent applies local quality by creating a core-shell structure where different regions have different functions: the SBR core provides elasticity and volume change accommodation, while the shell layer with carboxylic acid functional groups provides strong adhesive bonding to electrode materials. This localized functional differentiation resolves the contradiction between basic adhesion and durable adhesion.
2Strength
If the binder has strong adhesive strength, then electrode material separation is prevented, but the binder must maintain flexibility to accommodate volume changes during charge/discharge cycles
Solution Approach 1:
The core-shell composite structure combines materials with complementary properties: the SBR core provides flexibility and elasticity to accommodate volume changes, while the shell layer provides strong adhesive strength. This composite approach resolves the contradiction between maintaining strong bonds and allowing volume expansion/contraction during lithium ion insertion and elimination.
Solution Approach 2:
The binder is segmented into distinct core and shell regions with different functions. The SBR core handles mechanical deformation and volume changes, while the shell layer maintains strong adhesive bonds. This segmentation allows each component to optimize its function without compromising the other, solving the contradiction between adhesive strength and volume adaptability.
3Object-affected harmful factors
If eco-friendly binders (aqueous polymerization of SBR) are used, then environmental friendliness and reduced binder amount are achieved, but adhesive durability is not dramatically improved
Solution Approach 1:
The patent creates a composite binder system that maintains the eco-friendly aqueous polymerization process while dramatically improving adhesive durability. The core-shell structure with carboxylic acid functional groups in the shell layer provides enhanced bonding to electrode materials, overcoming the limitation of conventional SBR binders while retaining environmental benefits.
Solution Approach 2:
The patent modifies the chemical parameters of the binder by introducing carboxylic acid functional groups (through acrylic acid and itaconic acid copolymerization) into the SBR structure. This parameter change transforms the binder from having merely elastic properties to having both adhesive and durable bonding capabilities, while maintaining the eco-friendly aqueous processing method.
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 core-shell binder significantly enhances cycle characteristics and adhesive strength, leading to improved battery performance and extended lifespan by reducing electrolyte swelling and maintaining structural integrity during charge/discharge cycles.
Implementation Method 1
the binder includes a functional group providing binding capacity to surfaces of the SBR particles
Implementation Method 2
the core-shell binder significantly enhances cycle characteristics and adhesive strength, leading to improved battery performance and extended lifespan by reducing electrolyte swelling and maintaining structural integrity during charge/discharge cycles
Data Source
AI summary
Disclosed are a binder with a core-shell structure for a secondary battery electrode, and a secondary battery including the same, wherein the core includes styrene-butadiene rubber (SBR), the shell includes a copolymer of two or more monomers selected from the group consisting of a conjugated diene-based monomer, a (meth)acrylic ester-based monomer, an acrylate-based monomer, a vinyl-based monomer, a nitrile-based monomer, and an ethylenically unsaturated carboxylic acid monomer, and the binder includes a functional group providing binding capacity to surfaces of the SBR particles. Such a binder provides excellent adhesive strength and elasticity and, thus, overall performance of a secondary battery including the same may be improved.