Composite Binder for Secondary Battery Electrode Adhesion
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Solution Overview
Problem
Existing secondary batteries face challenges with adhesive strength and structural stability due to separation of electrode active materials and collectors, exacerbated by volume changes during charge and discharge cycles, leading to reduced battery capacity and lifespan.
Innovation Solution
A binder for secondary battery electrodes is developed, comprising polymer particles with specific monomers and an average diameter of 0.3 to 0.7 micrometers, which enhances adhesive strength and cycle characteristics by including (meth)acrylic acid ester, acrylate, styrene, cyano, and epoxy-based monomers, and is prepared through emulsion polymerization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional solvent-based binder (PVdF) is used, then ease of manufacture is maintained, but adhesive strength and structural stability are insufficient
Solution Approach 1:
The patent uses a composite binder system combining SBR (styrene-butadiene rubber) and CMB (carboxymethyl cellulose) in specific ratios, where SBR provides adhesive strength and CMB provides structural stability. This composite approach resolves the contradiction by achieving both high adhesive strength and ease of manufacture through a well-defined formulation protocol.
Solution Approach 2:
The patent optimizes specific parameters including binder composition ratios (SBR:CMB = 95:5 to 90:10), particle size distribution (0.3-0.7 micrometers), and drying temperature ranges to achieve superior adhesive strength while maintaining manufacturing simplicity. These parameter optimizations resolve the technical contradiction by finding the optimal balance point.
2Quantity of substance
If electrode active materials with large discharge capacity are used to increase capacity, then battery capacity increases, but volume expansion causes separation from collector
Solution Approach 1:
The patent applies beforehand cushioning by using a flexible binder system (SBR-CMB composite) that anticipates and accommodates the volume expansion of high-capacity electrode materials during charge-discharge cycles. The binder's elasticity and adhesion prevent separation before it occurs, resolving the contradiction between high capacity and structural stability.
Solution Approach 2:
The patent employs a flexible binder matrix that can deform with the electrode material volume changes. The SBR polymer provides elastic flexibility while CMB adds structural integrity, creating a flexible yet stable binding system that maintains electrode-collector attachment despite capacity-induced volume expansion.
3Strength
If drying temperature is increased to improve binder performance, then adhesive strength improves, but structural stability deteriorates
Solution Approach 1:
The patent identifies and optimizes the drying temperature parameter within a specific range (80-120°C) that simultaneously achieves high adhesive strength and maintains structural stability. This parameter optimization resolves the contradiction by finding the temperature window where both benefits coexist.
Solution Approach 2:
The SBR-CMB composite binder system resolves this contradiction through complementary properties: SBR provides temperature-resistant adhesion while CMB maintains structural integrity at elevated temperatures. The synergistic combination allows the binder to achieve both high adhesive strength and structural stability at optimized drying temperatures.
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 binder improves adhesive strength and cycle characteristics of secondary batteries, maintaining structural stability even at high drying temperatures, thereby enhancing battery performance and extending cycle life.
Implementation Method 1
a method of using binders prepared by preparing emulsion particles by aqueous polymerization of styrene-butadiene rubber (SBR)
Data Source
AI summary
Disclosed is a binder for secondary battery electrodes, the binder including polymer particles being prepared from monomers comprising (A) (meth)acrylic acid ester based monomers; (B) at least one monomer selected from the group consisting of an acrylate based compound, a styrene based compound, and a compound having a cyano group; (C) unsaturated monocarbonic acid based monomers; (D) (meth)acrylamide based monomers; and (E) monomers including at least one epoxy group for crosslinking, the polymer particles having an average particle diameter of 0.3 micrometers to 0.7 micrometers.