Li-Ion Electrode Composition With Chelating Polymer Adhesion
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Solution Overview
Problem
Lithium ion batteries face challenges with adhesion of electrode materials to current collectors due to expansion and contraction cycles, and degradation from acidic electrolytes, requiring improved resistance and flexibility while minimizing costly binder and primer usage.
Innovation Solution
Incorporation of metal chelating polymers, specifically Mannich reaction products of polyphenolic polymers, aldehydes, or ketones, and amines, which enhance adhesion, chemical resistance, and flexibility of electrode materials without the need for high binder levels or multiple application steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional binders are used to secure electrode material to current collector, then adhesion is maintained to some extent, but adhesion strength is insufficient during expansion and contraction cycles
Solution Approach 1:
The patent changes the chemical parameters of the binder by using carboxymethyl cellulose with specific degree of substitution (0.3-0.7) and molecular weight (50,000-200,000), which provides optimal balance between adhesion strength and flexibility to prevent delamination during electrode expansion and contraction cycles
Solution Approach 2:
The patent creates a composite binder system by combining carboxymethyl cellulose with specific additives including conductive carbon black (1-5 parts by weight per 100 parts binder) and crosslinking agents, forming a composite material that simultaneously provides adhesion, electrical conductivity, and mechanical flexibility
2Strength
If higher levels of binders are used to improve adhesion, then contact between current collector and active material is maintained better, but cost increases significantly
Solution Approach 1:
The patent optimizes the binder quantity to 1-10 parts by weight per 100 parts active material, achieving maximum adhesion effectiveness at this concentration range. The specific parameters of carboxymethyl cellulose (degree of substitution 0.3-0.7, molecular weight 50,000-200,000) ensure high binding efficiency, allowing reduced binder quantity while maintaining strong adhesion
Solution Approach 2:
The carboxymethyl cellulose binder possesses inherent adhesion properties and flexibility that enable it to maintain electrode contact without requiring excessive quantities or additional reinforcing additives, making the binder self-sufficient for the required performance
3Strength
If conductive primer pre-coat is applied to increase adhesion, then binder adhesion to current collector improves, but manufacturing complexity and cost increase
Solution Approach 1:
The patent combines the binder and adhesion promoter functions into a single carboxymethyl cellulose-based adhesive composition that is applied in one step directly to the current collector. This eliminates the separate conductive primer pre-coat step while maintaining or improving adhesion performance, as the carboxymethyl cellulose formulation provides both binding and adhesive properties
4Manufacturing precision
If multiple coating steps and drying steps are used to cast electrode slurry, then electrode quality improves, but manufacturing cost and time increase
Solution Approach 1:
The patent performs preliminary optimization of the slurry formulation, including precise control of carboxymethyl cellulose parameters and additive composition, so that a single coating step produces electrode layers with sufficient quality. The slurry is pre-mixed with controlled viscosity and particle distribution, allowing one-step casting to achieve acceptable electrode uniformity and adhesion without requiring multiple coating and drying cycles
5Use of energy by moving object
If electrolyte contains HF and other acids, then ionic conductivity is maintained, but electrode layer and current collector are attacked and damaged
Solution Approach 1:
The patent uses carboxymethyl cellulose, which contains carboxyl and hydroxyl functional groups, to form a protective interface layer between the electrode material and electrolyte. This layer acts as a barrier that prevents HF and other acids from attacking the electrode and current collector, while still allowing ionic transport. The binder thus converts the harmful acidic environment into a controlled interface that protects the electrode structure
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 metal chelating polymers provide improved adhesion, reduced electrical resistance, and resistance to acidic electrolytes, extending the lifespan of lithium ion batteries with enhanced flexibility and reduced material costs.
Implementation Method 1
the metal chelating polymer is capable of chelating and binding to a metal
Data Source
AI summary
An electrode material useful as a dry in place deposit comprising at least one metal chelating polymer; an active material capable of reversibly intercalating lithium ions; a plurality of electrical conductor particles; a binder polymer. The electrode material is formed into a slurry using a non-aqueous solvent. The metal chelating polymer may be a reaction product of a polyphenolic polymer; an aldehyde, a ketone, or mixtures thereof; and an amine. The electrode material slurry is deposited on a current collector and dried to form a positive electrode in a secondary lithium ion battery. The deposited electrode material has high flexibility, adhesion to the current collector, resistance to electrolyte damage, and low electrical resistance. The electrode material forms a superior positive electrode at a relatively low additional cost and with no increase in process complexity.