Binder-Coated Battery Current Collector for Fast-Charging Electrodes
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Solution Overview
Problem
Current rechargeable lithium batteries face challenges in achieving high-rate charging characteristics and cycle-life due to the insulating nature of polymer binders, which reduce electrical conductivity and block pores, affecting lithium ion movement and adhesion between the electrode active material layer and the current collector.
Innovation Solution
A current collector with a binder coating layer using a water-soluble binder, such as rubber-based or polymer resin binders, is applied to improve adhesion and electrochemical properties, combined with an electrode active material layer that includes a polymer binder with an ionic polymer to enhance electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polymer binders are used in the electrode, then adhesion between electrode active material and current collector is improved, but electrical conductivity is reduced and pores are blocked
Solution Approach 1:
The patent applies different binder types in different locations: a water-soluble binder (first binder) is applied to the current collector surface, while a non-water-soluble binder (second binder) is used in the electrode active material layer. This local differentiation allows the water-soluble binder to provide adhesion without significantly impacting conductivity, as it is confined to the collector interface rather than throughout the electrode structure.
Solution Approach 2:
The patent uses a composite binder system combining two different binder types with complementary properties. The water-soluble binder provides initial adhesion and processing benefits, while the non-water-soluble binder maintains structural integrity and minimizes conductivity loss. This composite approach leverages the strengths of each binder type to simultaneously improve adhesion and maintain electrical conductivity.
2Strength
If polymer binders are used in the electrode, then adhesion between electrode active material and current collector is improved, but lithium ion movement through pores is reduced
Solution Approach 1:
By confining the water-soluble binder primarily to the current collector interface rather than distributing it throughout the electrode pores, the patent minimizes pore blocking while maximizing adhesion at the critical collector-electrode interface. This localized application allows lithium ions to move freely through the electrode pores without significant obstruction from binder materials.
3Ease of manufacture
If conventional binders are used, then manufacturing process is simple, but electrochemical performance such as high-rate charging is poor
Solution Approach 1:
The patent changes the chemical and physical parameters of the binder system by selecting binders with specific properties: water solubility for the first binder enables aqueous processing and good adhesion, while the non-water-soluble nature of the second binder ensures minimal interference with electrochemical reactions. These parameter selections optimize both manufacturing ease and electrochemical performance including high-rate charging capabilities.
Data Source
AI summary
A current collector for a rechargeable lithium battery includes a substrate and a binder coating layer on a surface of the substrate, wherein the binder coating layer includes a water-soluble binder selected from a rubber-based binder, a polymer resin binder, or a combination thereof.