Battery Electrode Barrier Layer with Mixed Conductive Powders
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Solution Overview
Problem
The use of aqueous active material compositions in battery electrodes can lead to decreased battery capacity and reduced discharge characteristics due to increased initial internal resistance, particularly when lithium-nickel oxide or other lithium-transition metal oxides are used, as they react with water, forming high-electrical-resistance compounds on the collector surface.
Innovation Solution
A barrier layer containing a conductive material and a water-insoluble polymer is applied on the collector surface, comprising a combination of first and second conductive powders with different particle diameters, where the first conductive powder has a predetermined average particle diameter and the second conductive powder has a larger diameter, ensuring improved conductivity while maintaining water resistance, thereby preventing the formation of high-electrical-resistance compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If aqueous active material composition is used to reduce environmental impact and material costs, then environmental friendliness and cost are improved, but initial internal resistance increases due to formation of high-electrical-resistance compounds on the collector surface
Solution Approach 1:
The barrier layer acts as an intermediary between the aqueous active material composition and the collector surface. It prevents direct contact between water and the collector, thereby preventing formation of high-electrical-resistance compounds, while still allowing the use of environmentally friendly and cost-effective aqueous compositions.
Solution Approach 2:
The barrier layer is formed on the collector surface before application of the aqueous active material composition. This preliminary action prevents the harmful reaction between water and the collector surface, ensuring low initial internal resistance from the outset while enabling use of aqueous compositions.
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
This configuration enhances the conductivity and water resistance of the barrier layer, resulting in a high-performance electrode that maintains stable performance even when using an aqueous active material composition, effectively preventing the formation of high-electrical-resistance compounds and improving battery output.
Implementation Method 1
providing a layer containing an organic solvent-soluble polymer (binder) and a conductive material (conductive layer) on the surface of the collector, and using this layer as a barrier layer to block direct contact between the collector and water
Implementation Method 2
Such a barrier layer must have both water-resistance (the property of blocking direct contact between water and the collector to prevent production of high-electrical-resistance compounds) and electrical conductivity
Data Source
AI summary
Disclosed is an electrode (30) (for example, a positive electrode for a lithium ion battery), wherein an active material layer (35) mainly composed of an electrode active material is supported by a metal collector (32). A barrier layer (33) containing a conductive material (330) and a water-insoluble polymer material (334) are formed on the surface of the metal collector (32). The conductive material (330) contains at least a first conductive powder (331) having a certain average particle diameter, and a second conductive powder (332) having an average particle diameter larger than that of the first conductive powder. The ratio of the first conductive powder (331) contained in the barrier layer (33) is higher than that of the second conductive powder (332).