Secondary Battery Electrode Binder for Metal Elution Suppression
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Solution Overview
Problem
The elution of metal components from electrode active materials in secondary batteries, particularly during repeated charge and discharge cycles at high voltages, leads to reduced durability and performance of the batteries.
Innovation Solution
An electrode for a secondary battery is developed, comprising a current collector with a mixture layer that includes an electrode active material containing a metal element, a compound with a CN group at the terminal, a conductive agent, a water-insoluble additive, and a water-soluble additive, specifically a polysaccharide, which inhibits metal elution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polysaccharide is added as a binder into a positive electrode, then metal component elution is trapped to some extent, but metal elution during high-voltage charge and discharge is not sufficiently inhibited
Solution Approach 1:
The patent combines polysaccharide (water-soluble additive) with a compound having a CN group at the terminal (water-insoluble additive) to form a composite binder system. This composite material leverages the water-solubility and film-forming capability of polysaccharide alongside the high-voltage stability and metal-trapping ability of the CN-group compound, achieving effective metal elution inhibition during high-voltage charge and discharge cycles.
Solution Approach 2:
The compound with a terminal CN group acts as an intermediary substance that specifically interacts with eluted metal ions. The CN groups serve as trapping sites that capture metal components before they can precipitate on the negative electrode or separator, while the polysaccharide provides the binder function and forms the matrix that holds this trapping mechanism in place.
2Quantity of substance
If transition metal oxide is used as positive electrode active material, then high capacity is achieved, but metal elution occurs during repeated charge and discharge
Solution Approach 1:
The patent converts the harmful metal elution phenomenon into a beneficial trapping mechanism. The CN-group compound is designed to actively capture and retain the metal ions that would otherwise elute from the transition metal oxide, transforming the problem of metal dissolution into a controlled trapping process that prevents precipitation on the negative electrode.
Solution Approach 2:
The CN-group compound serves as an intermediary that mediates between the transition metal oxide and the electrolyte/negative electrode system. It intercepts metal ions released from the active material and prevents them from reaching harmful deposition sites, thereby maintaining the benefits of high-capacity transition metal oxides while eliminating their primary drawback.
3Power
If high voltage charge and discharge is performed, then energy density is improved, but metal elution is significantly increased
Solution Approach 1:
The patent changes the chemical parameters of the binder system by introducing a compound with a terminal CN group, which has specific affinity for metal ions. This parameter change in the binder composition enables the system to withstand high-voltage conditions without excessive metal elution, allowing high energy density operation while maintaining electrode integrity.
Solution Approach 2:
The composite binder system combines the electrical stability and film-forming properties of polysaccharide with the metal-trapping capability of the CN-group compound. This composite material provides the dual functionality needed to support high-voltage charge and discharge while preventing metal elution, thereby enabling high energy density without the harmful side effects.
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 proposed electrode effectively inhibits the elution of metal components, thereby enhancing the durability and performance of secondary batteries, especially during high-voltage charge and discharge cycles.
Implementation Method 1
the compound having a CN group at a terminal... inhibits the metal elution
Data Source
AI summary
Provided are: a secondary battery electrode in which elution of a metal component is suppressed; and a secondary battery using this electrode. This secondary battery comprises a positive electrode and a negative electrode. At least the positive electrode or the negative electrode includes a collector, and a composite layer disposed on a surface of the collector. The composite layer includes an electrode active material containing an elemental metal, a compound having a terminal CN group, an electroconductive material, a water-insoluble additive, and a water-soluble additive. The water-insoluble additive contains a polysaccharide.