Phosphate-Modified Iron Oxyhydroxynitrate for Cathode Adhesion
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Solution Overview
Problem
The capacity limitation of lithium secondary batteries, particularly in applications like electric vehicles, is due to material limitations of the positive electrode, and existing methods to improve the positive electrode in lithium-sulfur batteries, such as coating or adding porous materials, face issues like agglomeration and reduced adhesion, leading to decreased charging/discharging efficiency.
Innovation Solution
The use of iron oxyhydroxynitrate with hydrogen phosphate ions adsorbed on its surface as a positive electrode additive, which repels the carboxylate functional group of the binder, preventing agglomeration and enhancing adhesion, thereby improving the distribution and stability of the positive electrode active material layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If porous materials or coating layers are added to the positive electrode to prevent polysulfide dissolution, then the capacity and stability are improved, but agglomeration occurs between the binder and metal oxide, reducing adhesion and charging/discharging efficiency
Solution Approach 1:
The patent introduces a surface-modified metal oxide as an intermediary substance between the binder and the porous metal oxide additive. This surface-modified metal oxide prevents direct harmful interaction between the binder and porous metal oxide, eliminating agglomeration while maintaining good adhesion. The modification creates a compatible interface that mediates the relationship between these two components.
Solution Approach 2:
The patent changes the surface properties of the metal oxide by applying surface modification treatment. This alters the surface parameters (such as surface charge, hydrophobicity, or chemical composition) of the metal oxide, making it compatible with the binder and preventing agglomeration. The parameter change transforms the metal oxide from a material that causes agglomeration to one that maintains good adhesion.
2Quantity of substance
If metal oxide is added to the positive electrode to absorb lithium polysulfide, then the discharge capacity is improved, but agglomeration phenomenon occurs with the binder, decreasing manufacturing processability
Solution Approach 1:
The surface-modified metal oxide acts as an intermediary that maintains separation between the binder and porous metal oxide particles during electrode manufacturing. This prevents agglomeration that would otherwise occur, ensuring uniform distribution of the metal oxide throughout the electrode matrix and maintaining good manufacturing processability while preserving the polysulfide absorption capacity.
Solution Approach 2:
The surface modification creates local quality differences in the metal oxide particles. The modified surface regions have different properties from the bulk material, creating zones that are compatible with the binder. This local quality change allows the metal oxide to maintain its polysulfide absorption function while having a binder-compatible surface that prevents agglomeration during manufacturing.
3Reliability
If coating layer is formed on positive electrode particles to prevent polysulfide dissolution, then the reversible capacity is improved, but the adhesion force with current collector decreases
Solution Approach 1:
The surface-modified metal oxide particles act as intermediary elements embedded in the coating layer structure. They provide anchoring points that maintain strong adhesion to the current collector while the outer surface prevents polysulfide dissolution. The modified surface properties ensure good interfacial bonding without compromising the protective function.
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 approach enhances the adhesion force between the positive electrode active material layer and the current collector, improving manufacturing processability and storage properties while maintaining the discharging capacity and lifetime of the lithium secondary battery.
Implementation Method 1
iron oxyhydroxynitrate with hydrogen phosphate ions adsorbed on its surface
Implementation Method 2
hydrogen phosphate ions adsorbed on its surface as a positive electrode additive, which repels the carboxylate functional group of the binder
Data Source
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AI summary
The present invention relates to an iron oxyhydroxynitrate with hydrogen phosphate ions adsorbed on its surface, a method for preparing the same, a positive electrode for a lithium secondary battery comprising the iron oxyhydroxynitrate with hydrogen phosphate ions adsorbed on its surface as a positive electrode additive, and a lithium secondary battery comprising the same.