LiNiO2 Surface Treatment for Water-Based Binder Compatibility
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Solution Overview
Problem
Lithium secondary batteries with water-based binders face issues of decreased battery capacity and deteriorated large current discharge properties when using LiNiO2 positive electrode active materials with high specific surface areas, due to the high reactivity of these materials with water.
Innovation Solution
An electrode mixture comprising a lithium mixed metal oxide represented by formula Liz(Ni1-x-yMnxMy)O2, an electrically conductive material, and a water-dispersible polymeric binder, where the binder contains an aqueous emulsion or dispersion, and a thickener, applied onto a current collector to form a nonaqueous electrolyte secondary battery with improved capacity and discharge properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If water-based binders are used to reduce production costs, then manufacturing cost decreases, but battery capacity and large current discharge properties deteriorate due to high reactivity between LiNiO2 and water
Solution Approach 1:
The patent introduces a surface treatment layer as an intermediary between the LiNiO2 active material and the water-based binder. This treatment layer (containing compounds like Li2SiO3, Li3PO4, LiF, or their mixtures) acts as a protective barrier that prevents direct contact and reaction between water in the binder and the reactive LiNiO2 surface, thereby maintaining battery capacity while enabling cost-effective water-based binder usage
Solution Approach 2:
The patent modifies the surface properties of LiNiO2 particles through surface treatment with specific compounds (silicates, phosphates, fluorides). This changes the surface chemistry parameters to reduce water reactivity while maintaining electrochemical performance, allowing the use of water-based binders without sacrificing battery capacity
2Ease of manufacture
If water-based binders are used, then production cost decreases, but large current discharge properties deteriorate
Solution Approach 1:
The surface treatment layer serves as a mediator that facilitates efficient lithium ion transport while blocking harmful water reactions. Treatments with Li2SiO3, Li3PO4, or LiF create conductive pathways that maintain electron and ion transport efficiency, preserving large current discharge properties despite using water-based binders
Solution Approach 2:
The surface treatment modifies electrical and ionic conductivity parameters of the active material surface. By controlling surface composition and structure through treatment with specific compounds, the patent maintains high electronic conductivity and ionic transport efficiency necessary for fast discharge rates
3Reliability
If small particle size LiNiO2 is used to enhance battery capacity, then battery capacity increases, but reactivity with water increases causing performance deterioration
Solution Approach 1:
The surface treatment layer acts as a protective intermediary coating on small particle size LiNiO2. This layer (comprising Li2SiO3, Li3PO4, LiF, or mixtures) provides physical and chemical protection to the high-surface-area particles, preventing water from accessing and reacting with the reactive LiNiO2 surface while allowing lithium ion diffusion necessary for high capacity
Solution Approach 2:
The surface treatment changes the surface area to volume ratio effects by adding a protective shell. While small particles inherently have high reactivity due to large surface area, the treatment layer creates a controlled interface that reduces water reactivity while maintaining the beneficial high capacity characteristics of fine particles
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 solution enhances battery capacity and maintains excellent large current discharge properties while using a water-based binder, reducing production costs and environmental impact by stabilizing the reactivity of LiNiO2 with water, thus achieving a nonaqueous electrolyte secondary battery with sufficient initial discharge capacity.
Implementation Method 1
it has been found that when a surface of a positive electrode active material is treated with a specific compound, it is possible to provide an electrode mixture and an electrode, which lead to a nonaqueous electrolyte secondary battery having a sufficient battery capacity
Data Source
AI summary
The present invention provides an electrode mixture, an electrode and a nonaqueous electrolyte secondary battery. The electrode mixture includes a lithium mixed metal oxide represented by formula (1):Liz(Ni1-x-yMnxMy)O2 (1),an electrically conductive material, and a water-dispersible polymeric binder, wherein x is 0.30 or more and less than 1, y is 0 or more and less than 1, x+y is 0.30 or more and less than 1, z is 0.5 or more and 1.5 or less, and M represents one or more members selected from the group consisting of Co, Al, Ti, Mg and Fe.