High-Nickel Cathode Coating Using Lithium By-Products
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Solution Overview
Problem
High-nickel positive electrode active materials in lithium secondary batteries face challenges with reduced structural and chemical stability, increased side reactions with electrolytes, and rapid thermal instability due to high nickel content, leading to reduced battery lifetime and capacity.
Innovation Solution
A high-nickel lithium composite transition metal oxide with a coating layer formed by reacting lithium by-products with polymers like polyacrylamide or polyimide, enhancing surface stability and thermal resistance without a washing process to remove lithium by-products, thereby improving battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nickel content is increased to achieve high capacity, then battery capacity is improved, but structural stability and chemical stability are reduced
Solution Approach 1:
The patent uses a composite coating structure consisting of an inner layer (alumina, aluminum hydroxide, or aluminum carbonate) and an outer layer (silica or magnesium oxide). This multi-layer composite coating provides both structural support and chemical stability, allowing the high-nickel positive electrode active material to maintain its capacity while achieving the required stability.
Solution Approach 2:
The coating is applied specifically to the surface of the positive electrode active material particles, creating a localized protective layer. This allows the bulk material to maintain its high-nickel composition for capacity while the surface gains the stability properties needed for chemical and structural integrity.
2Quantity of substance
If nickel content is increased to achieve high capacity, then battery capacity is improved, but side reactions with electrolyte solution increase
Solution Approach 1:
The patent introduces a coating layer as an intermediary between the high-nickel positive electrode active material and the electrolyte solution. This coating layer (composed of alumina, aluminum hydroxide, aluminum carbonate, silica, or magnesium oxide) acts as a barrier that prevents direct contact between the reactive nickel-containing material and the electrolyte, thereby suppressing side reactions while allowing the material to deliver its full capacity.
3Quantity of substance
If nickel content is increased to achieve high capacity, then battery capacity is improved, but thermal stability is reduced
Solution Approach 1:
The patent employs a composite coating system with specific materials known for their thermal stability. The inner layer (alumina, aluminum hydroxide, or aluminum carbonate) and outer layer (silica or magnesium oxide) are selected for their high thermal resistance properties, creating a protective barrier that maintains thermal stability even when the underlying high-nickel material is prone to thermal degradation.
4Stability of the object's composition
If conventional coating methods are used, then surface stability is improved, but manufacturing complexity increases due to washing processes
Solution Approach 1:
The patent utilizes lithium by-products naturally present on the surface of the positive electrode active material as a foundation for the coating process. Instead of requiring separate washing steps to remove these by-products, the method incorporates them into the coating structure, allowing the coating to form directly on the as-synthesized material and eliminating additional manufacturing steps.
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 improves structural and chemical stability, suppresses side reactions, and enhances thermal stability, leading to increased battery capacity and extended lifespan while simplifying the production process.
Implementation Method 1
a coating layer including a lithium-polymer compound, which is formed by a reaction of a lithium by-product with a polymer
Implementation Method 2
a side reaction with an electrolyte solution may be suppressed by forming a uniform coating layer
Implementation Method 3
by mixing the lithium composite transition metal oxide with a polymer solution and performing a heat treatment
Data Source
AI summary
The present invention relates to a positive electrode active material for a secondary battery which includes a lithium composite transition metal oxide including nickel (Ni), cobalt (Co), and manganese (Mn), wherein the lithium composite transition metal oxide includes 60 mol% or more of the nickel (Ni) among metals excluding lithium, and a coating layer is formed on surfaces of particles of the lithium composite transition metal oxide, wherein the coating layer includes a lithium-polymer compound which is formed by a reaction of a lithium by-product with a polymer.