Metal-Phosphorous-Oxynitride Coating for Lithium Battery Stability
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Solution Overview
Problem
Current positive electrode active materials for lithium secondary batteries face challenges in stability and lifetime under high voltage and high temperature conditions, with existing coating methods being complex, costly, and inefficient, limiting their application in large capacity batteries like electric vehicles.
Innovation Solution
A method is developed to form a metal-phosphorous-oxynitride protective layer on positive electrode active materials using a solution process with a coating composition containing a phosphorous-nitrogen bond precursor, which is heat-treated to create a stable and conductive layer, enhancing the material's performance and longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective layer is formed on positive electrode active material to improve stability and lifetime, then reliability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent changes the chemical composition parameters of the coating layer by incorporating phosphorous and nitrogen elements in specific ratios (P: 0.1-5 wt%, N: 0.1-5 wt%). This compositional parameter optimization provides both protective function and ion conductivity without requiring complex multi-layer structures, thus improving reliability while controlling device complexity
Solution Approach 2:
The patent creates a composite coating material combining metal-phosphorous-oxynitride with conductive components. This composite structure achieves multiple functions (protection, conductivity, ion transport) in a single layer, eliminating the need for multiple separate coating layers and reducing overall device complexity
2Reliability
If conventional coating methods are used to form protective layer, then reliability is improved, but manufacturing cost and process complexity increase
Solution Approach 1:
The patent combines the protective coating formation with the existing electrode manufacturing process by applying the coating solution directly to the positive electrode active material before or during electrode assembly. This merging of processes eliminates separate coating equipment and steps, reducing manufacturing cost and complexity while ensuring reliable protective coverage
Solution Approach 2:
The patent uses a solution-based coating method where the metal-phosphorous-oxynitride is delivered as a soluble precursor that decomposes during heat treatment. This intermediary solution form enables simple application methods (dip-coating, spray-coating, or inkjet printing) without requiring complex vacuum deposition equipment, reducing manufacturing cost while achieving reliable protective layers
3Use of energy by moving object
If high voltage operation is implemented to increase capacity, then energy density is improved, but stability and lifetime deteriorate due to cobalt dissolution and structural changes
Solution Approach 1:
The patent applies a protective coating layer containing phosphorous and nitrogen elements before the electrode undergoes high voltage operation. This pre-applied protective layer prevents cobalt dissolution and structural changes by forming a stable interface barrier, countering the harmful effects of high voltage operation before they can occur, thus enabling high energy density operation while maintaining reliability
4Reliability
If coating layer is formed to prevent cobalt dissolution and structural changes, then reliability is improved, but ion conductivity may be reduced
Solution Approach 1:
The patent optimizes the chemical composition parameters of the coating layer by incorporating nitrogen elements and controlling phosphorous content (P: 0.1-5 wt%, N: 0.1-5 wt%). This compositional parameter adjustment creates a coating that is chemically stable against cobalt dissolution yet maintains adequate ion conductivity through its specific chemical structure and porosity characteristics
Solution Approach 2:
The patent creates a composite coating material that combines protective metal-phosphorous-oxynitride with conductive components. This composite structure provides both the protective function (preventing cobalt dissolution and structural changes) and maintains ion conductivity pathways, achieving a balance between reliability and power that neither component could achieve alone
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 method allows for the simple and cost-effective formation of a protective layer that improves the capacity and lifetime of lithium secondary batteries, providing enhanced stability and ion conductivity, making them suitable for high-performance applications.
Implementation Method 1
heat-treated to create a stable and conductive layer
Implementation Method 2
forming a metal-phosphorous-oxynitride protective layer on the positive electrode active material by heat treating the positive electrode active material having the precursor layer formed thereon
Data Source
AI summary
A method for preparing a positive electrode active material, a positive electrode active material prepared using the same, and a lithium secondary battery, and in particular, to a method for preparing a positive electrode active material comprising the steps of (a) preparing a coating composition including a precursor of metal-phosphorous-oxynitride; (b) forming a precursor layer on a positive electrode active material with the coating composition of (a) using a solution process; and (c) forming a metal-phosphorous-oxynitride protective layer on the positive electrode active material by heat treating the positive electrode active material having the precursor layer formed thereon. The method for preparing a positive electrode active material uses a solution process, which is advantageous in terms of simplifying the whole process and reducing costs, and high capacity, high stabilization and long lifetime are obtained as well by the formed protective layer having excellent properties.