Single-Particle Cathode Coating With Spinel-Layered Phase Gradient
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Solution Overview
Problem
High-nickel-based positive electrode active materials in lithium secondary batteries face issues with capacity reduction and increased resistance due to high nickel content, and conventional cobalt coatings lead to slurry viscosity increases and gas generation.
Innovation Solution
A positive electrode active material with a lithium composite transition metal oxide in a single particle form, coated with a cobalt layer having a phase gradient from spinel to layered structure, is developed, along with a method involving a heat treatment process to form this gradient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a high-nickel-based positive electrode active material is used to increase capacity, then energy density is improved, but resistance increases and capacity reduction occurs during battery cycles
Solution Approach 1:
The patent applies composite materials by coating the high-nickel-based positive electrode active material with a dual-layer structure consisting of a spinel structure coating layer and a layered structure coating layer. This composite structure combines the high capacity benefits of high-nickel materials with the protective and conductive properties of the coating layers, resolving the contradiction between energy density and resistance stability.
Solution Approach 2:
The patent implements local quality by creating a phase gradient within the coating portion where the spinel structure predominates at the outer surface and the layered structure predominates at the inner surface adjacent to the active material. This spatial variation in coating properties optimizes both surface protection and interfacial compatibility, addressing the resistance and capacity reduction issues.
2Productivity
If a conventional cobalt coating layer with layered structure is formed on the positive electrode active material, then capacity characteristics are improved, but slurry viscosity increases and initial resistance increases
Solution Approach 1:
The patent applies local quality by creating a phase gradient within the coating portion where the spinel structure predominates at the outer surface and the layered structure predominates at the inner surface. This spatial variation in coating properties optimizes both surface protection and interfacial compatibility, addressing the resistance and capacity reduction issues.
Solution Approach 2:
The patent applies composite materials by coating the high-nickel-based positive electrode active material with a dual-layer structure consisting of a spinel structure coating layer and a layered structure coating layer. This composite structure combines the high capacity benefits of high-nickel materials with the protective and conductive properties of the coating layers, resolving the contradiction between energy density and resistance stability.
3Productivity
If a conventional cobalt coating layer with layered structure is formed on the positive electrode active material, then capacity characteristics are improved, but gas generation amount increases
Solution Approach 1:
The patent applies composite materials by coating the high-nickel-based positive electrode active material with a dual-layer structure consisting of a spinel structure coating layer and a layered structure coating layer. This composite structure combines the high capacity benefits of high-nickel materials with the protective and conductive properties of the coating layers, resolving the contradiction between energy density and resistance stability.
Solution Approach 2:
The patent applies preliminary anti-action by forming the spinel structure coating layer at the outer surface of the coating portion, which acts as a protective barrier that prevents direct contact between the electrolyte and the layered structure coating layer, thereby preventing side reactions that would otherwise generate gas.
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 phase gradient coating improves electrical conductivity, reduces initial resistance, and minimizes gas generation, enhancing the battery's storage characteristics and energy density.
Implementation Method 1
the coating portion containing cobalt has a phase gradient from a spinel structure to a layered structure in a central direction from a surface of the positive electrode active material
Implementation Method 2
a method involving a heat treatment process to form this gradient
Implementation Method 3
a side reaction with an electrolyte solution may be prevented to suppress a gas generation amount
Data Source
AI summary
The present invention relates to a positive electrode active material, wherein it relates to a positive electrode active material including a lithium composite transition metal oxide in a form of a single particle; and a coating portion containing cobalt which is formed on the lithium composite transition metal oxide in the form of a single particle, wherein the coating portion containing cobalt has a phase gradient from a spinel structure to a layered structure in a central direction from a surface of the positive electrode active material, a preparation method thereof, and a lithium secondary battery including the positive electrode active material.