Nickel-Rich Cathode Material With Manganese Shell for Battery Stability
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Solution Overview
Problem
Lithium composite transition metal oxides with high nickel content face challenges in achieving long-term lifetime and thermal stability in lithium secondary batteries, limiting their capacity and efficiency.
Innovation Solution
A positive electrode active material with a core portion of lithium transition metal oxide having 80 mol% nickel and a layer-structured shell portion with high manganese content, where the shell thickness is optimized relative to the average particle diameter, is developed. This material is prepared through a method involving the precipitation of nickel, cobalt, and manganese in different regions, followed by mixing with lithium and sintering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high nickel content lithium composite transition metal oxide is used to improve capacity characteristics, then the energy density and capacity of the battery are improved, but the long-term lifetime and thermal stability deteriorate
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the core portion contains high nickel content (80 mol% or more) for high capacity, while the shell portion contains high manganese content (30 mol% or more) for stability. This spatial differentiation of composition allows each region to perform its specific function: the nickel-rich core provides high capacity while the manganese-rich shell provides protective stability and thermal resistance.
Solution Approach 2:
The patent uses composite materials by combining nickel-rich lithium transition metal oxide core with manganese-rich shell to form a composite structure. This composite approach allows the material to simultaneously exhibit high capacity characteristics from the nickel component and improved stability from the manganese component, resolving the contradiction between capacity and reliability.
2Ease of manufacture
If conventional co-precipitation method is used to prepare uniform composition lithium composite transition metal oxide, then the manufacturing process is simple, but the life characteristics and thermal stability are insufficient
Solution Approach 1:
The patent applies segmentation by dividing the precipitation process into two sequential stages: first precipitating nickel and cobalt to form the core, then precipitating manganese to form the shell. This segmented approach creates the desired core-shell structure with differentiated composition, improving life characteristics and thermal stability while maintaining a relatively simple manufacturing process based on conventional co-precipitation technology.
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 optimized positive electrode active material enhances initial charge and discharge efficiency, long-term life characteristics, and thermal stability of lithium secondary batteries by concentrating manganese on the surface for protective layer formation.
Implementation Method 1
a layer-structured shell portion formed on the core portion and including a lithium transition metal oxide wherein a molar ratio of manganese (Mn) in the total transition metals is 30 mol % or more
Implementation Method 2
the precipitation of nickel, cobalt, and manganese in different regions, followed by mixing with lithium and sintering
Implementation Method 3
mixing with lithium and sintering
Data Source
AI summary
Provided is a positive electrode active material capable of achieving a lithium secondary battery having excellent initial charge and discharge efficiency, life characteristics, and thermal stability and a preparation method thereof, wherein the positive electrode active material of the present invention includes a core portion including a lithium transition metal oxide wherein a mole ratio of nickel (Ni) in total transition metals is 80 mol % or more, and a layer-structured shell portion formed on the core portion and including a lithium transition metal oxide in which a molar ratio of manganese (Mn) in the total transition metals is 30 mol % or more, and satisfies Equation 1:0.005≤Thickness of the shell portion(μm)Average particle diameter(D50) of the positive electrode active material(μm)≤0.15.[Equation 1]