High-Nickel Cathode Material with Core-Shell Composition Stability
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Solution Overview
Problem
Conventional NCM-based and NCA-based lithium composite transition metal oxides have insufficient capacity characteristics and limited application due to difficulties in controlling sintering conditions and crystal size, leading to reduced structural and chemical stability, which affects battery capacity and life characteristics.
Innovation Solution
A positive electrode active material with a center portion and surface portion having different compositions, specifically a high-Ni content with nickel at 60 mol% or more, and controlled ratios of nickel to other transition metals, including a core-shell or concentration gradient structure to improve stability and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nickel content is increased to 60 mol% or more in NCM-based/NCA-based lithium oxides, then battery capacity and energy density are improved, but sintering conditions become difficult to control and crystal structure stability deteriorates
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the surface portion has different composition characteristics from the center portion. The surface portion contains modified transition metal ratios to enhance stability, while the center portion maintains high nickel content for capacity. This spatial differentiation of material properties resolves the contradiction between high nickel content and structural stability.
Solution Approach 2:
The patent uses composite materials by combining multiple transition metals (nickel, cobalt, manganese, aluminum) in specific ratios within a lithium composite oxide structure. The composite nature allows the material to simultaneously achieve high capacity from nickel and structural stability from cobalt, manganese, and aluminum, resolving the trade-off between capacity and stability.
2Quantity of substance
If nickel content is increased to 60 mol% or more, then battery capacity characteristics are improved, but sintering temperature and atmosphere control become difficult
Solution Approach 1:
The patent applies parameter changes by optimizing the ratios of transition metals within the high-nickel composition. By adjusting cobalt, manganese, and aluminum content alongside nickel, the material achieves stable sintering behavior at 60 mol% or more nickel content, while maintaining desired oxidation states and crystal structure during the sintering process.
3Quantity of substance
If nickel content is increased to 60 mol% or more, then battery capacity is improved, but chemical stability is reduced
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the surface portion has different composition characteristics from the center portion. The surface portion contains modified transition metal ratios to enhance stability, while the center portion maintains high nickel content for capacity. This spatial differentiation of material properties resolves the contradiction between high nickel content and structural stability.
Solution Approach 2:
The patent uses composite materials by combining multiple transition metals (nickel, cobalt, manganese, aluminum) in specific ratios within a lithium composite oxide structure. The composite nature allows the material to simultaneously achieve high capacity from nickel and structural stability from cobalt, manganese, and aluminum, resolving the trade-off between capacity and stability.
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 provides a positive electrode active material with enhanced capacity, stability, and output characteristics, while maintaining high nickel content, thereby improving battery performance and extending its lifespan.
Implementation Method 1
electrical energy is produced by oxidation and reduction reactions when the lithium ions are intercalated/deintercalated into/from the positive electrode and the negative electrode
Data Source
AI summary
The present invention provides to a positive electrode active material, which includes a center portion including a first lithium transition metal oxide with an average composition represented by Formula 1, and a surface portion including a second lithium transition metal oxide with an average composition represented by Formula 2, a method of preparing the same, a positive electrode including the positive electrode active material, and a lithium secondary battery having improved charge and discharge efficiency by including the positive electrode. [Formula 1] Li1+a1(Nib1Coc1Mnd1Ale1M1f1)O2 In Formula 1, -0.1≤a1≤0.2, 0.8≤b1<1.0, 0<c1≤0.2, 0<d1≤0.1, 0<e1≤0.05, 0≤f1≤0.05, b1/c1≤25, and b1/d1≥20, and M1 includes at least one selected from the group consisting of Mg, Ti, Zr, Nb, and W. [Formula 2] Li1+a2(Nib2Coc2Mnd2Ale2M1f2)O2 In Formula 2, -0.1≤a2≤0.2, 0.6≤b2≤0.95, 0<c2≤0.2, 0<d2≤0.1, 0<e2≤0.05, 0≤f2≤0.05, b2/c2<13, and b2/d2≥3, and M1 includes at least one selected from the group consisting of Mg, Ti, Zr, Nb, and W.