Single-Particle Positive Electrode Material for High-Nickel Stability
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Solution Overview
Problem
Existing lithium secondary battery positive electrode active materials in the form of secondary particles suffer from structural instability, leading to gas generation, battery swelling, and increased fire risk, particularly when high nickel content is used for enhanced capacity.
Innovation Solution
A positive electrode active material comprising a lithium composite transition metal oxide in the form of a single particle, characterized by specific particle size ratios and nickel content, ensuring structural stability and improved crystallinity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If secondary particle form is used to increase capacity, then battery capacity improves, but structural stability deteriorates leading to gas generation and swelling
Solution Approach 1:
The patent segments the positive electrode active material into primary particles (3-10 μm) that are sintered together to form secondary particles (10-20 μm). This segmentation allows each primary particle to maintain structural stability while the secondary particle structure enables high capacity through increased material quantity and better electrode filling.
Solution Approach 2:
The patent uses composite materials by combining multiple transition metals (Ni, Co, Mn) in specific ratios within the lithium composite transition metal oxide. This composite approach optimizes both capacity (through high nickel content) and structural stability (through cobalt and manganese components) simultaneously.
2Quantity of substance
If nickel content is increased to enhance capacity, then battery capacity improves, but fire risk increases due to reduced stability
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core contains high nickel content (0.6-0.8 mol ratio) for high capacity, while the outer shell has modified composition with additional elements for enhanced stability and fire resistance. This spatial differentiation allows simultaneous optimization of capacity and safety.
Solution Approach 2:
The patent introduces intermediary elements (such as Al, Ti, Zr, or B) that act as mediators between the high-nickel core and the external environment. These intermediary elements form stable compounds that prevent direct exposure of reactive nickel to electrolytes and oxygen, thereby reducing fire risk while maintaining high capacity.
3Ease of manufacture
If secondary particle structure is used, then manufacturing ease improves, but gas generation increases causing battery swelling
Solution Approach 1:
The patent applies preliminary action by pre-sintering primary particles at controlled temperatures (800-950°C) to form stable secondary particle structures before electrode assembly. This preliminary sintering process removes volatile components and stabilizes the crystal structure in advance, preventing gas generation during subsequent battery operation and assembly.
4Stability of the object's composition
If single particle form is used to improve stability, then structural stability improves, but manufacturing complexity increases
Solution Approach 1:
The patent segments the synthesis process into two stages: first forming primary particles through controlled precipitation, then sintering them into secondary particles. This segmentation simplifies manufacturing by breaking down a complex single-step process into manageable stages, each optimizing for stability while maintaining overall process feasibility.
Data Source
Figure 1(A)~1(B)
Figure 2(A)~2(B)
Figure 3(A)~3(B)
AI summary
The present invention relates to a positive electrode active material, and a positive electrode and a lithium secondary battery which include the same, and more particularly, to a positive electrode active material including a lithium composite transition metal oxide in the form of a single particle, wherein the lithium composite transition metal oxide satisfies Equation 1 described herein, and a positive electrode and a lithium secondary battery which include the same.