Core-Shell NCM Cathode Material for Longer Lithium Battery Cycle Life
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries face issues with cycle-life degradation due to high specific surface area and weak particle strength of NCM positive electrode materials, leading to gas generation and poor particle uniformity, which affects energy density and durability.
Innovation Solution
A metal oxide particle with a core-shell structure, where the surface includes an amorphous carbon-lithium film and a rock salt structure, and the core has a layered structure, combined with doping elements like Zr and Al, to enhance particle strength and uniformity, and a manufacturing method involving co-precipitation, sintering, and secondary sintering to achieve specific particle size and surface area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the specific surface area of the powder is large, then the area in contact with the electrolyte solution is wide, but there is a high possibility of gas generation and cycle-life degradation
Solution Approach 1:
The patent applies a thin film coating on the surface of the positive electrode active material particles. This film acts as a protective barrier that reduces direct contact between the high-surface-area powder and the electrolyte solution, thereby preventing gas generation and cycle-life degradation while maintaining the beneficial high surface area for electrochemical reactions.
2Strength
If the size of the primary particle is increased, then the cake strength increases and disintegration becomes difficult, but particle uniformity is deteriorated due to fine powder and coarse powder
Solution Approach 1:
The patent creates a composite structure where primary particles are aggregated into secondary particles with a controlled bimodal size distribution. The composite nature of these aggregated particles provides sufficient mechanical strength to prevent disintegration during rolling, while the controlled aggregation process maintains particle uniformity by preventing excessive fine powder generation.
Solution Approach 2:
The patent segments the particle system into a bimodal distribution with both large and small particles in specific fractions. This segmentation allows the larger particles to provide structural strength and prevent disintegration, while the smaller particles fill interstices and maintain uniformity, resolving the contradiction between strength and uniformity.
3Quantity of substance
If NCM positive electrode material with high Ni content is used, then high-capacity and high energy density are achieved, but cycle-life degradation occurs due to weak particle strength
Solution Approach 1:
The patent applies local quality modification by coating only the surface of the high-Ni NCM particles with a protective thin film. This allows the core material to maintain its high nickel content and associated high energy density, while the surface film locally provides the mechanical strength and chemical stability needed to prevent cycle-life degradation.
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 results in a positive electrode active material with excellent particle uniformity, high strength, and improved cycle-life characteristics, enabling increased energy density and thermal stability in lithium secondary batteries.
Implementation Method 1
the surface portion includes a film in which no peak is observed during XRD measurement. The film contains a compound of amorphous structure. The compound of amorphous structure contains carbon and lithium.
Implementation Method 2
obtaining a metal hydroxide by supplying the metal salt aqueous solution to a co-precipitation reactor
Implementation Method 3
obtaining a lithium metal oxide by mixing the metal hydroxide, a lithium raw material, a doping raw material and a boron compound and then sintering them
Data Source
AI summary
The present exemplary embodiments provide a positive electrode active material, a manufacturing method thereof, and a lithium secondary battery including the same. The positive electrode active material according to an exemplary embodiment is a metal oxide particle including a center and a surface portion positioned on the surface of the center, but the metal oxide particle is composed of a single particle, and the surface portion includes a film in which no peak is observed during XRD measurement.