Striped Coating on Single-Particle Cathodes for Low-Gassing Li-Ion Cells
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Solution Overview
Problem
Existing positive electrode materials with high nickel content suffer from high powder specific surface area, leading to increased contact with electrolytic solution, causing gassing and deterioration of life characteristics, and surface modifications like sintering agents result in a rocksalt structure that deteriorates electrochemical performance.
Innovation Solution
A positive electrode active material with a metal oxide in the form of a single particle and a coating layer featuring stripe-shaped protrusions on its surface, optimized in dimensions and composition to enhance electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the size of primary particles is increased using a sintering agent or flux, then the powder specific surface area is reduced and contact with electrolytic solution is decreased, but a rocksalt structure is produced on the surface portion of the particles which deteriorates electrochemical performance
Solution Approach 1:
The patent applies parameter changes by precisely controlling sintering temperature (700-900°C) and time (5-20 hours) to increase primary particle size while preventing rocksalt structure formation. This optimized parameter range allows achieving reduced specific surface area (0.03-0.15 m²/g) without the harmful side effects of conventional sintering methods.
Solution Approach 2:
The patent creates a composite structure consisting of large primary particles (2-5 μm) formed by sintering multiple smaller particles, where the composite maintains the beneficial properties of fine particles (high capacity) while achieving the advantages of large particles (low specific surface area). The composite structure prevents rocksalt phase formation while reducing electrolyte contact.
2Quantity of substance
If a high nickel-based NCM positive electrode material is used to meet high capacity and energy density demands, then energy density is improved, but gassing and deterioration of life characteristics occur due to high powder specific surface area
Solution Approach 1:
The patent changes the particle size parameter to 2-5 μm and controls specific surface area to 0.03-0.15 m²/g, which reduces gassing reactions and improves lifespan while maintaining high nickel content (Ni > 0.5) for high energy density. This parameter optimization resolves the contradiction between capacity and longevity.
3Volume of stationary object
If a secondary particle form composed of agglomeration of primary particles is used to increase plate density, then electrode density is improved, but powder specific surface area increases causing high possibility of gassing
Solution Approach 1:
The patent segments the electrode material into distinct primary particles (2-5 μm) that are sintered together, rather than forming secondary particle agglomerates. This segmentation maintains low specific surface area while achieving high electrode density through close packing of primary particles, preventing gassing issues associated with fine particle agglomerates.
Data Source
AI summary
The present exemplary embodiments relate to a positive electrode active material for a lithium secondary battery, and a lithium secondary battery including the same. The positive electrode active material for a lithium secondary battery according to an exemplary embodiment includes: a metal oxide in the form of a single particle; and a coating layer positioned on the surface of the metal oxide, wherein the coating layer includes a plurality of stripe shapes including a protruding portion based on a cross section in a length direction.