Stripe-Coated Lithium Battery Cathode Material
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Solution Overview
Problem
Existing positive electrode materials with large primary particles form a rocksalt structure on the surface, leading to deteriorated electrochemical performance in lithium secondary batteries.
Innovation Solution
A positive electrode active material with a modified surface structure featuring a coating layer in the form of stripe-shaped patterns on metal oxide particles, including specific dimensions and compositions, is developed to enhance electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If the size of primary particles is increased using a sintering agent or flux, then the plate density of the electrode is improved, but a rocksalt structure is produced on the surface portion of the particles which deteriorates the electrochemical performance
Solution Approach 1:
The invention applies a coating layer with specific local composition (containing Al, Co, and Ni in controlled ratios) only on the surface portion of the positive electrode active material particles. This local modification suppresses rocksalt structure formation at the surface while maintaining the desired particle size and plate density in the bulk, thereby resolving the contradiction between improved plate density and maintained electrochemical performance.
Solution Approach 2:
The invention creates a composite structure where a coating layer with specific elemental composition (Al, Co, Ni) is formed on the surface of the positive electrode active material particles. This composite structure combines the benefits of increased particle size for high plate density with surface protection against rocksalt formation, maintaining excellent electrochemical performance.
2Volume of stationary object
If a secondary particle form composed of agglomerated primary particles is used to increase plate density, then the electrode plate density is improved, but the large powder specific surface area causes high possibility of gassing and deterioration of life characteristics
Solution Approach 1:
The invention applies a protective coating layer specifically on the surface of individual primary particles before they agglomerate into secondary particles. This local surface modification reduces the reactive surface area that would otherwise cause gassing and life deterioration, while still allowing the secondary particles to maintain high plate density through controlled agglomeration.
Solution Approach 2:
The coating layer is formed on the primary particles before the agglomeration process that creates secondary particles. This preliminary action protects the particle surfaces from electrolyte contact and gassing issues before the particles are assembled into high-density secondary particle structures, thereby preventing life characteristic deterioration while achieving high plate density.
Data Source
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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.