Cathode Active Material Surface Structuring for Lower Initial Resistance
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Solution Overview
Problem
Existing cathode active materials face challenges in achieving desired initial resistance due to insufficient reaction area on the particle surface, which hinders optimal lithium migration.
Innovation Solution
A cathode active material comprising first particles with a maximum Feret diameter of 1 μm or more and second particles with a maximum Feret diameter of 50 nm or less adhering to the surface at an adhesion rate of 0.24 particles or more per 1 μm², enhancing the reaction area and promoting lithium migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the particle size is increased to reduce surface area, then the initial resistance increases, but the reaction area decreases
Solution Approach 1:
The cathode active material is divided into two distinct particle size populations: first particles with a maximum Feret diameter of 1 μm or more, and second particles with a maximum Feret diameter of 50 nm or less. This segmentation allows each particle type to fulfill different functional roles - the larger first particles provide structural stability while the smaller second particles increase the reaction area and reduce initial resistance through their high surface area to volume ratio
Solution Approach 2:
The patent applies local quality by having the second particles (50 nm or less) specifically adhere to the surface of the first particles (1 μm or more). This creates a heterogeneous surface structure where the fine second particles are concentrated at the surface region, locally enhancing the reaction area without significantly increasing the overall particle size. The adhesion amount of 0.24 particles or more per 1 μm² ensures sufficient surface coverage to reduce initial resistance while maintaining the beneficial properties of the larger first particles
2Area of stationary object
If fine particles are added to increase reaction area, then the initial resistance decreases, but the particle structure complexity increases
Solution Approach 1:
The patent creates a composite particle structure consisting of first particles (1 μm or more) and second particles (50 nm or less) with different size characteristics. This composite structure combines the advantages of both particle types: the larger first particles provide structural integrity and ease of handling, while the smaller second particles contribute high surface area for enhanced reaction. The composite nature allows the system to achieve reduced initial resistance through increased reaction area while maintaining manageable structural complexity through defined particle size ranges and adhesion characteristics
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 configuration reduces initial resistance by increasing the reaction area and improving lithium migration, resulting in improved performance of secondary batteries.
Implementation Method 1
The second particle adheres to a surface of the first particle. An amount of adhesion of the second particle is 0.24 particles or more per 1 μm².
Data Source
AI summary
The cathode active material includes first particles and second particles. The first particle has a maximum Feret diameter of 1 μm or greater. The second particle has a maximum Feret diameter less than or equal to 50 nm. The second particle is attached to the surface of the first particle. The second particles are deposited in an amount of 0.24 or more per 1 μm2.