Composite Coating Layer for High-Ni Cathode Particle Stability
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Solution Overview
Problem
Lithium secondary batteries face challenges with particle separation during charging and discharging due to the structural characteristics of secondary particles, leading to deteriorated battery performance and limited lifespan, especially with high Ni content cathode active materials, which also suffer from oxygen desorption issues during calcination, resulting in increased resistance and side reactions.
Innovation Solution
A cathode active material with a composite coating layer comprising a crystalline and amorphous coating part applied to a one-body core, where the crystalline coating part improves resistance and lifespan characteristics by rearranging the surface structure and reducing cation mixing, while the amorphous coating part suppresses electrolyte side reactions and enhances structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a one-body cathode active material structure is used to prevent particle separation, then particle stability during charging and discharging is improved, but oxygen desorption during calcination occurs leading to increased resistance and deteriorated lifespan characteristics
Solution Approach 1:
A coating layer comprising a crystalline coating part and an amorphous coating part is applied to the one-body cathode active material surface. The coating layer acts as an intermediary that suppresses oxygen desorption during calcination while maintaining the one-body structure's particle stability, thereby resolving the contradiction between structural integrity and oxygen loss prevention
2Quantity of substance
If high Ni content is increased to improve battery capacity, then battery requirements are better met, but oxygen desorption during calcination becomes more serious leading to increased resistance
Solution Approach 1:
The coating layer serves as a protective intermediary on high-Ni cathode active materials, suppressing oxygen desorption during calcination that would otherwise occur more severely with increased Ni content, thereby enabling high-capacity materials to be processed without excessive resistance increase
3Ease of manufacture
If conventional coating materials are used, then coating application is simple, but the coating exists in amorphous form failing to provide desired lifespan and high-temperature characteristics
Solution Approach 1:
The coating layer is designed as a composite structure comprising both crystalline and amorphous coating parts. This composite approach combines the structural stability and high-temperature characteristics of crystalline regions with the coating simplicity and surface coverage of amorphous regions, achieving both ease of manufacture and improved reliability
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 composite coating layer prevents particle separation, improves initial capacity and lifespan, reduces lithium by-products, and enhances high-temperature characteristics by providing structural stability and suppressing side reactions, thus addressing the limitations of conventional cathode active materials.
Implementation Method 1
a crystalline coating part and an amorphous coating part, formed on the one-body core
Implementation Method 2
rearranging the surface structure and reducing cation mixing
Implementation Method 3
the amorphous coating part suppresses electrolyte side reactions and enhances structural stability
Data Source
AI summary
Disclosed is a cathode active material including a one-body core containing lithium transition metal oxide, and a composite coating layer located on the one-body core, wherein the composite coating layer includes a crystalline coating part and an amorphous coating part.