Dual-Coated Cathode Active Material for Stable Lithium Batteries
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Solution Overview
Problem
Lithium composite oxides used in secondary batteries suffer from surface reactions that degrade performance due to exposure to the atmosphere or contact with electrolyte, leading to the formation of impurities and reduced stability.
Innovation Solution
A cathode active material is developed with a first coating part containing aluminum and a second coating part containing boron, sequentially formed on the surface of a lithium composite oxide, which stabilizes the surface structure and reduces reaction areas with the electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium composite oxide is exposed to atmosphere or contacts with electrolyte, then battery capacity is improved through active material exposure, but side reactions occur forming lithium and nickel by-products that deteriorate life-span and operational stability
Solution Approach 1:
An aluminum-containing coating layer is introduced as an intermediary between the lithium composite oxide and the electrolyte/atmosphere. This coating layer acts as a protective barrier that prevents direct contact and side reactions, while still allowing lithium ion transport. The aluminum coating specifically suppresses the formation of lithium by-products (such as LiOH and Li2CO3) and nickel by-products by blocking the reaction pathways between the active material and external environment.
2Quantity of substance
If high nickel content is used in lithium composite oxide, then battery capacity and output are improved, but large amounts of lithium impurities form on surface causing decrease in battery performance
Solution Approach 1:
The harmful lithium impurities (LiOH, Li2CO3) and nickel by-products are prevented from forming on the surface by extracting them through the aluminum-containing coating layer. The coating acts as a barrier that stops the formation process at the interface, effectively removing the harmful effect of high nickel content materials before the impurities can accumulate and degrade battery performance.
3Object-generated harmful factors
If lithium impurities are washed with water, then lithium impurities are removed from surface, but specific surface area increases activating side reactions with electrolyte and deteriorating surface structure stability
Solution Approach 1:
The aluminum-containing coating layer is applied in advance before the battery is assembled and before any washing processes occur. This preliminary protective action prevents the need for subsequent washing that would increase surface area and activate side reactions. The coating is already in place to protect the surface structure stability while allowing controlled lithium ion transport.
4Reliability
If coating layers are formed on lithium composite oxide surface, then stability and resistance to side reactions are improved, but manufacturing process complexity increases
Solution Approach 1:
The coating process utilizes controlled parameter changes including aluminum source concentration (0.1-10 wt%), coating temperature (20-100°C), and drying temperature (50-200°C) to optimize the coating formation. By carefully controlling these parameters, the process achieves effective protection against side reactions while maintaining manufacturing feasibility and avoiding excessive complexity.
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 proposed coating structure enhances the life-span and high-temperature stability of the lithium secondary battery by preventing side reactions and maintaining structural integrity.
Implementation Method 1
a first coating part formed on a surface of the lithium composite oxide and containing aluminum; and a second coating part formed on the first coating part and containing boron
Data Source
AI summary
A cathode active material for a lithium secondary battery of embodiments of the present invention includes a lithium composite oxide, a first coating part formed on a surface of the lithium composite oxide and containing aluminum, and a second coating part formed on the first coating part and containing boron. Thereby, stability and electrical characteristics of the secondary battery may be improved.