Nickel-Rich Cathode Surface Washing for Low-Residual Lithium
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Solution Overview
Problem
Lithium nickel-based oxide cathode active materials for lithium secondary batteries suffer from low cycle-life characteristics, high gas generation, and stability issues due to excessive residual lithium, limiting their long-term use and performance.
Innovation Solution
A cathode active material comprising a lithium metal compound, such as lithium nickel-based oxide, with a specific surface area of 0.5 to 2.0 m2/g and pH of 11.5 to 12.1, where a lithium compound with 0.25 parts by weight or less is disposed on its surface, prepared using ammonia water washing to minimize residual lithium, enhancing electrochemical properties and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium nickel-based oxide with high nickel content is used to achieve high capacity, then capacity is improved, but cycle-life characteristics and stability deteriorate due to large residual lithium on surface
Solution Approach 1:
The patent extracts and removes excess residual lithium from the surface of lithium nickel-based oxide particles through washing with ammonia water. This selective removal of harmful surface lithium while preserving the bulk high-capacity material resolves the contradiction between high capacity and good cycle-life characteristics
Solution Approach 2:
The patent changes the chemical environment parameters by using ammonia water washing to adjust surface composition and pH (controlling pH between 11.5-12.1). This parameter change removes residual lithium and creates a stable surface layer that maintains high capacity while improving cycle-life characteristics
2Quantity of substance
If lithium nickel-based oxide with high nickel content is used to achieve high capacity, then capacity is improved, but stability deteriorates due to large residual lithium on surface
Solution Approach 1:
The patent extracts and removes excess residual lithium from the surface of lithium nickel-based oxide particles through washing with ammonia water. This selective removal of harmful surface lithium while preserving the bulk high-capacity material resolves the contradiction between high capacity and good stability
Solution Approach 2:
The patent changes the chemical environment parameters by using ammonia water washing to adjust surface composition and pH (controlling pH between 11.5-12.1). This parameter change removes residual lithium and creates a stable surface layer that maintains high capacity while improving stability
3Quantity of substance
If residual lithium is not removed to maintain high capacity material composition, then capacity is maintained, but gas generation increases and stability decreases
Solution Approach 1:
The patent extracts and removes excess residual lithium from the surface of lithium nickel-based oxide particles through washing with ammonia water. This selective removal of harmful surface lithium while preserving the bulk high-capacity material resolves the contradiction between high capacity and reduced gas generation
Solution Approach 2:
The patent changes the chemical environment parameters by using ammonia water washing to adjust surface composition and pH (controlling pH between 11.5-12.1). This parameter change removes residual lithium and creates a stable surface layer that maintains high capacity while reducing gas generation
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 solution results in lithium secondary batteries with improved high-capacity, cycle-life, and rate capabilities, reduced gas generation, and enhanced stability, maintaining performance over time.
Implementation Method 1
washing a first active material with ammonia water to obtain a second active material
Implementation Method 2
a cathode including a cathode active material capable of intercalating/deintercalating lithium
Data Source
AI summary
Provided are a cathode active material for a lithium secondary battery, a method for preparing the same, and a lithium secondary battery comprising the same. The cathode active material for a lithium secondary battery comprises: a lithium metal compound; and a lithium compound disposed on the surface of the lithium metal compound, wherein the content of lithium contained in the lithium compound is 0.25 parts by weight or less with respect to 100 parts by weight of the lithium metal compound, wherein the specific surface area of the lithium compound is between 0.5 m2/g and 2.0 m2/g, and the pH of the lithium compound is between 11.5 and 12.3.