Cathode Active Material Coating to Limit Residual Lithium
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Solution Overview
Problem
Conventional lithium secondary battery positive electrode active materials face issues with electrochemical characteristics and stability due to the presence of Li impurities on their surface, which are exacerbated by high-Ni types, leading to gelation and swelling, and traditional washing processes to remove these impurities can damage the material.
Innovation Solution
A positive electrode active material is developed with a lithium composite oxide core coated by a layer of specific oxides and optionally a shell layer, which reduces Li impurities without a washing process, enhancing stability and electrochemical performance through controlled surface composition and concentration gradients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a washing process is used to remove Li impurities from the surface of the positive electrode active material, then the content of residual Li impurities is reduced, but the surface of the positive electrode active material is damaged
Solution Approach 1:
The patent extracts and removes Li impurities from the surface of the positive electrode active material through a washing process using deionized water, thereby reducing the content of residual Li impurities while maintaining surface integrity through controlled washing conditions
Solution Approach 2:
The patent controls washing parameters including water temperature, washing time, and water-to-material ratio to optimize the removal of Li impurities while preventing surface damage, achieving a balance between purification and surface preservation
2Quantity of substance
If the content of Ni in the positive electrode active material is increased to improve capacity characteristics, then the capacity is improved, but the content of Li impurities on the surface increases proportionally
Solution Approach 1:
The patent converts the harmful effect of increased Li impurities (which naturally occur with higher Ni content) into a manageable parameter by implementing a targeted washing process that specifically removes Li impurities while preserving the high-capacity Ni-rich material structure
Solution Approach 2:
The patent adjusts the washing process parameters based on the Ni content level, optimizing water temperature, washing time, and water-to-material ratio to effectively remove Li impurities from high-Ni materials without compromising their capacity characteristics
3Reliability
If a washing process is implemented to reduce residual lithium, then the electrochemical characteristics are improved, but the manufacturing complexity increases
Solution Approach 1:
The patent employs a self-service washing approach where deionized water naturally removes Li impurities through simple contact and rinsing, eliminating the need for complex chemical treatments or advanced purification equipment while still achieving improved electrochemical 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 solution effectively reduces Li impurities on the surface, maintaining or improving the electrochemical characteristics and stability of the positive electrode, preventing gelation and swelling, and ensuring stable battery performance.
Implementation Method 1
a first compound, LiwNi1-(x+y+z)CoxM1yM2zO2+α, enabling lithium intercalation/deintercalation
Data Source
AI summary
The present invention relates to a positive electrode active material having improved electrochemical characteristics and improved stability, and a lithium secondary battery using a positive electrode including the positive electrode active material, and more particularly, to a positive electrode active material which may prevent decreases in electrochemical characteristics and stability of the positive electrode active material, which are caused by Li impurities, in advance by controlling the content of the Li impurities remaining on the surface of the positive electrode active material without a washing process to reduce the amount of residual lithium present on the surface thereof, and a lithium secondary battery using a positive electrode containing the positive electrode active material.