High-Nickel Cathode Coating to Cut Residual Alkali and Impedance
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Solution Overview
Problem
High-nickel positive electrode materials in lithium-ion batteries suffer from increased battery impedance and deteriorated cycle performance due to residual alkali on their surface, which leads to gas production and unstable material structure.
Innovation Solution
A high-nickel material coated with a layer comprising compounds of formula (I) CxHy−nOzLin and formula (II) CxHy−n−1OzLin+1, formed by reacting residual alkali with organic acids, stabilizes the material structure and reduces impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If water washing is used to reduce residual alkali on the surface of high-nickel materials, then residual alkali content decreases, but NiO-like substances are generated on the surface leading to increased battery impedance and deteriorated cycle performance
Solution Approach 1:
The patent changes the chemical parameters of the washing process by using organic acid solutions (such as acetic acid, propionic acid, or butyric acid) instead of water. This parameter change allows effective removal of residual alkali while preventing the formation of harmful NiO-like substances on the material surface, thus maintaining both low residual alkali content and good cycle performance
Solution Approach 2:
The organic acid acts as an intermediary substance that mediates between the residual alkali and the high-nickel material surface. It selectively reacts with and removes residual alkali through chemical reaction, forming a protective organic salt coating layer that prevents direct contact between water and the material surface, thereby avoiding NiO-like substance formation while maintaining structural stability
2Quantity of substance
If conventional water washing is applied to remove residual alkali, then residual alkali is reduced, but battery impedance increases due to surface NiO-like substance formation
Solution Approach 1:
The patent modifies the chemical composition parameter of the washing medium by substituting water with organic acid solutions. This parameter change enables selective removal of residual alkali through acid-base reactions while the resulting organic salt coating layer on the surface prevents impedance increase by avoiding NiO-like substance formation and maintaining surface conductivity
Solution Approach 2:
The patent converts the potentially harmful residual alkali into a beneficial organic salt coating layer through controlled chemical reaction. The organic acid reacts with residual alkali to form a thin protective layer of organic lithium salts on the surface, which actually improves material performance by preventing further degradation while maintaining low residual alkali content and low impedance
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 coating layer significantly improves cycle performance and reduces impedance by effectively removing residual alkali, enhancing the stability and efficiency of the lithium-ion battery.
Implementation Method 1
a coating layer on the surface of the high-nickel material, wherein the coating layer comprises a compound of formula (I) CxHy−nOzLin and a compound of formula (II) CxHy−n−1OzLin+1 formed by reacting residual alkali with organic acids
Data Source
AI summary
A positive electrode material for a lithium-ion battery, a method for preparing same, and a lithium-ion secondary battery including same. The positive electrode material includes a high-nickel material and a coating layer on the surface of the high-nickel material, wherein the coating layer comprises compound CxHy−nOzLin (I) of formula (I) and compound CxHy−n−1 OzLin+1 (II) of formula (II), wherein x, y, z and n are each independently integers where 1≤x≤10, 2≤y≤20, 2≤z≤12, and 1≤n≤3.