Cathode Coating Liquid for Uniform Aluminum Phosphate Layer
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Solution Overview
Problem
Conventional methods for coating aluminum phosphate on cathode active materials in lithium ion batteries result in a non-uniform coating layer due to the insolubility of aluminum phosphate in water, leading to poor cycling performance and thermal stability.
Innovation Solution
A cathode active material coating liquid is developed, comprising a solvent and a soluble aluminum phosphate ester complex, which forms a homogeneous clear solution when mixed with an aluminum salt, allowing for a uniform and thin coating layer on the cathode active material particles through a process involving phosphate ester solution formation, aluminum salt introduction, mixing, and sintering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If aluminum phosphate particles are dispersed in water to form a dispersion liquid for coating, then the coating process can be implemented, but the coating layer is not uniform due to insolubility of aluminum phosphate in water
Solution Approach 1:
The patent changes the physical state of aluminum phosphate from insoluble particles to soluble complexes by modifying its chemical form. Aluminum phosphate is converted into soluble complexes such as aluminum phosphate esters or aluminum phosphate salts that can dissolve in water, enabling uniform distribution and coating formation.
Solution Approach 2:
The patent introduces intermediate compounds (aluminum phosphate esters or aluminum phosphate salts) as mediators between aluminum phosphate and water. These intermediates are soluble in water and can be uniformly dispersed, then decompose during sintering to form the desired aluminum phosphate coating layer.
2Temperature
If a coating layer is formed on cathode active material particles, then thermal stability is improved, but the coating layer may reduce electrochemical performance if too thick
Solution Approach 1:
The patent controls the concentration of aluminum phosphate complexes in the coating liquid and the sintering conditions to precisely control the thickness of the coating layer. By adjusting these parameters, a thin uniform coating layer is formed that provides thermal stability while minimizing impact on electrochemical performance.
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 enables the formation of a thin, uniform coating layer that enhances thermal stability and capacity retention of lithium ion batteries without compromising electrochemical performance by preventing side reactions and ensuring complete surface coverage of cathode active material particles.
Implementation Method 1
introducing an aluminum salt to the phosphate ester solution, the aluminum salt being soluble to the alcoholic solvent, and the aluminum salt reacting with the phosphate ester to form a homogeneous clear solution
Implementation Method 2
the aluminum salt reacting with the phosphate ester to form a homogeneous clear solution
Implementation Method 3
drying and sintering the solid-liquid mixture to obtain a cathode composite material, the cathode composite material including the cathode active material and a coating layer coated on a surface of the cathode active material
Implementation Method 4
drying and sintering the solid-liquid mixture
Data Source
AI summary
The present disclosure relates to a method for making a cathode active material coating liquid including steps: forming a phosphate ester solution by adding a phosphate ester in an alcoholic solvent; and introducing an aluminum salt to the phosphate ester solution, the aluminum salt being soluble to the alcoholic solvent, and the aluminum salt reacting with the phosphate ester to form a homogeneous clear solution. The present disclosure also relates to a cathode active material coating liquid and a method for coating the cathode active material.