Cathode Composite Coating for Li-Ion Side-Reaction Suppression
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Solution Overview
Problem
Lithium ion secondary batteries face challenges in improving initial Coulombic efficiency and cycle performance due to side reactions between the positive electrode active material and electrolyte, leading to deteriorated performance and stability.
Innovation Solution
A positive electrode composite material is developed, featuring a high-nickel positive electrode material coated with a polysaccharide organic polymer, polyvinyl alcohol, or polypropylene alcohol, which inhibits side reactions and reduces transition metal dissolution, using a method that involves mixing the coating agents with water and organic solvents to create a uniform coating layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the surface of the positive electrode active material is coated with inorganic substances such as fluoride, alumina or manganese dioxide, then the stability of the positive electrode is improved, but the conductivity deteriorates due to low conductivity of the coating material
Solution Approach 1:
The patent applies composite coating materials comprising both inorganic substances (fluoride, alumina, or manganese dioxide) and organic substances (polysaccharides, polyvinyl alcohol, or polypropylene alcohol) to the positive electrode active material surface. This composite structure combines the stability-enhancing properties of inorganic materials with the conductivity-improving properties of organic materials, thereby simultaneously improving positive electrode stability and maintaining electrode conductivity.
2Ease of manufacture
If metaphosphates are used to coat the positive electrode sheet, then the manufacturing process is simplified, but the initial Coulombic efficiency and cycle performance cannot be effectively improved
Solution Approach 1:
The patent changes the chemical composition parameters of the coating material from conventional metaphosphates to a composite system containing inorganic substances (fluoride, alumina, or manganese dioxide) and organic substances (polysaccharides, polyvinyl alcohol, or polypropylene alcohol). This parameter change enables the coating to effectively improve initial Coulombic efficiency and cycle performance while maintaining ease of manufacture through similar application processes.
3Reliability
If the positive electrode active material is used without coating, then the conductivity is maintained, but side reactions with the electrolyte occur leading to deteriorated cycle performance
Solution Approach 1:
The patent introduces an organic coating layer comprising polysaccharides, polyvinyl alcohol, or polypropylene alcohol as an intermediary between the positive electrode active material and the electrolyte. This intermediary layer prevents direct contact and side reactions between the active material and electrolyte, thereby improving cycle performance while maintaining conductivity through the organic nature of the coating material.
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 composite material significantly enhances initial Coulombic efficiency and cycle performance by preventing particle breakage and residual alkali reduction, improving structural stability and conductivity.
Implementation Method 1
a coating layer coating the positive electrode active material, the coating layer includes one or more of a polysaccharide organic polymer, polyvinyl alcohol and polypropylene alcohol
Data Source
AI summary
A positive electrode composite material, a preparation method therefor, a positive electrode and a lithium ion secondary battery are provided. The positive electrode composite material includes: a positive electrode active material; and a coating layer coating the positive electrode active material, the coating layer includes one or more of a polysaccharide organic polymer, polyvinyl alcohol and polypropylene alcohol. The positive electrode composite material, the method for preparing the positive electrode composite material, and the positive electrode and the lithium ion secondary battery which includes the positive electrode composite material in the present application, can effectively inhibit side reactions between the positive electrode active material and an electrolyte in the lithium ion secondary battery, reduce the dissolution of transition metals in the positive electrode active material, prevent breaking of the positive electrode active material particles, and improve the initial Coulombic efficiency and cycle performance of the lithium ion secondary battery.