Lithium Ion Cathode Carbon Coating Ratio Control
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Solution Overview
Problem
The challenge lies in achieving a high-performance lithium ion battery cathode material with optimal carbon coating, where increasing the carbon coating ratio leads to carbon deposition elsewhere than on the particle surfaces, resulting in decreased powder density and handling issues during production.
Innovation Solution
A cathode material with a specific carbon-to-BET specific surface area ratio of 0.08 to 0.2, tap density of 0.9 g/cm3 to 1.5 g/cm3, and an oil absorption amount of 70 cc/100 g or less, featuring a central particle with a carbonaceous coating layer including LixAyDzPO4 and LiwEbGO4 compounds, ensuring uniform electron conductivity and high discharge potential.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amount of carbon source is increased to increase the carbon coating ratio, then the carbon coating effect is improved, but carbon having insufficient degree of carbonization remains at places other than particle surfaces, causing decrease in powder density and deterioration of handling properties
Solution Approach 1:
The patent applies parameter changes by precisely controlling the carbon-to-BET specific surface area ratio within 0.08 to 0.2, and controlling the tap density within 0.9 to 1.5 g/cm³. These parameter specifications ensure optimal carbon coating coverage while preventing excessive carbon deposition that would harm handling properties and powder density.
Solution Approach 2:
The patent uses partial action by applying just enough carbon coating to achieve the desired effect without over-coating. The controlled carbon ratio ensures sufficient coverage for electron conductivity improvement while avoiding the harmful effects of excessive carbon deposition on non-particle-surface areas.
2Reliability
If the amount of carbon source is increased to increase the carbon coating ratio, then the carbon coating effect is improved, but the powder density decreases
Solution Approach 1:
The patent resolves this contradiction by establishing specific parameter ranges: carbon-to-BET specific surface area ratio of 0.08 to 0.2 and tap density of 0.9 to 1.5 g/cm³. These parameters balance the carbon coating effect with powder density maintenance, ensuring both electron conductivity improvement and adequate packing density.
3Reliability
If the carbon coating conditions are adjusted to improve coating ratio and carbonization degree, then the electron conductivity is improved, but the conditions are affected by various particle properties making stable provision difficult
Solution Approach 1:
The patent simplifies the complex control of carbon coating conditions by establishing a universal parameter specification: carbon-to-BET specific surface area ratio of 0.08 to 0.2. This single ratio parameter accounts for variations in particle diameter, shape, and agglomeration state, providing a stable and reproducible method to achieve optimal electron conductivity without complex adjustments.
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
This approach enables the production of high-performance lithium ion batteries with improved electron conductivity, discharge potential, and handling properties, while maintaining a balanced carbon coating that prevents excessive carbon deposition and enhances battery stability.
Implementation Method 1
techniques of coating the surfaces of cathode active materials with a carbonaceous material (hereinafter, in some cases, simply referred to as carbon coating) are known
Implementation Method 2
a method is known in which a carbon source and a cathode material are mixed together and the mixture is fired in an inert atmosphere or a reducing atmosphere
Data Source
AI summary
A cathode material including an aggregate formed by aggregating active material particles, in which the active material particle is a particle including a cathode active material as a formation material and a carbonaceous material is provided on a surface of the particle, a ratio between a weight ratio of carbon contained in the aggregate to a BET specific surface area of the cathode material is in a range of 0.08 to 0.2, a tap density is in a range of 0.9 g/cm3 to 1.5 g/cm3, and an oil absorption amount for which N-methyl-2-pyrrolidone is used is 70 cc/100 g or less.