Nitride-Carbon Nanosheet Cathode Coating for Fast-Charge Stability
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Solution Overview
Problem
Existing coating methods for ternary positive electrode materials in lithium-ion batteries, such as gas phase deposition and one-step mixed sintering, are complex and prone to damaging the lattice structure of the material, affecting its performance.
Innovation Solution
A nitride/graphitized carbon nanosheet-coated ternary positive electrode material is developed, where the graphitized carbon is formed in situ during the nitride coating process, creating a denser conductive network and improving the material's rate performance and cycle stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If gas phase deposition coating method is used, then coating quality is improved, but process complexity increases and large-scale production becomes difficult
Solution Approach 1:
The patent replaces the complex gas phase deposition process with a simpler wet chemical coating method followed by low-temperature sintering. This substitution uses liquid precursors and chemical reactions instead of complex gas phase equipment and processes, achieving comparable or superior coating quality while dramatically simplifying the manufacturing process for large-scale production.
Solution Approach 2:
The patent changes the processing parameters from high-temperature gas phase deposition to low-temperature wet chemical coating and sintering. By adjusting the coating temperature and using liquid precursors, the process becomes simpler and more suitable for large-scale production while maintaining coating quality.
2Ease of manufacture
If one-step mixed sintering method is used, then process simplicity is improved, but lattice structure of ternary material is damaged
Solution Approach 1:
The patent divides the coating process into separate steps: first coating the ternary material with a precursor solution, then performing low-temperature sintering to form the nitride coating. This segmentation allows the coating process to proceed at lower temperatures that do not damage the underlying ternary material lattice structure, while still achieving complete coating coverage.
Solution Approach 2:
The patent applies preliminary coating action by first depositing the nitride precursor on the ternary material surface, then performing low-temperature sintering to convert the precursor to nitride. This preliminary coating prevents direct exposure of the ternary material to harsh reducing gases, protecting the lattice structure while achieving effective coating.
3Reliability
If oxide coating agent is used, then interface stability is improved, but electronic conductivity decreases
Solution Approach 1:
The patent uses nitride compounds instead of oxide coating agents. Nitrides provide both the desired interface stability and superior electronic conductivity compared to oxides. The nitride coating forms a stable protective layer while maintaining good electrical conductivity, enabling fast ion conduction and meeting high current charging and discharging requirements.
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 proposed solution enhances the rate performance and cycle stability of the ternary positive electrode material, while simplifying the preparation method and making it suitable for large-scale industrial production.
Implementation Method 1
the coating element is coated on the surface of the ternary positive electrode material matrix by wet coating to obtain an intermediate product
Implementation Method 2
the intermediate product is mixed with the carbonaceous and nitrogenous compound evenly, and the nitride/graphitized carbon nanosheet-coated ternary positive electrode material is obtained after sintering
Implementation Method 3
graphitized carbon is formed in situ in the coating process of the nitride
Implementation Method 4
The coating agent can also act as a fast ion conductor to provide a good channel for lithium ion diffusion and transmission
Data Source
AI summary
The invention discloses a nitride/graphitized carbon nanosheet-coated ternary positive electrode material and preparation method therefor. The nitride/graphitized carbon nanosheet-coated ternary positive electrode material includes a ternary positive electrode material matrix and a coating layer; the coating layer is composed of nitride and graphitized carbon; and the graphitized carbon is formed in situ in the coating process of the nitride. Compared with a physical mixing method, the in-situ generated carbon layer is connected to the material matrix more tightly, and the formed conductive network is denser. So that the rate performance of the material is improved to the maximum extent. The preparation method is simple and easy to realize industrial production. And the obtained nitride/graphitized carbon nanosheet-coated ternary positive electrode material has excellent rate performance and cycling stability.