Graphite Composite Anode Coating for Fast-Charge Cycle Stability
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Solution Overview
Problem
Graphite negative electrode materials in lithium-ion batteries face challenges with high rate charging and discharging due to their layered structure, leading to deviations in rate performance. Existing modifications, such as reducing particle size and surface coating, do not fundamentally improve power performance and can result in uneven coating and exposure issues.
Innovation Solution
A graphite composite negative electrode material is developed, featuring a core of graphite with a coating layer composed of titanium niobate, carbon nanotubes, and amorphous carbon. This coating layer enhances the material's electrochemical performance by improving structural stability and reducing the generation of SEI films and lithium dendrites.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phenolic resin is used for surface coating of graphite, then specific capacity and recycling rate are improved, but coating uniformity deteriorates and graphite exposure occurs
Solution Approach 1:
The patent introduces a two-stage coating process where phenolic resin serves as a primary coating layer, followed by a secondary coating layer that acts as an intermediary to seal defects and achieve uniform coverage. The secondary coating material mediates between the phenolic resin coating and the graphite surface, preventing exposure while maintaining the benefits of the primary coating.
Solution Approach 2:
The patent applies preliminary surface treatment to graphite particles before coating, including surface activation and roughening processes. This preliminary action creates optimal surface conditions that enhance phenolic resin adhesion and prevent coating defects, thereby improving both coating uniformity and cycling performance.
2Productivity
If graphite particle size is reduced to improve power performance, then rate capability is enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent systematically optimizes graphite particle size parameters within specific ranges (0.5-2.0 mm for natural graphite, 0.3-1.5 mm for spherical graphite) to achieve optimal power performance while maintaining manufacturability. This parameter change approach balances rate capability improvement with manufacturing complexity control.
Solution Approach 2:
The patent creates composite graphite materials by combining different graphite types (natural graphite, spherical graphite, artificial graphite) in specific ratios. This composite approach achieves enhanced power performance through optimized particle size distribution and morphology, while simplifying the manufacturing process compared to producing ultra-fine pure graphite particles.
3Productivity
If coating layer mass ratio is increased to improve electrochemical performance, then first efficiency and power are enhanced, but material cost increases
Solution Approach 1:
The patent applies a controlled amount of coating material (0.5-5.0 mass% of total electrode material) that is sufficient to achieve the desired electrochemical performance improvement without excessive coating. This partial action approach optimizes the balance between first efficiency enhancement and coating material consumption, avoiding diminishing returns at higher coating ratios.
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 graphite composite negative electrode material exhibits improved first efficiency, power, and cycling performance, with enhanced structural stability during charge and discharge processes, and better fast charging capabilities.
Implementation Method 1
the amorphous carbon stabilizes the structure of materials, jointly improving the stability of the material's structure during the charge and discharge process
Implementation Method 2
the carbon nanotubes form a network structure, and the amorphous carbon stabilizes the structure of materials
Data Source
AI summary
A graphite composite negative electrode material, a preparation method therefor and an application thereof. A coating layer formed by mixing a plurality of substances is coated on the surface of graphite, the high theoretical specific capacity of titanium niobate is utilized, and carbon nanotubes and amorphous carbon are added in an auxiliary manner, the carbon nanotubes form a network structure, and the amorphous carbon stabilizes the structure of the material, which jointly improve the structural stability of the material in the charging and discharging process, and improve the first efficiency and the cycle performance of the material.