Carbon-Coated Graphite Anode Particle Sizing for Low-Temperature Charging
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Solution Overview
Problem
Batteries exhibit poor fast charging capability in low-temperature environments, requiring longer charging times due to decreased conductivity of the electrolyte solution and increased impedance, which is not effectively addressed by existing methods.
Innovation Solution
A negative-electrode active material with specific particle size distributions (Dv50: 3 µm ≤ Dv50 ≤ 7 µm, Dv1 ≤ 1.5 µm, and optionally Dv99 ≤ 18 µm) and a carbon layer on artificial graphite particles, enhancing lithium ion diffusion and reducing side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the particle size of negative electrode active material is reduced to improve lithium ion diffusion, then the charging speed improves, but the side reaction with electrolyte solution increases
Solution Approach 1:
The patent applies local quality by creating a carbon layer coating on the surface of graphite particles with specific size ranges. This coating provides different properties at different locations: the interior graphite particles maintain their diffusion advantages while the exterior carbon layer suppresses side reactions. The specific particle size distribution (Dv50: 3-7 µm, Dv1 ≤ 1.5 µm) optimizes this local quality effect.
Solution Approach 2:
The patent uses composite materials by combining graphite particles with a carbon layer coating. This composite structure integrates the high lithium ion diffusion capability of graphite with the protective properties of the carbon layer, resolving the contradiction between fast charging and reduced side reactions.
2Productivity
If the particle size distribution is optimized to improve low-temperature charging performance, then the charging capability improves, but the manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by specifying precise particle size distribution parameters (Dv50: 3-7 µm, Dv1 ≤ 1.5 µm, Dv99 ≤ 18 µm) to optimize low-temperature charging performance. These parameter specifications enable manufacturers to control the particle size distribution within defined ranges to achieve the desired performance improvement.
3Stability of the object's composition
If the graphitization degree is increased to improve structural stability, then the cycling performance improves, but the lithium ion diffusion capability decreases
Solution Approach 1:
The patent applies local quality by creating a carbon layer coating on the surface of graphite particles with specific size ranges. This coating provides different properties at different locations: the interior graphite particles maintain their diffusion advantages while the exterior carbon layer suppresses side reactions. The specific particle size distribution (Dv50: 3-7 µm, Dv1 ≤ 1.5 µm) optimizes this local quality effect.
Solution Approach 2:
The patent uses composite materials by combining graphite particles with a carbon layer coating. This composite structure integrates the high lithium ion diffusion capability of graphite with the protective properties of the carbon layer, resolving the contradiction between fast charging and reduced side reactions.
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
Improves low-temperature fast charging performance and high-temperature cycling performance by optimizing lithium ion diffusion pathways and reducing polarization, while maintaining high energy density.
Implementation Method 1
the diffusion capacity of lithium ions in the negative-electrode active material and the negative-electrode film layer can be simultaneously improved
Implementation Method 2
reducing polarization, while maintaining high energy density
Data Source
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AI summary
The present application relates to a negative-electrode active material, a negative electrode plate, a battery and an electrical apparatus. The negative-electrode active material includes an artificial graphite particle and a carbon layer disposed on at least a portion of a surface of the artificial graphite particle, where a volume average particle size Dv50 of the negative-electrode active material satisfies: 3 µm ≤ Dv50 ≤ 7 µm; and a volume distribution particle size Dv1 of the negative-electrode active material satisfies: Dv1 ≤ 1.5 µm.