Carbon-Coated Graphite Anode Particles for Low-Temperature Fast 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 electrolyte conductivity 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, thereby improving low-temperature charging performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the battery uses conventional negative electrode materials with larger particle sizes, then the energy density is improved, but the lithium ion diffusion capability deteriorates at low temperatures
Solution Approach 1:
The negative electrode active material is segmented into specific particle size distributions (Dv50: 3-7 μm, Dv1 ≤ 1.5 μm), creating a multi-size particle system where smaller particles enhance low-temperature diffusion while larger particles contribute to energy density
Solution Approach 2:
The invention changes the particle size parameters of the negative electrode material, specifically controlling Dv50 between 3-7 μm and Dv1 ≤ 1.5 μm, to optimize both diffusion speed and energy density at low temperatures
2Quantity of substance
If the battery operates at low temperatures, then the fast charging capability deteriorates due to increased impedance, but the energy density is maintained
Solution Approach 1:
The negative electrode material exhibits local quality variations through its particle size distribution, where finer particles (Dv1 ≤ 1.5 μm) provide enhanced surface area and reaction sites for fast charging, while the overall distribution maintains energy density
Solution Approach 2:
The invention uses a composite particle size distribution system combining particles of different sizes (Dv50: 3-7 μm with Dv1 ≤ 1.5 μm) to achieve both high energy density and improved fast charging capability at low temperatures
3Speed
If the particle size of the negative electrode active material is reduced, then the lithium ion diffusion path is shortened and fast charging is improved, but the side reactions with electrolyte increase
Solution Approach 1:
The invention optimizes the particle size parameters by setting Dv50 between 3-7 μm and Dv1 ≤ 1.5 μm, finding the optimal balance where diffusion is enhanced without excessive fine powder that would cause harmful side reactions
Solution Approach 2:
The invention applies partial reduction in particle size (controlling the proportion of fine particles through Dv1 specification) rather than complete size reduction, achieving sufficient diffusion improvement while limiting excessive fine powder that would increase 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
The solution significantly improves the kinetic performance and fast charging capability of batteries by optimizing lithium ion diffusion paths and reducing polarization, achieving rapid charging under low-temperature conditions 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
the secondary particle has a smaller particle size, which is beneficial to further shortening the migration path of lithium ions and improve the low-temperature fast charging capability
Data Source
AI summary
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.