Graphite Negative Electrode Composition for Fast-Charging Energy Density
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Solution Overview
Problem
Current secondary batteries face challenges in achieving high energy density and quick charging performance due to limitations in negative electrode materials, particularly with natural and artificial graphite, which result in reduced battery capacity and energy density, as well as degradation in charging and output performance.
Innovation Solution
A negative electrode comprising a combination of coated and uncoated artificial graphite particles, where the coated particles have an amorphous carbon coating and are packed between uncoated secondary particles, optimizing the particle diameter ratio to enhance energy density and quick charging capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If natural graphite is used as negative electrode active material, then cost-effectiveness is improved, but irreversible reaction and decomposition occur due to irregular structure
Solution Approach 1:
The invention changes the structural parameters of natural graphite by controlling particle size distribution (D50 between 3-10 μm) and spherical morphology, transforming the irregular structure into a controlled spherical form that reduces irreversible reactions while maintaining cost-effectiveness
Solution Approach 2:
The invention creates a composite structure by coating natural graphite particles with artificial graphite (forming a core-shell structure), combining the cost-effectiveness of natural graphite with the structural stability of artificial graphite to prevent decomposition
2Reliability
If artificial graphite is used as negative electrode active material, then initial charge/discharge efficiency is improved, but discharge capacity is reduced
Solution Approach 1:
The invention optimizes the particle size parameter by controlling the D50 of artificial graphite coating between 1-3 μm and the core particle D50 between 3-10 μm, creating a specific size distribution that enhances both charge/discharge efficiency and discharge capacity
Solution Approach 2:
The invention applies different properties to different parts of the particle system: the inner natural graphite core provides capacity while the outer artificial graphite coating provides high efficiency charge/discharge, creating local quality differentiation that resolves the contradiction
3Reliability
If coated artificial graphite is used to improve structure, then roll pressing performance is improved, but energy density is reduced
Solution Approach 1:
The invention optimizes the coating thickness parameter, controlling the artificial graphite coating to be thin (1-3 μm D50) rather than thick, which maintains roll pressing performance while minimizing volume occupation to preserve energy density
Solution Approach 2:
The invention applies a partial coating rather than full thick coating, using just enough artificial graphite to improve roll pressing performance without excessive coating that would reduce energy density
4Quantity of substance
If particle size is reduced to improve packing, then energy density is improved, but quick charging performance is reduced
Solution Approach 1:
The invention optimizes the particle size parameter to a specific range (D50: 3-10 μm) that balances packing density and ion diffusion speed, avoiding both excessive small sizes that reduce capacity and excessive large sizes that slow charging
Solution Approach 2:
The invention creates a composite particle system where the artificial graphite coating on smaller natural graphite cores provides both good packing (for energy density) and efficient ion transport pathways (for quick charging performance)
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 significantly improves energy density and quick charging performance by optimizing the packing and conductivity of the negative electrode active material, leading to enhanced output properties and reduced resistance.
Implementation Method 1
the first negative electrode active material in the form that an amorphous carbon coating layer is formed on primary artificial graphite particles is disposed between the second negative electrode active materials to contribute to improving the quick charging performance and reducing the resistance of the negative electrode
Implementation Method 2
The negative electrode includes a negative electrode active material that allows lithium ions released from the positive electrode to be intercalated and deintercalated
Data Source
AI summary
A negative electrode including a negative electrode current collector, and a negative electrode active material layer on at least one surface of the negative electrode current collector is disclosed. The negative electrode active material layer includes a negative electrode active material, which includes a first negative electrode active material and a second negative electrode active material. The first negative electrode active material is coated artificial graphite particles including primary artificial graphite particles and an amorphous carbon coating layer on a surface of the primary artificial graphite particles. The second negative electrode active material is uncoated artificial graphite particles in the form of secondary particles in which two or more primary artificial graphite particles are assembled. A ratio of an average particle diameter (D50) of the second negative electrode active material to an average particle diameter (D50) of the first negative electrode active material ranges from 1.2 to 4.7.