Sulfur-Doped Artificial Graphite for High-Output Battery Anodes
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Solution Overview
Problem
The existing negative electrode active materials for lithium secondary batteries, particularly artificial graphite, face challenges in improving output characteristics and capacity while maintaining high initial efficiency, as reducing particle diameter or forming a carbon coating layer can degrade performance.
Innovation Solution
Incorporating sulfur in an amount of 15 ppm to 40 ppm into artificial graphite particles to randomize the crystal structure, thereby enhancing lithium ion diffusion and preventing excessive surface area increase, which improves output characteristics and initial efficiency without reducing capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the particle diameter of artificial graphite is reduced to improve output characteristics, then output characteristics are improved, but grinding yield is reduced and capacity is reduced
Solution Approach 1:
The patent changes the chemical composition parameter by introducing sulfur (1-50 ppm) into the artificial graphite crystal structure. This compositional modification allows the graphite to achieve improved output characteristics without requiring particle size reduction, thereby avoiding the loss of grinding yield and capacity that would result from reducing particle diameter.
2Power
If the particle diameter of artificial graphite is reduced to improve output characteristics, then output characteristics are improved, but capacity is reduced
Solution Approach 1:
The patent modifies the chemical composition by incorporating sulfur (1-50 ppm) into the artificial graphite structure. This compositional change enhances output characteristics while preserving the particle size and total lithium ion capacity, thereby avoiding the capacity reduction that would result from particle size reduction.
3Power
If an amorphous carbon coating layer is formed on artificial graphite to improve output characteristics, then output characteristics are improved, but initial efficiency is reduced due to increase in specific surface area
Solution Approach 1:
The patent changes the chemical composition parameter by introducing sulfur (1-50 ppm) into the artificial graphite structure, which improves output characteristics without increasing the specific surface area. This avoids the formation of additional SEI layers that would reduce initial efficiency, unlike amorphous carbon coating which increases surface area and initial electrolyte consumption.
4Power
If an amorphous carbon coating layer is formed on artificial graphite to improve output characteristics, then output characteristics are improved, but storage performance is degraded
Solution Approach 1:
The patent modifies the chemical composition by incorporating sulfur (1-50 ppm) into the artificial graphite structure. This compositional change enhances output characteristics without creating the thick amorphous carbon layer that would increase side reactions with the electrolyte during storage, thereby preserving storage 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 negative electrode active material with sulfur distribution achieves excellent performance in terms of output characteristics, capacity, and initial efficiency, addressing the limitations of traditional artificial graphite materials.
Implementation Method 1
the sulfur is distributed in the artificial graphite particles... a diffusion path of lithium ions may be smoothly secured to improve output characteristics
Data Source
AI summary
A negative electrode active material which includes artificial graphite particles, and sulfur distributed in the artificial graphite particles, wherein the sulfur is present in an amount of 15 ppm to 40 ppm. With respect to a negative electrode and a secondary battery which include the negative electrode active material, output characteristics and capacity characteristics may be simultaneously improved, and initial efficiency may be improved.