Carbon-Coated Graphite Anode for Stable Electrolyte Interface Kinetics
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Solution Overview
Problem
Traditional graphite-based anode materials in lithium-ion batteries suffer from surface defects and poor compatibility with electrolytes, leading to irreversible side reactions, low initial Coulombic efficiency, and continuous capacity degradation due to uncontrolled surface and interface structure.
Innovation Solution
An anode material comprising graphite with a carbon layer on its surface, characterized by specific Raman ratio (A-B) and surface roughness (S) ranges, ensuring a uniform carbon layer distribution and proper interface structure for improved lithium-ion transport kinetics and reduced impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional graphite-based materials are used as anode materials, then cost-effectiveness is improved, but surface defects and poor compatibility with electrolytes lead to severe irreversible side reactions, low initial Coulombic efficiency, and continuous capacity degradation
Solution Approach 1:
The patent applies composite materials by combining graphite particles with a carbon coating layer formed through in-situ polymerization of styrene monomer. This composite structure maintains the cost-effectiveness of graphite while the carbon coating layer eliminates surface defects and improves electrolyte compatibility, thereby resolving the contradiction between manufacturing ease and initial Coulombic efficiency.
Solution Approach 2:
The patent changes the physical and chemical parameters of the graphite surface by forming a carbon coating layer with specific thickness (5-50 nm) and structure (amorphous carbon). This parameter change transforms the defective graphite surface into a smooth, defect-free interface that prevents irreversible side reactions while maintaining cost-effectiveness.
2Object-affected harmful factors
If surface coating methods are employed to modify graphite, then direct contact between electrolyte and natural graphite is reduced, but existing coating processes cannot precisely control the surface and internal interface characteristics, leading to poor lithium-ion transport kinetics and low capacity
Solution Approach 1:
The patent uses styrene monomer as an intermediary substance that undergoes in-situ polymerization to form a carbon coating layer. This intermediary approach allows precise control of the coating thickness and structure by adjusting polymerization conditions (monomer concentration, temperature, time), thereby achieving both side reaction reduction and precise interface characteristic control.
Solution Approach 2:
The patent applies preliminary action by pre-forming the carbon coating layer on graphite particles before battery assembly through in-situ polymerization. This preliminary coating process precisely controls the surface and interface characteristics, preventing subsequent side reactions while ensuring optimal lithium-ion transport kinetics.
3Reliability
If a carbon layer is added on graphite surface to improve performance, then lithium-ion transport kinetics and initial Coulombic efficiency are improved, but device complexity increases
Solution Approach 1:
The patent applies self-service by using in-situ polymerization where the styrene monomer automatically polymerizes on the graphite surface under controlled conditions to form the carbon coating layer. This self-assembling process eliminates the need for complex external coating equipment and multiple processing steps, thereby improving lithium-ion transport kinetics without significantly increasing device complexity.
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 anode material achieves high capacity, low impedance, and high initial efficiency by optimizing the carbon layer's disorder and flatness, enhancing electrolyte infiltration and interface transport kinetics.
Implementation Method 1
When a particle surface and a particle section of the anode material are respectively tested by Raman spectroscopy, a peak area ratio of D characteristic peak within a range of 1300 cm−1 to 1350 cm−1 to G characteristic peak within a range of 1500 cm−1 to 1580 cm−1 is ID/IG
Implementation Method 2
When a particle surface of the anode material is tested by adopting an atomic force microscopy, a 1 μm×1 μm test region is randomly selected on the particle surface of the anode material, an arithmetic average value of height deviation absolute values relative to a reference surface in the test region is S nm
Data Source
AI summary
Anode material, preparation method thereof, and battery. Anode material includes graphite and carbon layer located on at least part of surface of graphite. Particle surface and particle section of anode material are respectively tested by Raman spectroscopy, peak area ratio of D characteristic peak within range of 1300 cm−1 to 1350 cm−1 to G characteristic peak within range of 1500 cm−1 to 1580 cm−1 is ID/IG, ratio of ID/IG measured on the particle surface is A, and ratio of ID/IG measured on particle section is B, and 1.22<A-B≤2.10. Particle surface of anode material is tested by adopting atomic force microscopy, 1 μm×1 μm test region is randomly selected on particle surface of anode material, arithmetic average value of height deviation absolute values relative to reference surface in test region is S nm, where 15 nm≤S≤60 nm. Anode material improves lithium-ion transport kinetics, initial Coulombic efficiency, and cycle performance.