Natural Graphite Anode Material With Amorphous Carbon Pore Filling
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Solution Overview
Problem
Natural graphite anode materials in lithium-ion batteries suffer from low initial coulombic efficiency and insufficient cycle stability due to anisotropy, solvent co-intercalation, and uneven volume expansion, leading to capacity attenuation and structural damage.
Innovation Solution
An anode material composed of natural graphite with amorphous carbon filled in its pores, with specific hardness, elastic modulus, and tablet orientation values, enhancing densification and reducing anisotropy, thereby improving lithium ion diffusion and structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If natural graphite is used as anode material, then specific capacity and cost are improved, but initial coulombic efficiency and cycle stability deteriorate
Solution Approach 1:
The patent applies local quality by filling amorphous carbon specifically into the pores and defects of natural graphite particles, creating different structural characteristics in different regions. The natural graphite maintains its crystalline structure for high capacity, while the amorphous carbon filling provides local stability and prevents solvent co-intercalation, thus resolving the contradiction between high specific capacity and cycle stability.
Solution Approach 2:
The patent creates a composite material system combining natural graphite (crystalline) with amorphous carbon. This composite structure leverages the high capacity advantage of natural graphite while utilizing the structural stability and isotropic properties of amorphous carbon to prevent expansion, cracking, and capacity attenuation, thereby improving cycle stability without sacrificing specific capacity.
2Productivity
If natural graphite undergoes intercalation of lithium ions, then charge-discharge efficiency is improved, but solvent co-intercalation occurs leading to SEI membrane instability
Solution Approach 1:
The patent applies preliminary anti-action by pre-filling the pores and defects of natural graphite with amorphous carbon before lithium ion intercalation. This preventive measure blocks the entry of solvent molecules that would otherwise co-intercalate and destabilize the SEI membrane, allowing efficient lithium ion transport while maintaining SEI stability.
3Duration of action of moving object
If natural graphite undergoes long-term cycles, then battery operation is maintained, but capacity attenuation increases due to expansion and contraction
Solution Approach 1:
The patent applies beforehand cushioning by filling amorphous carbon into the pores and defects of natural graphite prior to cycling. This amorphous carbon acts as a cushioning material that absorbs and distributes the mechanical stress during lithium ion insertion and extraction, preventing the expansion, cracking, and shedding that would otherwise occur during long-term cycling, thus maintaining capacity retention.
4Quantity of substance
If natural graphite has higher anisotropy and internal defects, then specific capacity is improved, but uneven volume expansion occurs leading to structural damage
Solution Approach 1:
The patent applies local quality by selectively filling amorphous carbon into the pores and defect regions of natural graphite particles. This creates a heterogeneous structure where the natural graphite crystalline regions maintain high capacity, while the amorphous carbon filling in the pores provides local structural support and isotropic properties, preventing uneven expansion and maintaining overall structural stability.
Solution Approach 2:
The patent creates a composite material system combining crystalline natural graphite with amorphous carbon filling. The crystalline graphite provides high specific capacity, while the amorphous carbon provides structural stability and isotropic expansion characteristics, compensating for the anisotropy and defects of natural graphite and preventing structural damage during cycling.
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 an initial coulombic efficiency of ≥94% and a capacity retention rate of ≥92.5% after 400 cycles, with improved cycle stability and electrochemical performance.
Implementation Method 1
amorphous carbon filled in pores of the natural graphite
Implementation Method 2
during intercalation of lithium ions
Implementation Method 3
promoting more uniform diffusion of lithium ions in different directions
Data Source
AI summary
Provided is an anode material, a negative electrode plate and a secondary battery, and relates to the technical field of secondary batteries. The anode material includes natural graphite and amorphous carbon filled in pores of the natural graphite; a particle hardness of the anode material is 0.28 GPa-0.4 GPa, and an elastic modulus is 7.0 GPa-8.0 GPa; and when a tablet compaction density of the anode material is 1.5 g/cm3-2.0 g/cm3, a tablet orientation OI value of the anode material is y, and 4<y≤11. When the anode material is used in the secondary battery, initial coulombic efficiency and cycle stability can be significantly improved.