Natural Graphite Anode with Amorphous Carbon Coating
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Solution Overview
Problem
Natural graphite anodes for lithium secondary batteries face issues with irregular structure, electrolyte decomposition, and reduced charging and discharging efficiency due to swelling, which affects stability and reliability.
Innovation Solution
An anode with a current collector and an anode active material layer comprising natural graphite particles with a high electrode density and an amorphous carbon layer, where the XRD orientation index is controlled to improve electrolyte wet-ability and suppress particle deformation, enhancing charging properties and lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If natural graphite is used as anode active material, then capacity and cost are improved, but structure irregularity and swelling occur leading to reduced charging and discharging efficiency
Solution Approach 1:
The patent applies spheroidization treatment to transform irregular natural graphite particles into spherical shapes with controlled size distribution (D50: 5-15 μm). This parameter change in particle morphology eliminates structure irregularity and prevents swelling during lithium insertion/extraction, thereby maintaining high charging and discharging efficiency while preserving the high capacity advantage of natural graphite.
Solution Approach 2:
The patent creates a composite structure by coating the spheroidized natural graphite particles with an amorphous carbon layer (1-10 μm thickness). This composite material approach combines the high capacity of natural graphite with the structural stability and conductivity of amorphous carbon, preventing particle deformation and swelling while maintaining excellent charging and discharging efficiency.
2Reliability
If natural graphite particles are coated with amorphous carbon layer, then particle deformation is suppressed and charging properties are enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent performs spheroidization treatment and amorphous carbon coating as preliminary actions during the anode material preparation stage, before electrode fabrication. By pre-treating the natural graphite particles with controlled spheroidization and coating, the patent simplifies subsequent electrode manufacturing processes while ensuring optimal particle morphology and surface properties for high charging performance.
3Quantity of substance
If electrode density is increased to 1.50 g/cc or more, then battery energy density is improved, but particle swelling and electrolyte decomposition are exacerbated
Solution Approach 1:
The patent achieves high electrode density (1.50 g/cc or more) by controlling particle size distribution (D50: 5-15 μm) and sphericity (0.93 or more) through spheroidization treatment. The spherical morphology and narrow size distribution enable tight particle packing at high density while minimizing void spaces where electrolyte decomposition could occur, thus achieving high energy density without exacerbating electrolyte decomposition.
Solution Approach 2:
The amorphous carbon coating layer (1-10 μm) on the spheroidized natural graphite particles acts as a protective barrier that prevents direct contact between the graphite surface and electrolyte. This composite structure allows the electrode to be packed at high density (1.50 g/cc or more) while the carbon coating suppresses electrolyte decomposition reactions, maintaining particle stability and preventing swelling even at high packing densities.
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 improves the stability, reliability, and high-temperature storage properties of lithium secondary batteries by maintaining high capacity and efficiency while reducing particle expansion and enhancing electrolyte interaction.
Implementation Method 1
natural graphite particles... having an electrode density of 1.50 g/cc or more... I(004) is a peak intensity corresponding to a (004) plane of the anode active material obtained by an XRD measurement
Implementation Method 2
natural graphite may have an irregular structure, and may cause a swelling due to an electrolyte decomposition reaction occurring at an edge portion thereof
Implementation Method 3
the preliminary anode active material layer is pressed to form an anode active material layer having an electrode density of 1.50 g/cc or more
Implementation Method 4
I(004) is a peak intensity corresponding to a (004) plane of the anode active material obtained by an XRD measurement from the anode active material layer
Data Source
AI summary
An anode for a lithium secondary battery according to an embodiment of the present invention includes a current collector, and an anode active material layer coated on the current collector. The anode active material layer includes an anode active material that includes natural graphite particles, and has an electrode density of 1.50 g/cc or more. An XRD orientation index defined as I(004)/I(110) is 8 or less, I(004) is a peak intensity corresponding to a (004) plane of the anode active material obtained by an XRD measurement from the anode active material layer, and I(110) is a peak intensity corresponding to a (110) plane of the anode active material obtained by the XRD measurement from the anode active material layer.