Graphene Composite Conductive Material for Battery Electrodes
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Solution Overview
Problem
Current methods for improving lithium-ion battery capacity, such as using carbon nanofibers and graphene, face challenges due to high contact resistance between curved conductive assistants and active materials, leading to suboptimal theoretical capacity achievement and thermal conductivity.
Innovation Solution
A composite conductive material with a graphite-based carbon material precursor, treated to enhance exfoliation and dispersion, is used to create a graphene-like structure with a high aspect ratio, which is then dispersed to achieve efficient conductivity and thermal conductivity by reducing contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional conductive assistants (acetylene black, VGCF) are used to improve electrical conductivity, then conductivity is enhanced, but contact resistance increases due to curved surface point contacts
Solution Approach 1:
The invention inverts the conventional curved conductive assistant shape into a planar structure. Graphene's flat sheet morphology provides broad surface contact with active material particles, replacing the point contacts of curved assistants. This planar geometry reduces contact resistance while maintaining conductivity enhancement.
Solution Approach 2:
The invention creates a composite system combining graphene with conventional conductive assistants (acetylene black, VGCF). The graphene planar sheets provide low-resistance contact areas, while the curved assistants fill gaps and extend conductive networks. This composite approach leverages the complementary strengths of both material types to minimize contact resistance.
2Quantity of substance
If carbon nanofibers and graphene are added to improve capacity, then theoretical capacity can be approached, but manufacturing complexity increases
Solution Approach 1:
Graphene serves multiple functions simultaneously: it acts as a conductive assistant to reduce contact resistance, provides additional active material surface area to approach theoretical capacity, and enhances structural integrity of the electrode. This multi-functionality reduces the need for separate additive components and simplifies manufacturing.
Solution Approach 2:
The invention optimizes the amount and form of graphene added to electrodes, using small controlled quantities (0.1-5 wt%) in specific morphological forms (exfoliated, dispersed sheets). This parameter optimization achieves capacity improvement without excessive manufacturing complexity, balancing performance gains with process feasibility.
3Reliability
If more conductive assistants are interposed between active materials to improve conductivity, then electrical pathways are created, but contact resistance increases due to increased number of contact points
Solution Approach 1:
The planar geometry of graphene sheets creates large-area contact interfaces with active material particles, replacing the point contacts formed by curved conductive assistants. This geometric transformation reduces the number of effective contact points needed while maintaining conductivity pathways, thereby reducing contact resistance.
Solution Approach 2:
The invention transitions from zero-dimensional (spherical) or one-dimensional (fibrous) conductive assistants to two-dimensional planar graphene sheets. This dimensional upgrade provides extensive surface area for contact with active materials, creating efficient electrical pathways with fewer contact points and reduced resistance.
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 approach enables lithium-ion batteries to approach their theoretical capacity and enhance thermal conductivity, improving charging and discharging characteristics and heat transfer.
Implementation Method 1
a graphite-based carbon material precursor, treated to enhance exfoliation and dispersion, is used to create a graphene-like structure
Implementation Method 2
which is then dispersed to achieve efficient conductivity and thermal conductivity by reducing contact resistance
Implementation Method 3
enhance thermal conductivity, improving charging and discharging characteristics and heat transfer
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3
AI summary
Provided is a composite conductive material excellent in conductivity. The composite conductive material comprises at least graphene-like exfoliated from a graphite-based carbon material and a conductive material dispersed in a base material. The graphite-based carbon material is characterized by having a rhombohedral graphite layer (3R) and a hexagonal graphite layer (2H), wherein a Rate (3R) of the rhombohedral graphite layer (3R) and the hexagonal graphite layer (2H), based on an X-ray diffraction method, which is defined by following Equation 1 is 31% or more: Rate3R=P3/P3+P4×100 wherein P3 is a peak intensity of a (101) plane of the rhombohedral graphite layer (3R) based on the X-ray diffraction method, and P4 is a peak intensity of a (101) plane of the hexagonal graphite layer (2H) based on the X-ray diffraction method.