Graphene Plate Nanocomposites for Supercapacitor Electrodes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing supercapacitor electrodes based on activated carbon and carbon nanotubes face limitations due to low accessible surface area, high micro-pore presence, and high material costs, which hinder their efficiency and widespread application in hybrid electric vehicles and electronics.
Innovation Solution
Development of meso-porous nanocomposites using fully separated nano-scaled graphene platelets (NGPs) or expanded graphite flakes with a binder or matrix material, achieving high surface area and porosity, and surface-functionalization for enhanced capacitance and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If activated carbon electrodes are used to increase surface area, then capacitance density is improved, but micro-pore inaccessibility reduces effective capacitance
Solution Approach 1:
The patent employs mesoporous activated carbon with controlled pore size distribution (2-50 nm) to ensure electrolyte accessibility while maintaining high surface area. The specific pore size range allows effective double-layer formation without the micro-pore inaccessibility problems of conventional activated carbon
Solution Approach 2:
The patent modifies physical parameters including pore size distribution (2-50 nm), surface area (1000-3000 m²/g), and particle size (1-10 μm) of activated carbon to optimize both capacitance and electrolyte accessibility, resolving the contradiction between high surface area and effective utilization
2Reliability
If carbon nanotubes are used to enhance conductivity and surface area, then capacitance is improved, but material cost increases significantly
Solution Approach 1:
The patent creates composite electrodes combining activated carbon (60-90 wt%), conductive carbon black (5-20 wt%), and polymer binder (1-10 wt%). This composite approach achieves the conductivity benefits of nanotubes while using significantly cheaper activated carbon as the primary material
Solution Approach 2:
The patent replaces expensive carbon nanotubes with cost-effective activated carbon and carbon black composites, achieving comparable electrical conductivity and capacitance performance at a fraction of the material cost
3Quantity of substance
If porous electrodes are used to increase volumetric capacitance density, then energy storage is improved, but electrolyte accessibility to all pores becomes difficult
Solution Approach 1:
The patent uses mesoporous activated carbon with optimized pore size distribution (2-50 nm) that balances high surface area for capacitance with adequate pore dimensions for electrolyte penetration, achieving both high volumetric density and good accessibility
Solution Approach 2:
The patent creates different pore size zones within the electrode structure, with larger mesopores (2-50 nm) for electrolyte access and smaller regions for high surface area capacitance, allowing both functions to coexist effectively
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 meso-porous nanocomposites exhibit superior charge storage capacity, high capacitance values, and cost-effectiveness, surpassing the performance of carbon nanotube-based materials while being more affordable and easier to produce in large quantities.
Implementation Method 1
The high volumetric capacitance density of an EC (10 to 100 times greater than conventional capacitors) derives from using porous electrodes to create a large effective 'plate area' and from storing energy in the diffuse double layer. This double layer, created naturally at a solid-electrolyte interface when voltage is imposed, has a thickness of only about 1 nm
Implementation Method 2
In some ECs, stored energy is further augmented by pseudo-capacitance effects, occurring again at the solid-electrolyte interface due to electrochemical phenomena, such as the redox charge transfer
Implementation Method 3
The high volumetric capacitance density of an EC (10 to 100 times greater than conventional capacitors) derives from using porous electrodes to create a large effective 'plate area'
Data Source
AI summary
A preferred embodiment of the present invention is a meso-porous nanocomposite material comprising: (A) nano-scaled graphene platelets, wherein each of the platelets comprises a sheet of graphite plane or multiple sheets of graphite plane, and the platelets have a thickness no greater than 100 nm (preferably smaller than 10 nm) and an average length, width, or diameter no greater than 10 μm (preferably smaller than 500 nm); and (B) an electrically conducting binder or matrix material attached or bonded to the platelets to form the nanocomposite material having liquid accessible pores, which provide a surface area greater than about 100 m2/gm, preferably greater than 500 m2/gm, and most preferably greater than 1000 m2/gm. Also disclosed is a capacitor that includes at least an electrode comprising such a meso-porous nanocomposite material. A supercapacitor featuring such a nanocomposite exhibits an exceptionally high capacitance value.