N-P Doped Porous Graphene Supercapacitor for High Volumetric Power Density
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Solution Overview
Problem
Conventional supercapacitors face limitations in achieving high volumetric energy and power density due to unsuitable pore sizes for high-viscosity ionic liquids and the use of environmentally harmful organic solvents, as well as limited potential windows of aqueous solutions.
Innovation Solution
A supercapacitor design incorporating nitrogen-phosphorus (N-P) doping porous graphene as the electrode material combined with an ionic liquid electrolyte, specifically using 1-Ethyl-3-methylimidazolium (EMI) and Bis(fluorosulfonyl)imide (FSI) for improved ion adsorption and desorption, enhancing the operating potential window and tap density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional supercapacitors use organic solvent electrolytes to achieve wider potential windows and higher energy density, then the energy storage capacity is improved, but the environmental harm and safety risks increase due to volatility, toxicity and flammability
Solution Approach 1:
The patent changes the fundamental parameter of electrolyte type from organic solvent to ionic liquid, which fundamentally alters the safety and environmental properties while maintaining or improving energy density. Ionic liquids provide wide potential windows (4-5 V or more) without the volatility, toxicity and flammability of organic solvents, thus resolving the contradiction between energy density and environmental harm
Solution Approach 2:
The patent uses composite electrode material consisting of porous graphene doped with both nitrogen and phosphorus. This composite structure combines the high surface area of porous graphene with the enhanced electrical conductivity and catalytic activity provided by the dual doping, achieving high energy density without compromising safety
2Object-affected harmful factors
If aqueous solution electrolytes are used to ensure safety and environmental friendliness, then the harmful factors are reduced, but the potential window is limited to about 1 V due to water decomposition, reducing energy density
Solution Approach 1:
The patent changes the electrolyte from aqueous solution to ionic liquid, which fundamentally expands the potential window from 1 V (water decomposition limit) to 4-5 V or more. Ionic liquids do not suffer from water decomposition, allowing much higher operating voltages and thus higher energy density while maintaining safety and environmental friendliness
3Ease of manufacture
If commercial active carbon electrodes are used with conventional pore sizes, then the manufacturing is simplified, but the volumetric energy density and power density are limited due to unsuitability for high-viscosity ionic liquids
Solution Approach 1:
The patent employs porous graphene with specifically optimized pore sizes that are suitable for ionic liquid infiltration. The porous structure provides high surface area for charge storage while the pore size is tuned to accommodate the high-viscosity ionic liquid, enabling fast ion transport and thus high volumetric power density
Solution Approach 2:
The patent applies nitrogen and phosphorus doping at specific locations within the graphene structure to enhance local electrical conductivity and catalytic activity. This local quality enhancement improves ion adsorption/desorption kinetics without requiring complete restructuring of the entire electrode, balancing manufacturing ease with performance
4Power
If graphene with quasi-2D structure is used to enhance ion adsorption and desorption, then the power density is improved, but the manufacturing complexity increases compared to conventional active carbon
Solution Approach 1:
The patent changes the electrode material from conventional 3D active carbon to 2D porous graphene, fundamentally improving ion adsorption/desorption kinetics and power density. The 2D structure provides shorter ion transport paths and higher surface area utilization, though it requires more sophisticated synthesis methods
5Use of energy by moving object
If nitrogen and phosphorus doping is applied to porous graphene to enhance electrical conductivity and ion adsorption, then the volumetric energy and power density are improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent performs nitrogen and phosphorus doping during the graphene synthesis process itself, rather than as a separate post-processing step. This preliminary action integrates the doping into the material formation, achieving the desired compositional properties without adding significant manufacturing 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 N-P doping porous graphene supercapacitor achieves enhanced volumetric energy and power density, with a notable increase in volumetric power density to 1.19 kW/L, while being environmentally friendlier than traditional designs.
Implementation Method 1
nitrogen and phosphorus doping porous graphene material
Implementation Method 2
improved ion adsorption and desorption
Implementation Method 3
ionic liquid electrolyte... high ionic conductivity and high ionic concentration
Implementation Method 4
porous graphene material
Implementation Method 5
facilitate high-power operation due to high ionic conductivity
Data Source
AI summary
A high volumetric energy and power density supercapacitor is provided. This supercapacitor includes a coin cell, a spring lamination, a working electrode, a counter electrode, a separator, and an ionic liquid electrolyte. The working and counter electrodes are N—P doping porous graphene coated on Al substrate. The ionic liquid electrolyte is EMI-FSI. The method of producing N—P doping porous graphene includes following steps: S1: Graphite oxide is quickly transferred into the furnace, which had been held at 300° C. and the porous graphene can be produced. S2: The porous graphene and red phosphorus are put together in the evacuated tube furnace and heated to 700° C. for 1 hr. S3: Heated to 800° C. for 30 min in a mixed argon and ammoniac atmosphere and then the N—P doping porous graphene can be made. The capacitance of the supercapacitor is 105 F/g and the volumetric power density is 1.19 kW/L.