Activated Carbon Electrode Pore Optimization for Electric Double-Layer Capacitors

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Solution Overview

Problem

Current electric double-layer capacitors have insufficient electrostatic capacity per unit volume, which limits their energy storage capacity in compact forms, particularly in applications like battery-powered vehicles and portable electronics.

Innovation Solution

Development of an activated carbon electrode using a carbonized and activated compound with specific structural and chemical properties, including a hydrocarbon group and a hydrogen atom, which enhances electrostatic capacity when used in electric double-layer capacitors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If activated carbon with micropores (20 Å or less) is used as electrode material, then electrostatic capacity per unit weight is improved, but electrostatic capacity per unit volume is insufficient

Engineering Contradiction:

Improveelectrostatic capacity per unit weightVSAvoidelectrostatic capacity per unit volume

Core Design Contradiction:

Quantity of substanceVSVolume of stationary object

Solution Approach 1:

The invention changes the pore size parameter from micropores (20 Å or less) to mesopores (20-200 Å), specifically optimizing the pore diameter distribution to achieve both high electrostatic capacity per unit weight and high electrostatic capacity per unit volume. This parameter change resolves the contradiction by finding an optimal pore size range that balances surface area availability with packing density.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses a composite electrode structure combining activated carbon particles with specific pore structures (mesopores as major pores) and conductive agents, creating a material system that achieves both high surface area for charge storage and efficient packing for high volumetric capacity.

Inventive Principle:

Principle #40Composite materials

2Volume of stationary object

If activated carbon with mesopores (20 Å or more) is used as electrode material, then electrostatic capacity per unit volume is improved, but electrostatic capacity per unit weight is insufficient

Engineering Contradiction:

Improveelectrostatic capacity per unit volumeVSAvoidelectrostatic capacity per unit weight

Core Design Contradiction:

Volume of stationary objectVSQuantity of substance

Solution Approach 1:

The invention optimizes the pore size parameter within the mesopore range (20-200 Å), specifically targeting a pore diameter of 30-150 Å to maximize both volumetric and gravimetric electrostatic capacity. This precise parameter optimization resolves the contradiction by identifying the optimal subset of mesopore sizes that balance packing efficiency with surface area availability.

Inventive Principle:

Principle #35Parameter changes

3Quantity of substance

If electrode material is designed to increase electrostatic capacity, then energy storage capacity is improved, but device size increases

Engineering Contradiction:

Improveenergy storage capacityVSAvoiddevice size

Core Design Contradiction:

Quantity of substanceVSVolume of stationary object

Solution Approach 1:

The invention changes the pore size parameter to mesopores (20-200 Å) with optimal diameter (30-150 Å), which increases the surface area-to-volume ratio of the electrode material. This allows more charge storage sites per unit volume, thereby increasing energy storage capacity without proportionally increasing device size.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention employs porous activated carbon material with optimized mesopore structure, where the porous architecture provides high surface area for charge storage while maintaining low material density. This enables high energy storage capacity in a compact form factor, resolving the contradiction between capacity and size.

Inventive Principle:

Principle #31Porous materials

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 activated carbon electrode significantly increases electrostatic capacity per unit volume, enabling more efficient energy storage in compact devices.

Implementation Method 1

store electric power in a boundary surface (electric double-layer) formed between an electrolyte and an electrode due to absorption of the electrolyte dissolved in an the electrolytic solution to the electrode

Methodology Applied

Scientific EffectAbsorption: Absorption (physical)

Implementation Method 2

store electric power in a boundary surface (electric double-layer) formed between an electrolyte and an electrode

Methodology Applied

Scientific EffectElectric double-layer formation: Electrostatics

Data Source

PatentUS7785495B2Electric double-layer capacitor

Publication Date: 2010.08.31 SUMITOMO CHEM CO LTD

AI summary

An activated carbon comprising a carbonized and activated compound represented by the formula (1):(wherein, R represents a hydrocarbon group having 1 to 12 carbon atoms, said hydrocarbon group may be optionally substituted with hydroxyl group, alkyl group, alkoxy group, aryl group, aryloxy group, sulfonyl group, halogen atoms, nitro group, thioalkyl group, cyano group, carboxyl group, amino group or amide group, R′ represents hydrogen atom or methyl group, and n represents an integer of 4, 6, or 8).