Soft Carbon Electrode Activation for High-Voltage Supercapacitors

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Solution Overview

Problem

The use of graphite as positive electrodes in asymmetrical supercapacitors leads to excessive gas generation due to its large specific surface area, causing water adsorption and electrolyte decomposition, which increases pressure and damages the electrodes, while existing soft carbon materials with small specific surface areas lack adequate specific capacitance and symmetrical charging and discharging curves.

Innovation Solution

A method is developed to prepare a soft carbon material with specific characteristics, including a carbon layer spacing between 0.345 nm and 0.360 nm, and crystal plane lengths less than 6 nm, through alkaline activation and electrochemical activation, resulting in a material with a low specific surface area and improved charging and discharging curves similar to electric double-layer capacitors (EDLCs).

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If graphite is used as positive electrode material, then the specific surface area is large, but excessive gas is generated due to water adsorption and electrolyte decomposition

Engineering Contradiction:

Improvespecific surface areaVSAvoidgas generation

Core Design Contradiction:

Area of stationary objectVSObject-generated harmful factors

Solution Approach 1:

The patent changes the physical and chemical parameters of the soft carbon material by controlling carbon layer spacing (0.345-0.360 nm) and crystal plane dimensions (Lc < 6 nm, La < 6 nm) to achieve optimal performance that balances surface area with reduced gas generation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses soft carbon material with specific structural characteristics as a composite electrode material, combining properties of both high surface area and controlled gas evolution through its unique layered structure

Inventive Principle:

Principle #40Composite materials

2Object-generated harmful factors

If soft carbon material with small specific surface area is used, then gas generation is reduced, but specific capacitance is inadequate

Engineering Contradiction:

Improvegas generationVSAvoidspecific capacitance

Core Design Contradiction:

Object-generated harmful factorsVSQuantity of substance

Solution Approach 1:

The patent optimizes the structural parameters of soft carbon material, specifically controlling carbon layer spacing and crystal plane dimensions, to achieve a balance between reduced gas generation and adequate specific capacitance

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates localized regions with specific structural characteristics in the soft carbon material, where the carbon layer spacing and crystal plane dimensions are controlled to provide both low gas generation and high capacitance in different areas

Inventive Principle:

Principle #3Local quality

3Object-generated harmful factors

If soft carbon material is used, then gas generation is reduced, but charging and discharging curves are not symmetrical

Engineering Contradiction:

Improvegas generationVSAvoidcharging and discharging curve symmetry

Core Design Contradiction:

Object-generated harmful factorsVSStability of the object's composition

Solution Approach 1:

The patent adjusts the structural parameters of soft carbon material, particularly carbon layer spacing and crystal plane dimensions, to achieve symmetrical charging and discharging curves while maintaining low gas generation characteristics

Inventive Principle:

Principle #35Parameter changes

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 method produces a soft carbon material suitable for high-voltage supercapacitors with enhanced specific capacitance and symmetrical charging and discharging curves, reducing the risk of electrode damage and increasing the operating voltage of asymmetrical supercapacitors.

Implementation Method 1

graphite has a large specific surface area and thus adsorbs water to a great extent

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 2

performing an alkaline activation on the initial soft carbon material with an alkaline activator

Methodology Applied

Scientific EffectAlkaline activation:

Implementation Method 3

performing an electrochemical activation on the first processing carbon material with an electrolyte

Methodology Applied

Scientific EffectElectrochemical activation:

Data Source

PatentUS11830673B2Method of preparing soft carbon material for high-voltage supercapacitor and asymmetrical supercapacitor

Publication Date: 2023.11.28 CPC CORPORATION

AI summary

A method of preparing a soft carbon material for high-voltage supercapacitors includes: providing an initial soft carbon material characterized by: (A) a first carbon layer spacing greater than 0.345 nm but less than 0.360 nm; (B) a crystal plane (002) with a length (Lc) less than 6 nm; (C) a crystal plane (101) with a length (La) less than 6 nm; and (D) an intensity ratio (I(002)/I(101)) of the crystal plane (002) to the crystal plane (101) obtained by XRD analysis being less than 60; performing an alkaline activation on the initial soft carbon material with an alkaline activator to obtain a first processing carbon material; and performing an electrochemical activation on the first processing carbon material with an electrolyte to obtain the soft carbon material for the high-voltage supercapacitors.