Self-Supporting Porous Carbon Structure for Air Battery Cathodes
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Solution Overview
Problem
Current air batteries face challenges in achieving a small size, light weight, and high capacity due to insufficient air or oxygen permeability, ion transport efficiency, and reaction field in their positive electrode structures, particularly because existing porous carbon materials are not self-supporting and have pore volumes reduced by binders during electrode layer formation.
Innovation Solution
A porous carbon structure with specific conditions, including a t-plot external specific surface area of 900-1600 m^2/g, pore volumes of 2.2-7 cm^3/g for pores 1-200 nm and 4.0-10 cm^3/g for pores 1-1000 nm, overall porosity of 92-99%, and self-supporting ability, manufactured using a method involving a mixture slurry with carbon fibers and a binding polymer, carbonization in an oxidizing gas atmosphere, and subsequent inert gas treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If porous carbon materials are used to increase air permeability, then air or oxygen permeability is improved, but the materials are not self-supporting and require binders and current collectors, increasing weight and complexity
Solution Approach 1:
The porous carbon material itself forms a self-supporting structure that does not require external binders or current collectors. The carbon particles aggregate to form a mechanically stable porous network that can support itself, eliminating the need for additional supporting components and reducing overall weight.
Solution Approach 2:
The invention uses composite porous carbon materials formed by aggregating carbon particles with specific surface areas (50-200 m²/g) to create a self-supporting structure. This composite approach allows the material to achieve both high porosity for air permeability and mechanical strength for self-supporting capability without requiring separate binder or current collector layers.
2Strength
If binders are used to form electrode layers, then structural integrity is improved, but pore volume is reduced and air permeability deteriorates
Solution Approach 1:
The invention extracts and eliminates the binder component from the electrode structure. By using self-supporting porous carbon aggregates, the patent removes the binder that would otherwise block pores and reduce air permeability, while maintaining structural integrity through the self-supporting nature of the carbon aggregate structure.
3Strength
If current collectors are used to support the positive electrode, then mechanical strength is improved, but weight increases and battery size increases
Solution Approach 1:
The porous carbon aggregate structure serves its own mechanical support function without requiring a separate current collector. The self-supporting capability of the carbon aggregate network eliminates the need for additional current collector layers, reducing both weight and overall battery size while maintaining mechanical strength.
4Object-affected harmful factors
If the positive electrode structure is made porous to increase air permeability, then air or oxygen permeability is improved, but ion transport efficiency and reaction field are reduced
Solution Approach 1:
The invention creates local quality variations within the porous structure by using carbon particles with specific surface areas of 50-200 m²/g that aggregate to form a hierarchical pore structure. This local structural optimization ensures that pores are distributed and sized appropriately to maintain both high air permeability and efficient ion transport pathways throughout the electrode.
Solution Approach 2:
The patent utilizes porous carbon aggregate materials with controlled pore structures formed by aggregating carbon particles with specific surface areas of 50-200 m²/g. This porous structure is designed to simultaneously provide high air permeability for oxygen supply and maintain adequate ion transport efficiency by creating interconnected pore networks that facilitate both gas and ion movement.
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 porous carbon structure enables a battery with high air or oxygen permeability, ion transport efficiency, and a wide reaction field, allowing for a compact, high-capacity air battery without the need for a current collector, reducing weight and size while maintaining mechanical strength.
Implementation Method 1
the porous carbon structure is required to have high air or oxygen permeability
Implementation Method 2
the positive electrode structure is required to have both high ion transport efficiency and a wide reaction field
Implementation Method 3
carbonization in an oxidizing gas atmosphere
Data Source
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AI summary
The present invention addresses the problem of providing: a porous carbon structure that has a high micropore volume and can be self-contained; a manufacturing method therefor; a positive electrode material using the same; and a battery (particularly an air battery) using the same. The present invention is a porous carbon structure that is for a positive electrode for an air battery and has voids and a skeleton formed by incorporating carbon, the porous carbon structure satisfying all of the following conditions (a) to (d). (a) The t-plot external specific surface area is within the range of 300m2/g to 1600m2/g; (b) the total volume of micropores having a diameter of 1nm to 200nm is within the range of 1.2cm3/g to 7.0cm3/g; (c) the total volume of micropores having a diameter of 1nm to 1000nm is within the range of 2.3cm3/g to 10.0cm3/g; and (d) the overall porosity is within the range of 80% to 99%.