Magnetic Field-Assisted Etching for Nano-Porous Silicon Hydrogen Storage
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Solution Overview
Problem
Current hydrogen storage technologies for fuel cells are inefficient, environmentally undesirable, and costly, particularly for portable applications, as they either produce greenhouse gases or require heavy, safety-hazardous cylinders or high-energy cryogenic storage.
Innovation Solution
The use of a magnetic field to enhance the formation of nano-porous silicon (npSi) by applying a Lorentz force during etching, allowing for increased surface area and efficiency in storing and retrieving elemental hydrogen, even on small silicon particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional electrochemical etching is used to produce porous silicon, then porous structure is formed, but the surface area is insufficient and pore size is too large for efficient hydrogen storage
Solution Approach 1:
The patent applies a magnetic field to the silicon substrate before and during the etching process to pre-position charge carriers (holes) at specific locations. This preliminary arrangement of charge carriers ensures that when etching occurs, pores form with precise control over size and distribution, ultimately achieving higher surface area with smaller, more numerous pores suitable for efficient hydrogen storage
Solution Approach 2:
The patent replaces conventional mechanical or purely chemical etching methods with a magnetic field-assisted etching process. By using magnetic fields to control charge carrier movement and distribution during etching, the process achieves superior control over pore size and surface area without relying solely on mechanical agitation or chemical concentration variations
2Productivity
If chemical etching is used to form porous silicon, then porosity is created, but the process is slow and inefficient for large-scale production
Solution Approach 1:
The patent substitutes conventional slow chemical etching with a magnetic field-enhanced etching process. The magnetic field accelerates charge carrier (hole) movement to the etching front, significantly increasing the etching rate while simultaneously improving pore uniformity through controlled charge carrier distribution. This enables fast, large-scale production of uniform porous silicon
Solution Approach 2:
The patent changes the physical parameters of the etching process by introducing magnetic field strength and orientation as controlling variables. By adjusting magnetic field parameters, the process achieves both high etching rates and uniform pore structures, resolving the contradiction between productivity and manufacturing precision
3Quantity of substance
If existing hydrogen storage methods are used, then hydrogen can be stored, but the systems are heavy, costly, or environmentally harmful
Solution Approach 1:
The patent produces porous silicon with optimized high surface area and controlled pore size specifically for hydrogen storage applications. The porous structure provides numerous sites for hydrogen adsorption and storage, achieving high hydrogen storage capacity while maintaining low system weight, as porous silicon itself is lightweight compared to metal hydrides or compressed gas systems
Solution Approach 2:
The patent creates a composite storage system combining porous silicon with appropriate surface treatments or coatings to enhance hydrogen storage capacity. This composite approach achieves high hydrogen storage capacity while keeping the system lightweight and cost-effective, avoiding the drawbacks of pure metal hydrides or cryogenic systems
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
This method enables the production of npSi with increased surface area and reduced pore size, improving hydrogen storage capacity and efficiency while being more practical for large-scale and portable applications.
Implementation Method 1
a magnetic field is applied to a substrate containing charge carriers... During etching, the charge carriers move relative to the substrate and the magnetic field... subject holes within the substrate to Lorentz forces during etching
Data Source
AI summary
Processes and apparatuses for producing a porous material, such as nano-porous silicon (npSi) media suitable for storage and retrieval of elemental hydrogen. Processes of this invention generally entail applying a magnetic field to a substrate that contains charge carriers and is in contact with an etchant, and then etching the substrate with the etchant while relative movement occurs between the substrate and the magnetic field. During etching, the charge carriers move relative to the substrate and the magnetic field, and porosity forms at surfaces of the substrate contacting the etchant.