Ferrite Spinel Thin-Film Coatings for Solar Redox Energy Storage
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Solution Overview
Problem
Current solar energy storage methods, such as high heat transfer storage mediums like molten salt and silica, face challenges including large mass requirements, heat loss during handling, and limited energy storage capacity due to substoichiometric reduction in ferrite spinel materials, which restricts efficient energy storage and release.
Innovation Solution
A substrate with a 1-100 nm thick metal ferrite spinel coating, applied via atomic layer deposition, that is thermally and oxidatively stable up to 900°C, allowing for stoichiometric reduction at lower temperatures, enabling efficient energy storage and release through redox reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If substoichiometric reduction of ferrite spinel is used, then energy storage capacity is improved, but material reactivity decreases over multiple cycles
Solution Approach 1:
The patent changes the reduction parameter from substoichiometric to stoichiometric reduction, allowing complete oxygen removal while maintaining material stability. This enables full energy storage capacity (one oxygen atom per formula unit) while preserving reactivity for multiple cycles, resolving the contradiction between storage capacity and reliability
Solution Approach 2:
The patent uses composite ferrite spinel materials with specific metal compositions (Mn, Ni, Co, Cu, or Zn) that enable both complete reduction and stable reoxidation. The composite structure allows stoichiometric reduction while maintaining material integrity and reactivity over multiple cycles
2Stability of the object's composition
If high temperatures (1750-1800 K) are used for zinc ferrite spinel reduction, then complete reduction is achieved, but zinc vaporizes and separates from iron
Solution Approach 1:
The patent lowers the reduction temperature from 1750-1800 K to below 1750 K, which prevents zinc vaporization while still achieving complete stoichiometric reduction. This temperature parameter change resolves the contradiction between complete reduction and zinc stability
Solution Approach 2:
The patent employs thin film coatings (1-100 nm) of ferrite spinel on substrate particles, which provide high surface area to volume ratio for efficient reduction and reoxidation while maintaining material stability at lower temperatures, preventing zinc loss
3Quantity of substance
If large masses of storage medium are used, then energy storage capacity is improved, but heat loss through walls and handling equipment increases
Solution Approach 1:
The patent uses thin film coatings (1-100 nm) of ferrite spinel on substrate particles, which provide extremely high surface area to volume ratio. This allows small masses of storage material to achieve high energy storage capacity while minimizing heat loss through walls and handling equipment
Solution Approach 2:
The substrate particles provide porous structures that increase surface area for the ferrite spinel coating, enabling high energy storage capacity in small volumes with reduced heat loss
4Duration of action of moving object
If hot storage medium is stored for extended periods, then energy availability is improved, but the medium cools to temperatures too low for efficient use
Solution Approach 1:
The ferrite spinel material stores energy through reversible redox reactions, maintaining chemical stability at storage temperatures. The material can be stored in an inert atmosphere at ambient or elevated temperatures without continuous heating, and remains ready for rapid reoxidation when needed, providing extended energy availability without excessive cooling
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 coated substrate efficiently captures and stores solar energy, allowing for its release during periods of low sunlight, with improved energy storage capacity and reduced heat loss, using a wider range of support materials and lower manufacturing costs.
Implementation Method 1
Certain ferrite spinel materials are capable of engaging in redox reactions, in which the materials are partially or fully reduced and then re-oxidized. The reduction step can be performed thermally by heating the ferrite spinel to high temperature. The oxidation step can be performed by exposing the reduced ferrite spinel to water or oxygen.
Implementation Method 2
the coating is applied via atomic layer deposition
Data Source
AI summary
1-100 nm metal ferrite spinel coatings are provided on substrates, preferably by using an atomic layer deposition process. The coatings are able to store energy such as solar energy, and to release that stored energy, via a redox reaction. The coating is first thermally or chemically reduced. The reduced coating is then oxidized in a second step to release energy and/or hydrogen, carbon monoxide or other reduced species.