Phosphonate and Arsonate MOF Electrodes for Stable Supercapacitors
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Solution Overview
Problem
Current electrode materials for electrochemical double layer capacitors and supercapacitors, such as activated carbon, have limited surface areas and poor conductivity, stability, and resistance to corrosion, which hinders their performance and applications, especially in high-temperature and chemical environments.
Innovation Solution
The use of metal organic frameworks (MOFs) with inorganic building units comprising metal atoms from group 1 to 12 and functional groups containing phosphorus, arsenic, antimony, silicon, selenium, and bismuth, specifically phosphonate and arsonate groups, which provide high surface areas, conductivity, and stability, making them suitable for electrochemical double layer capacitors and semiconductive applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If activated carbon is used as electrode material, then the device can be manufactured with current technology, but the surface area is limited between 500 to 1500 m2/g which restrains further development
Solution Approach 1:
The patent employs metal organic frameworks (MOFs) as porous electrode materials to achieve surface areas exceeding 7000 m2/g, dramatically surpassing activated carbon's 500-1500 m2/g limit. The porous structure of MOFs provides extensive surface area while maintaining structural integrity, directly resolving the surface area limitation of conventional activated carbon electrodes.
Solution Approach 2:
The invention uses composite MOF structures combining organic linkers with metal ions or clusters to create hybrid materials that exhibit both high surface area and enhanced electrical conductivity. This composite approach overcomes the single-material limitations of activated carbon by integrating the advantages of both organic and inorganic components.
2Area of stationary object
If traditional MOFs with carboxylate metal binding groups are used, then high surface area to mass ratios above 7000 m2/g can be achieved, but the materials exhibit lower resistance against high temperatures and corrosion
Solution Approach 1:
The patent modifies the chemical composition parameters of MOFs by replacing traditional carboxylate linkers with phosphonate and arsonate groups, which have stronger metal-binding capabilities. This parameter change enhances thermal and chemical stability while preserving the high surface area to mass ratio above 7000 m2/g, directly addressing the stability limitation of conventional MOFs.
Solution Approach 2:
The invention develops MOFs with improved stability to extend the service life of electrode materials, reducing the frequency of replacement. The enhanced thermal and corrosion resistance allows these materials to withstand harsh operating conditions for longer durations, moving away from short-lived electrode materials.
3Adaptability or versatility
If paddle wheel patterned carboxylate MOFs are used, then diverse applications can be achieved, but the large distances between polyaromatic linkers limit conductivity with respect to electron hoping mechanisms
Solution Approach 1:
The patent transitions from molecular inorganic building units (0D) to one-dimensional and two-dimensional inorganic building units in MOF structures. This dimensional change reduces the distance between polyaromatic linkers and creates continuous conductive pathways through the framework, significantly enhancing electrical conductivity while maintaining application versatility.
Solution Approach 2:
The invention segments the inorganic building units into extended one-dimensional and two-dimensional structures rather than isolated molecular units. This segmentation creates overlapping orbital networks that facilitate electron delocalization and hopping, improving electrical conductivity across the MOF framework while preserving the modular nature needed for diverse applications.
4Area of stationary object
If carboxylate MOFs are used as electrode materials, then high surface area can be provided, but they display comparably low chemical stability in presence of electrolytes, humidity, acidic medium and water
Solution Approach 1:
The patent converts the traditionally harmful effects of humidity, water, and acidic media into beneficial conditions by designing phosphonate and arsonate MOFs that are specifically stable under these conditions. The stronger metal-phosphonate and metal-arsonate bonds provide resistance against hydrolysis and acid dissolution, allowing the high surface area material to maintain stability in previously damaging environments.
Data Source
AI summary
An electrode suitable for constructing an electrochemical double layer capacitor and/or supercapacitor is provided that includes an electrode material a metal organic framework (MOF), wherein the MOF includes an inorganic building unit including metal atoms selected from group 1 to group 12 elements, and functional groups of organic linkers including oxygen (O) and one or more atoms selected from the group comprising phosphorus (P), arsenic (As), antimony (Sb), silicon (Si), selenium (Se) and bismuth (Bi). The functional groups of the organic linkers can include phosphonate, arsonate, phosphonic acid, phosphinic acid, arsonic acids and/or arsenic acids, monoester and/or diester forms thereof. Further, the metal atoms may be selected from zinc (Zn), cadmium (Cd), copper (Cu), cobalt (Co), nickel (Ni), gold (Au) and silver (Ag). The use of the MOF as a semiconductor in semiconductor applications, a semiconductive device, such as a photovoltaic cell, including the MOF are also provided.