Fe-Substituted Mn Prussian Blue Analogue for Vacancy Control
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Solution Overview
Problem
Existing methods for synthesizing transition metal cyanide coordination compounds (TMCCC) for use in electrochemical cells, such as sodium ion secondary batteries, are inefficient and result in materials with lower energy density due to high vacancy concentrations and the use of toxic reagents.
Innovation Solution
A novel synthesis method for TMCCC materials is developed, which includes the use of bifunctional compounds like ethylene glycol and sulfur-containing reducing agents to suppress vacancy formation, resulting in materials with improved specific capacity and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If acid decomposition of sodium hexacyanoferrate is used to suppress vacancy formation, then specific capacity is improved, but deintercalation/intercalation potential decreases and energy density is reduced
Solution Approach 1:
The patent changes the chemical composition parameters by introducing Fe-substituted Mn-based prussian blue analogue with specific stoichiometry (Na0.9Mn5.7Fe0.3(CN)6) to achieve optimal vacancy concentration while maintaining high deintercalation/intercalation potential, thus resolving the contradiction between vacancy control and energy density
Solution Approach 2:
The patent creates a composite material system by substituting Fe into Mn-based prussian blue analogue structure, forming a new compound that combines the benefits of both metals to achieve low vacancy concentration and high energy density simultaneously
2Manufacturing precision
If excess alkali ion and chelating agents are used to suppress vacancy formation, then specific capacity is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the need for excess alkali ions and chelating agents from the synthesis process by using a stoichiometrically balanced Fe-substituted Mn-based prussian blue analogue composition, thereby simplifying the manufacturing process while maintaining low vacancy concentration
Solution Approach 2:
The patent optimizes the compositional parameters of the prussian blue analogue by precisely controlling the Fe substitution ratio in Mn-based structure, achieving vacancy suppression through composition optimization rather than process complexity
3Manufacturing precision
If acid hydrolysis of sodium hexacyanoferrate is used, then specific capacity is improved, but production time increases and toxic HCN waste is generated
Solution Approach 1:
The patent converts the harmful acid hydrolysis process into a beneficial direct synthesis approach by using Fe-substituted Mn-based prussian blue analogue that forms with low vacancy concentration through controlled precipitation, eliminating toxic HCN waste and reducing synthesis time while maintaining high specific capacity
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 new synthesis method effectively reduces vacancy concentrations in TMCCC materials, enhancing their specific capacity and energy density, while also being more environmentally friendly and scalable for industrial production.
Implementation Method 1
sulfur-containing reducing agents to suppress vacancy formation
Data Source
AI summary
A system and method implementing and manufacturing transition metal cyanide coordination compounds (TMCCC) comprising Na, Fe, Mn, C, H, N, S, and O, wherein the TMCCC have 0-14% hexacyanometallate vacancies such as for application in electrochemical cells, including sodium ion secondary batteries; further including both sodium and potassium with and without sulfate.