Prussian White Cathode Particle Control for Moisture Stability
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Solution Overview
Problem
Prussian white cathode materials in sodium ion batteries suffer from moisture-driven degradation and capacity fading due to Na-loss, which affects their electrochemical performance and stability.
Innovation Solution
A sodium iron(II)-hexacyanoferrate(II) material with controlled particle diameter (4 μm to 50 μm) and BET specific surface area (0.1 m2/g to 10 m2/g) is prepared to enhance moisture stability and reduce Na-loss, using a method involving acid decomposition and controlled drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Prussian white cathode material is used in sodium ion batteries, then high capacity is achieved, but moisture-driven degradation and capacity fading occur due to Na-loss
Solution Approach 1:
The patent applies parameter changes by controlling the particle size distribution (D50 between 4-50 μm) and BET specific surface area (0.1-10 m2/g) of the Prussian white material. These parameter optimizations reduce the material's susceptibility to moisture-driven degradation while maintaining high capacity, directly resolving the contradiction between capacity and moisture stability.
2Ease of manufacture
If water is present in the Prussian white structure, then material formation is easier, but electrochemical potential and cycling stability are negatively affected
Solution Approach 1:
The patent controls the water content parameter in the Prussian white structure to an optimized range, achieving a balance between ease of material formation and cycling stability. By precisely controlling this parameter, the patent maintains manufacturability while significantly improving electrochemical performance and cycling stability.
3Ease of operation
If airborne moisture exposure occurs, then material is easier to handle, but Na-loss from Prussian white structure increases leading to limited practical capacity
Solution Approach 1:
The patent optimizes the particle size and surface area parameters to reduce the material's reactivity toward airborne moisture. This parameter optimization allows easier handling while minimizing Na-loss and preserving practical capacity, resolving the contradiction between ease of operation and capacity retention.
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 optimized sodium iron(II)-hexacyanoferrate(II) material exhibits improved moisture stability and reduced capacity fading, maintaining high conductivity and sodium retention.
Implementation Method 1
acid decomposition of Na4Fe(CN)5*10H2O in an acid wherein the H+ to Fe ratio is within the range of from 7:1 to 1:1 and the temperature is within the range of from 50° C. to 120° C. during a period of time within the range of from 0.1 hour to 30 hours
Implementation Method 2
separating and drying the obtained powder
Data Source
AI summary
Described is a sodium iron (II)-hexacyanoferrate (II) material, wherein the particles of the sodium iron (II)-hexacyanoferrate (II) material have a particle diameter D50 value within the range of from 4 μm to 50 μm and a BET specific surface area within the range of from 0.1 m2/g to 10 m2/g.