Carbon-Coated Prussian White Cathode Without Crystal Water
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Solution Overview
Problem
Current Prussian white materials used in sodium-ion batteries suffer from poor electrical conductivity, thermal stability, and are often contaminated with crystal water, leading to reduced cycle life and energy density.
Innovation Solution
A Prussian white composite material is developed, comprising an inner core with a specific chemical formula and a carbon coating layer, which enhances electrical conductivity and thermal stability while eliminating crystal water. The material is synthesized through a hydrothermal method followed by ion exchange and carbon coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Prussian white materials are synthesized in aqueous phase with crystal water, then the synthesis process is simple, but the thermal stability and electrical conductivity are poor
Solution Approach 1:
The patent changes the synthesis phase from aqueous to non-aqueous (organic solvent), which fundamentally alters the product properties by eliminating crystal water formation. This parameter change resolves the contradiction by maintaining ease of manufacture through simple solvent replacement while dramatically improving thermal stability and electrical conductivity.
Solution Approach 2:
The patent creates a composite structure by coating the Prussian white particles with carbon material. This composite approach maintains the simple synthesis process while the carbon coating layer provides enhanced electrical conductivity and thermal stability, resolving the contradiction between manufacturing simplicity and material performance.
2Ease of manufacture
If Prussian white materials are synthesized in aqueous phase with crystal water, then the synthesis process is simple, but the electrical conductivity is poor
Solution Approach 1:
The patent changes the synthesis phase from aqueous to non-aqueous (organic solvent), which fundamentally alters the product properties by eliminating crystal water formation. This parameter change resolves the contradiction by maintaining ease of manufacture through simple solvent replacement while dramatically improving electrical conductivity.
Solution Approach 2:
The patent creates a composite structure by coating the Prussian white particles with carbon material. This composite approach maintains the simple synthesis process while the carbon coating layer provides enhanced electrical conductivity, resolving the contradiction between manufacturing simplicity and electrical performance.
3Reliability
If crystal water is removed by baking at high temperature and high vacuum, then the crystal water content is reduced, but the energy consumption increases and microstructure is destroyed
Solution Approach 1:
The patent performs preliminary action by synthesizing the Prussian white material directly in a non-aqueous phase from the beginning, preventing crystal water formation during synthesis. This eliminates the need for subsequent high-temperature vacuum baking to remove crystal water, thereby resolving the contradiction by avoiding high energy consumption while achieving complete crystal water removal.
4Reliability
If crystal water is removed by baking at high temperature and high vacuum, then the crystal water content is reduced, but the microstructure is destroyed
Solution Approach 1:
The patent performs preliminary action by synthesizing the Prussian white material directly in a non-aqueous phase from the beginning, preventing crystal water formation during synthesis. This eliminates the need for subsequent high-temperature vacuum baking, thereby resolving the contradiction by avoiding microstructure destruction while achieving complete crystal water removal.
5Ease of manufacture
If Prussian white materials contain crystal water, then the synthesis is easier, but the cycle life is reduced
Solution Approach 1:
The patent changes the synthesis phase from aqueous to non-aqueous (organic solvent), which fundamentally alters the product properties by eliminating crystal water formation. This parameter change resolves the contradiction by maintaining synthesis ease through simple solvent replacement while dramatically improving cycle life.
Solution Approach 2:
The patent creates a composite structure by coating the Prussian white particles with carbon material. This composite approach maintains easy synthesis while the carbon coating provides enhanced cycle life by preventing electrolyte corrosion and maintaining structural integrity, resolving the contradiction between synthesis ease and cycle life.
6Ease of manufacture
If Prussian white materials contain crystal water, then the synthesis is easier, but the volumetric energy density is reduced
Solution Approach 1:
The patent changes the synthesis phase from aqueous to non-aqueous (organic solvent), which fundamentally alters the product properties by eliminating crystal water formation. This parameter change resolves the contradiction by maintaining synthesis ease through simple solvent replacement while increasing volumetric energy density by removing water content.
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 resulting Prussian white composite material exhibits improved electrical conductivity, thermal stability, and cycle life, with a capacity retention rate of 88% or higher after 100 cycles, making it suitable for high-performance sodium-ion batteries.
Implementation Method 1
a potassium-based Prussian white material is obtained, and then the potassium-based Prussian white material is subjected to ion exchange to obtain a sodium-based Prussian white material
Implementation Method 2
the sodium-based Prussian white material is subjected to carbon coating to obtain a Prussian white composite material
Implementation Method 3
a soluble divalent manganese salt, a soluble divalent salt containing an M element and potassium citrate are mixed with a solvent to obtain a solution A; adding a potassium ferrocyanide solution to the solution A for mixing, and carrying out a precipitation reaction
Data Source
AI summary
A Prussian white composite material. The Prussian white composite material includes an inner core and a carbon coating layer that coats at least a portion of an outer surface of the inner core, where the inner core has a general formula of NaxMn1-yMy[Fe(CN)6]z, in the formula, M is selected from at least one of Fe, Co, Ni, Cu and Zn, x is greater than 1.5 and equal to or less than 2, y is greater than 0 and equal to or less than 0.3, and z is greater than 0.8 and equal to or less than 1. The Prussian white composite material of the present invention is free of crystal water (including interstitial water and coordinated water), has complete crystal lattices and good ionic conductivity and thermal stability, and is hardly decomposed at 500° C. A preparation method has the advantages of being simple in process, low in cost, short in period, low in energy consumption, suitable for industrial production and the like.