Cathode material and preparation method thereof and sodium ion battery
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Solution Overview
Problem
Prussian Blue cathode materials for sodium-ion batteries suffer from hygroscopicity, leading to poor processability and storage performance due to the presence of vacancy defects and crystalline water.
Innovation Solution
A cathode material is developed by coating a Prussian Blue substrate with a tannic acid polymer layer and a hydrophobic layer, such as hexadecylamine, to suppress hygroscopicity without affecting electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Prussian Blue is prepared by simple chemical precipitation method, then it is easy to prepare and low cost, but vacancy defects and crystalline water are present in the material structure
Solution Approach 1:
The patent applies preliminary action by performing high-temperature heat treatment (calcination at 400-600°C for 2-24 hours) on the Prussian Blue precursor before battery assembly to remove crystalline water and reduce vacancy defects. This pre-treatment step addresses the structural quality issues before the material is used in battery manufacturing processes.
2Stability of the object's composition
If high-temperature heat treatment is applied to remove crystalline water, then dehydrated Prussian Blue is obtained, but it rapidly reabsorbs water due to strong hygroscopic nature when exposed to air
Solution Approach 1:
The patent applies preliminary anti-action by conducting all subsequent battery manufacturing processes (pulping, coating, rolling, slicing, winding/laminating, liquid injection, formation) under inert atmosphere (argon or nitrogen) immediately after heat treatment. This prevents the dehydrated Prussian Blue from reabsorbing water during processing by creating a protective atmosphere barrier.
Solution Approach 2:
The patent uses inert atmosphere (argon or nitrogen) throughout the battery manufacturing process to prevent water reabsorption. The inert gas displaces moisture in the air, creating a non-hygroscopic environment that maintains the dehydrated state of Prussian Blue during all handling and processing steps.
3Productivity
If Prussian Blue undergoes multiple manufacturing processes exposed to air, then battery production is completed, but hygroscopic nature leads to poor processability and absorbed moisture impacts sodium storage performance and battery safety
Solution Approach 1:
The patent implements inert atmosphere (argon or nitrogen) for all battery manufacturing processes including pulping, coating, rolling, slicing, winding/laminating, liquid injection, and formation. This continuous inert environment prevents moisture absorption during the entire production sequence, maintaining both processability and final battery performance.
Solution Approach 2:
The inert atmosphere acts as an intermediary medium between the dehydrated Prussian Blue and the external environment. This intermediary layer of argon or nitrogen gas prevents direct contact between the hygroscopic material and atmospheric moisture, enabling successful completion of all manufacturing steps without water reabsorption.
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 double-layer coated cathode material effectively inhibits hygroscopicity, improving storage stability and electrochemical performance in air, and maintaining excellent cycling and rate performance in sodium-ion batteries.
Implementation Method 1
a second coating layer successively coating a surface of the first coating layer, wherein a material forming the first coating layer includes a polymer of tannic acid; and a material forming the second coating layer includes at least one of hexadecylamine, octadecylamine, octadecyl phosphate, N-phenyl-bis(trifluoromethanesulfonimide), 1H,1H,2H,2H-perfluorodecyl triethoxysilane, and 1H,1H,2H,2H-perfluorodecanethiol
Data Source
AI summary
The present disclosure relates to the field of sodium ion battery technology, in particular, to a cathode material, a preparation method thereof, and a sodium ion battery. The present disclosure relates to a cathode material including a Prussian Blue substrate, and a first coating layer and a second coating layer successively coated on the surface of the Prussian Blue substrate; a material forming the first coating includes a polymer of tannic acid; a material forming the second coating layer includes at least one of hexadecylamine, octadecylamine, octadecyl phosphate, N-phenyl-bis(trifluoromethanesulfonimide), 1H,1H,2H,2H-perfluorodecyl triethoxysilane, and 1H,1H,2H,2H-perfluorodecanethiol. The cathode material of the present disclosure effectively solves the problem of hygroscopicity of Prussian Blue cathode material and effectively improves the storage property and electrochemical performance of the cathode material in air.