Coated Sodium-Ion Cathode Material for Phase-Stable Cycling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Cathode materials for sodium ion batteries experience lattice distortion and phase changes during charging and discharging, hindering sodium ion transport and diffusion, leading to irreversible capacity loss and performance degradation.
Innovation Solution
A cathode material with a chemical formula Na1+aNixMnyFezAmBnO2, where A and B elements are modified to enhance structural stability and form a protective coating, facilitating sodium ion transport and reducing side reactions with the electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If layered oxide structure is used for high specific capacity and high voltage, then cathode material performance is improved, but lattice distortion and phase transformation occur during charge-discharge, hindering sodium ion transport and causing irreversible capacity loss
Solution Approach 1:
The patent applies local quality by introducing different elements (A and B elements) at specific positions in the crystal structure. A elements are incorporated into the transition metal layer to stabilize the layered structure and prevent Jahn-Teller distortion, while B elements form a coating layer on the particle surface to protect against electrolyte degradation. This localized modification approach maintains high capacity while improving cycling stability.
Solution Approach 2:
The patent creates a composite cathode material with a core-shell structure. The core consists of the layered oxide with high specific capacity, while the shell is formed by B element coating that provides structural stability and protects against side reactions. This composite structure combines the advantages of high capacity with improved cycling performance and reduced irreversible capacity loss.
2Ease of manufacture
If excessive sodium salt is added during preparation to compensate for sodium loss, then material production is simplified, but free sodium residue increases causing high alkalinity, moisture absorption, and poor processing performance
Solution Approach 1:
The patent optimizes the sodium salt addition parameter by precisely controlling the molar ratio of sodium source to transition metal sources. Instead of adding excessive sodium salt, the method adjusts the sodium content to achieve complete sodium ion occupation in the layered structure without free sodium residue. This parameter optimization eliminates the need for post-treatment while improving processing performance and reducing moisture absorption.
3Reliability
If surface coating is applied to inhibit side reactions and improve cycling performance, then irreversible capacity loss is reduced, but material structure complexity increases
Solution Approach 1:
The patent employs a thin film coating approach where B element forms a uniform, thin protective layer on the cathode material surface. This thin film structure effectively inhibits side reactions between the cathode material and electrolyte, reducing irreversible capacity loss and improving cycling performance, while adding minimal structural complexity compared to thick or multi-layer coatings.
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 modified cathode material improves sodium ion diffusion and cycling performance by stabilizing the structure and forming a protective layer, reducing irreversible capacity loss and enhancing battery stability.
Implementation Method 1
the surface of the material is modified by coating the material, thereby forming an effective protective layer on the surface of the material, inhibiting side reactions between the material and the electrolyte
Implementation Method 2
lattice distortion and phase transformation during the charge and discharge of sodium ions, which hinders the transport and diffusion of sodium ions
Data Source
AI summary
A cathode material for a sodium ion battery having a coating structure having chemical formula: Na1+aNixMnyFezAmBnO2, where −0.35≤a≤0.20, 0.08<x≤0.5, 0.05<y≤0.48, 0.03<z<0.4, 0.03<m<0.24, 0.001<n<0.06, x+y+z+m+n=1. A preparation method of a cathode material for a sodium ion battery comprises the steps of: firstly, mixing a sodium source, a nickel source, a manganese source, an iron source and an A source uniformly, and then performing a first sintering, cooling and crushing to obtain a semi-finished product; then, after mixing the semi-finished product with a B source uniformly, performing a second sintering, cooling and crushing to obtain the cathode material for a sodium ion battery. The cathode material for a sodium ion battery according to the present disclosure is structurally stable, and a surface coating layer thereof inhibits side reactions with an electrolyte, so that the cycling performance is significantly improved.