High-Nickel Sodium-Ion Cathode Coating Against Surface Passivation
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Solution Overview
Problem
Current high-nickel sodium ion batteries face issues with sodium ion diffusion due to disordering effects and rapid reaction with environmental gases, leading to poor electrochemical performance and limited application potential.
Innovation Solution
A high-nickel sodium ion cathode material with the chemical formula NaNiaCobMncO2·fCNP—Al/tMVOx, where MVOx is vanadate-based, and a preparation method involving recycling of waste lithium battery materials, calcination processes, and a sodium salt coating to enhance conductivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-nickel cathode material is used to achieve high capacity, then specific capacity is improved, but cation disordering occurs which reduces sodium ion diffusion rate
Solution Approach 1:
A coating layer comprising aluminum oxide, aluminum hydroxide, and carbon is formed on the surface of the high-nickel cathode material particles. This thin film coating prevents cation disordering and maintains structural integrity, thereby preserving high specific capacity while enabling sustained sodium ion diffusion rates throughout charge-discharge cycles.
Solution Approach 2:
The cathode material employs a composite structure combining high-nickelNaNi0.8Co0.05Mn0.15O2 with a multi-component coating layer of aluminum oxide, aluminum hydroxide, and carbon. This composite approach leverages the high capacity of nickel-rich material while the coating components work synergistically to prevent cation disordering and maintain ion diffusion pathways.
2Quantity of substance
If high-nickel cathode material is sintered and cooled to achieve high capacity, then specific capacity is improved, but the material reacts with environmental H2O and CO2 to form passivation layer
Solution Approach 1:
The cathode material is sintered and cooled in an inert atmosphere to prevent reaction with environmental H2O and CO2. The resulting coating layer of aluminum oxide, aluminum hydroxide, and carbon further acts as a protective barrier, isolating the high-nickel material from environmental moisture and carbon dioxide, thereby preventing formation of harmful passivation layers and maintaining electrochemical performance stability.
3Stability of the object's composition
If passivation layer forms on cathode surface to protect material, then material stability is improved, but sodium ion diffusion at interface is hindered and impedance increases
Solution Approach 1:
A carefully engineered thin film coating layer comprising aluminum oxide, aluminum hydroxide, and carbon is formed on the cathode material surface. This coating is sufficiently thin to allow efficient sodium ion diffusion while providing protective functions. The aluminum-based compounds offer stability without creating excessive impedance, unlike thick passivation layers of Na2CO3 and NaOH.
Solution Approach 2:
The coating layer composition and thickness are precisely controlled to optimize the balance between protection and ion transport. By adjusting the ratios of aluminum oxide, aluminum hydroxide, and carbon, and controlling coating thickness, the material achieves both stability and high sodium ion diffusion rate, avoiding the impedance increase associated with conventional passivation layers.
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 solution improves sodium ion diffusion, structural stability, and electrochemical performance, increasing specific capacity and cycle stability, while also promoting environmental sustainability by recycling materials.
Implementation Method 1
The mixture is subjected to drying and dewatering, first-stage calcination, and annealing
Implementation Method 2
CNP—Al is prepared by mixing the carbon nano powder with the dispersing agent, then with the aluminum source, and then treating the mixture at 900° C. to 1,300° C. for 3 hours to 12 hours under a protective atmosphere
Implementation Method 3
CNP—Al contains Al4C3
Implementation Method 4
the high-nickel sodium ion cathode material in the battery responses quickly to an external environment in contact, easily reacts with H2O and CO2 in the environment to generate Na2CO3 and NaOH
Implementation Method 5
NaOH is dehydrated to form Na2O
Data Source
AI summary
Disclosed are a high-nickel sodium ion cathode material and a preparation method therefor and a battery, wherein a chemical formula of the high-nickel sodium ion cathode material is NaNiaCobMncO2·fCNP—Al/tMVOx, wherein a+b+c=1, 0.5≤a<1, 0<b≤0.25, a/b≥2.5, 0<c≤0.3, 0<t≤0.1, 0<f≤0.1, and M is at least one of sodium, copper, zinc, zirconium or ammonium.