Copper-Based Sodium Layered Oxide Composition for Air-Stable Cathodes
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Solution Overview
Problem
Sodium ion layered oxide positive electrode materials are unstable in air, leading to significant sodium loss, which affects the performance and production costs of sodium ion batteries, hindering their industrialization.
Innovation Solution
Regulate the weighted average ionic potential and particle size of primary particles in copper-based sodium ion layered oxide materials to enhance air stability, using methods such as adjusting stoichiometric ratios, sintering temperature, and adding sodium fluxes to reduce sodium loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If layered oxide Na x MO 2 is used as positive electrode material, then high capacity and high tap density are achieved, but air stability deteriorates and sodium loss increases
Solution Approach 1:
The patent changes the chemical composition parameters by introducing copper ions and adjusting the stoichiometric ratios of metal elements. This modifies the weighted average ionic potential of cations to fall within 45-55 nm⁻¹, which fundamentally alters the material's chemical stability parameters without sacrificing its electrochemical capacity
Solution Approach 2:
The patent creates a composite layered oxide structure with multiple metal elements (Cu, Ni, Mn, Co, etc.) in specific ratios. This composite approach combines the high capacity characteristics of different metals while achieving synergistic effects that improve overall air stability and reduce sodium loss
2Ease of manufacture
If conventional layered oxide material is used, then easy preparation and large-scale production are achieved, but sodium loss in humid air exceeds 30% after 48 hours
Solution Approach 1:
The patent optimizes sintering parameters including temperature (900-1100°C), time (10-20 hours), and atmosphere control. These parameter changes enhance the material's resistance to sodium loss while maintaining compatibility with conventional preparation methods for ease of manufacturing
Solution Approach 2:
The patent performs preliminary optimization of the material composition before the actual battery assembly process. By pre-adjusting the ionic potential and particle size distribution, the material is prepared in advance to resist sodium loss during subsequent storage and operation in humid conditions
3Productivity
If particle size is reduced to increase surface area, then electrochemical activity improves, but air stability deteriorates and sodium loss increases
Solution Approach 1:
The patent optimizes particle size parameters to a specific range (3-10 μm) and controls particle size distribution. This parameter optimization balances the electrochemical activity benefits of smaller particles with the air stability advantages of larger particles, achieving both high productivity and reliability
Solution Approach 2:
The patent creates a protective surface structure on the particles that replicates stable crystal facets. This surface copying approach maintains high surface area for electrochemical activity while the replicated stable surfaces resist sodium loss and improve air stability
4Reliability
If weighted average ionic potential is increased to improve stability, then electrochemical potential increases, but manufacturing complexity increases
Solution Approach 1:
The patent establishes a specific target range for weighted average ionic potential (45-55 nm⁻¹) and provides clear calculation methods and composition guidelines. This parameter standardization simplifies the manufacturing process by giving concrete targets rather than requiring complex optimization, reducing manufacturing complexity while achieving high stability
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 method significantly reduces sodium loss, improves electrochemical stability, and enhances the material's resistance to humid air, making it suitable for large-scale production and application in sodium ion batteries.
Implementation Method 1
a majority of layered oxide positive electrode materials of the sodium ion battery are unstable in air, and is prone to sodium loss in humid air
Data Source
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AI summary
A method for improving air stability of a sodium ion layered oxide, a material, and a use. The method for improving air stability of a sodium ion layered oxide comprises: regulating the weighted average ionic potential ΦM of cations other than sodium ions of a copper-based sodium ion layered oxide positive electrode material NaxCuyMzO2 and regulating a particle size r of primary particles of a crystal, so that 47.5 nm-1≤ΦM≤ 50.5 nm-1 and 1.4 µm≤r≤100 µm,thereby reducing the amount of sodium loss of the sodium ion layered oxide positive electrode material after deterioration in air, and obtaining a sodium ion battery layered oxide positive electrode material having air stability, wherein M is selected from one or more of Ni2+, Zn2+, Mg2+, Fe3+, La3+, Lu3+, Sb3+, Mn4+, Ti4+, Zr4+, Sn4+, and Bi5+; and 0.9≤x≤1, and y+z=1.