Core-Shell Sodium Cathode Precursor for Capacity and Cycle Stability
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Solution Overview
Problem
Sodium-ion batteries face challenges in achieving high cycling stability and specific capacity due to the instability of their positive electrode materials, particularly the P2 and O3 phases, which are difficult to combine effectively for large-scale industrial application.
Innovation Solution
A positive electrode material precursor with a heterogeneous structure of an O3-phase core and a P2-phase shell is developed, where the core and shell are composed of flaky primary particles, allowing for improved sodium ion diffusion and stability, achieved through a controlled co-precipitation process and calcination method suitable for large-scale production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If P2-phase positive electrode material is used, then structural stability is improved, but specific capacity is reduced
Solution Approach 1:
The patent applies composite materials by creating a heterostructure that combines P2-phase and O3-phase materials. The P2-phase provides structural stability while the O3-phase contributes high specific capacity, achieving a synergistic effect where the composite material exhibits both high stability and high capacity that neither phase could achieve alone.
2Quantity of substance
If O3-phase positive electrode material is used, then specific capacity is improved, but structural stability is reduced
Solution Approach 1:
The patent uses composite materials to combine O3-phase (high capacity) with P2-phase (high stability). The O3-phase delivers high specific capacity while the P2-phase provides structural stability, creating a composite that overcomes the limitations of using O3-phase alone.
Solution Approach 2:
The patent applies local quality by creating a heterostructure where different phases are distributed in specific configurations. The P2 and O3 phases are arranged to leverage their respective advantages locally, with each phase contributing its superior properties to the overall material performance.
3Manufacturing precision
If solvent evaporation method is used for coating, then coating quality is improved, but process complexity increases and environmental friendliness decreases
Solution Approach 1:
The patent replaces the thermal evaporation process with a chemical precipitation method. Instead of using heat to evaporate solvent and form the coating, the invention uses controlled chemical reactions to precipitate the coating material directly, eliminating the need for complex evaporation equipment and reducing energy consumption.
Solution Approach 2:
The patent introduces an intermediary chemical approach using precipitation reactions. Rather than directly evaporating solvent, the coating is formed through intermediate chemical species that precipitate the desired coating material, providing a gentler and more controllable process.
4Manufacturing precision
If sol-gel method is used for doping, then doping precision is improved, but scalability is reduced
Solution Approach 1:
The patent replaces the sol-gel method with a precipitation-based approach. The new method uses simple precipitation reactions that can be easily scaled up for industrial production while maintaining precise doping control through stoichiometric calculations and controlled addition rates.
Solution Approach 2:
The patent changes the fundamental parameter of the doping process from sol-gel chemistry to precipitation chemistry. This parameter change enables the process to be scaled up for industrial production while maintaining the precision needed for controlled doping, as precipitation reactions are more amenable to large-scale operation.
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
This approach enhances both the specific capacity and cycling stability of sodium-ion batteries, improving their electrochemical performance and making them more suitable for industrialization.
Implementation Method 1
A positive electrode material precursor with a heterogeneous structure of an O3-phase core and a P2-phase shell is developed, where the core and shell are composed of flaky primary particles, allowing for improved sodium ion diffusion and stability, achieved through a controlled co-precipitation process and calcination method
Implementation Method 2
achieved through a controlled co-precipitation process and calcination method suitable for large-scale production
Data Source
AI summary
Disclosed in the present disclosure are a positive electrode material precursor and a positive electrode material and preparation methods therefor, and a sodium-ion battery. The positive electrode material precursor comprises an inner core and a shell wrapping the periphery of the inner core, wherein the inner core is NixFeyMn1-x-y(OH)2, where 0.2≤x≤0.7, and 0.2≤y≤0.5; the shell is MaMn1-a(OH)2, where M is nickel or iron, and 0.05≤a≤0.7; and both the inner core and the shell are formed by stacking flaky primary particles. In the positive electrode material precursor provided in the present application, by controlling the components of the inner core and the shell and using a loose structure thereof formed by stacking flaky primary particles in combination, a heterostructure positive electrode material with an 03-phase inner core and a P2-phase shell can be obtained; and due to the synergistic effect of the two-phase structure, the heterostructure positive electrode material has both high capacity and high cycle stability, such that the electrochemical performance of a sodium-ion battery can be further improved. In addition, the preparation method for a positive electrode material provided in the present application is simple, has a relatively low cost, and is suitable for industrial large-scale production.