Layered-Oxide Cathode Composition for Water-Stable Sodium-Ion Coating
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Solution Overview
Problem
Layered-oxide positive electrode active materials for sodium-ion batteries face challenges with low capacity, poor water stability, and difficult coating processes, making them unsuitable for commercial applications.
Innovation Solution
A layered-oxide positive electrode active material with finely adjusted percentages of doping elements such as Cu, Li, Ti, and non-metal elements like Si and F, combined with a molecular formula NaxMnaFebNicMdNeO2-δQf, achieves high capacity, high water stability, and easy coating, with a space group of R3m, and specific particle and density characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If layered-oxide positive electrode active materials are used for sodium-ion batteries, then high theoretical specific capacity and high density are achieved, but low capacity, poor water stability, and poor coating effect occur
Solution Approach 1:
The patent applies parameter changes by precisely controlling the doping amounts of multiple elements (M: 0.01-0.50 mol, N: 0.01-0.50 mol, Q: 0.01-0.50 mol) relative to the base metal elements (Mn: 0.20-0.60 mol, Fe: 0.10-0.40 mol, Ni: 0.05-0.25 mol). This systematic parameter optimization transforms the material properties to achieve both high capacity and excellent water stability, resolving the contradiction between theoretical potential and actual performance.
Solution Approach 2:
The patent creates a composite doped layered-oxide material by incorporating multiple dopant elements (M, N, Q) into the base structure (NaxMn1-a-b-c-d-eFeaNicNidMeeO2-δQf). This composite approach combines the benefits of different elements: M elements enhance capacity, N elements improve stability, and Q elements optimize coating properties, thereby resolving the individual limitations of simple layered-oxide structures.
2Quantity of substance
If layered-oxide positive electrode active materials are used for sodium-ion batteries, then high theoretical specific capacity and high density are achieved, but poor coating effect occurs
Solution Approach 1:
The patent improves coating effect by optimizing specific parameters including doping element concentrations (M: 0.01-0.50 mol, N: 0.01-0.50 mol, Q: 0.01-0.50 mol), particle size (5 μm to 50 μm), and surface morphology control through controlled atmosphere sintering. These parameter adjustments ensure uniform slurry formation and effective coating on current collectors, resolving the poor coating effect while maintaining high capacity.
3Device complexity
If conventional layered-oxide materials are used, then simple structure is maintained, but low capacity and poor performance occur
Solution Approach 1:
The patent maintains structural simplicity by using a single-phase doped layered-oxide composition (NaxMn1-a-b-c-d-eFeaNicNidMeeO2-δQf) rather than complex multi-component systems. The composite doping strategy enhances capacity within the simple layered structure, achieving high capacity (above 120 mAh/g) without complicating the fundamental material architecture.
Solution Approach 2:
The patent applies local quality by introducing dopant elements at specific lattice positions within the layered structure. The dopants M, N, and Q are incorporated into specific crystallographic sites, creating local structural modifications that enhance overall capacity while preserving the global simplicity of the layered-oxide framework.
Data Source
AI summary
A layered-oxide positive electrode active material may have a molecular formula of NaxMnaFebNicMdNeO2-δQf, where a doping element M is selected from at least one of Cu, Li, Ti, Zr, K, Sb, Nb, Mg, Ca, Mo, Zn, Cr, W, Bi, Sn, Ge, or Al, a doping element N is selected from at least one of Si, P, B, S, or Se, a doping element Q is selected from at least one of F, Cl, or N, 0.66≤x≤1, 0<a≤0.70, 0<b≤0.70, 0<c≤0.23, 0≤d<0.30, 0≤e≤0.30, 0≤f≤0.30, 0≤δ≤0.30, a+b+c+d+e=1, 0<e+f≤0.30, 0<(e+f)/a≤0.30, 0.20≤d+e+f≤0.30, and (b+c)/a≤1.5.