Zinc-Containing Sodium-Ion Cathode for Low-Alkali Slurry Stability
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Solution Overview
Problem
Existing cathode materials for sodium ion batteries, particularly layered oxides, suffer from high cost due to the use of rare and precious metals like cobalt and nickel, and surface alkali residues that degrade performance and stability, leading to lower capacity and cycle life.
Innovation Solution
A zinc-containing cathode material with a specific chemical formula and structure, replacing some rare metals with zinc, stabilizes the crystal structure, reduces surface alkali content, and provides vacancies for sodium ion intercalation, enhancing rate performance and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If rare and precious metals like cobalt and nickel are used in cathode materials, then the battery capacity and voltage are improved, but the manufacturing cost increases significantly
Solution Approach 1:
The patent replaces expensive rare metals (cobalt, nickel) with cheaper common metals (zinc, manganese, iron) in the cathode material composition. This substitution directly addresses the cost issue while maintaining acceptable performance through optimized formulation of the cheaper metal combination.
Solution Approach 2:
The patent modifies the chemical composition parameters of the cathode material by adjusting the ratios of zinc, manganese, iron, and sodium oxides. By changing these compositional parameters, the material achieves optimal performance with reduced reliance on expensive rare metals, thereby lowering manufacturing cost while maintaining capacity.
2Ease of manufacture
If excessive sodium salt is added during preparation to compensate for sodium loss, then the sintering process is simplified, but residual alkali remains on the surface causing deterioration and gelation
Solution Approach 1:
The patent optimizes the sodium salt addition parameter within a specific range (0.5-2 times stoichiometric amount) and controls sintering temperature (900-1100°C) and time (10-50 hours) to achieve complete sodium incorporation while minimizing residual alkali. This parameter optimization resolves the contradiction between preparation simplicity and material stability.
Solution Approach 2:
The patent performs preliminary mixing of all raw materials (zinc oxide, manganese oxide, iron oxide, sodium carbonate/sodium hydroxide) before sintering to ensure uniform distribution. This preliminary action prevents localized sodium excess that would lead to residual alkali, while maintaining a simple one-step sintering process.
3Quantity of substance
If layered oxide structure is used to achieve high specific capacity, then the energy density is improved, but the surface is prone to absorb water and react with air causing deterioration
Solution Approach 1:
The patent creates a composite cathode material system combining zinc oxide, manganese oxide, iron oxide, and sodium compounds in specific ratios. This composite formulation produces a layered oxide structure with enhanced stability compared to conventional single-component layered oxides, reducing susceptibility to water absorption and air reaction while maintaining high specific capacity.
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 zinc-containing cathode material achieves high discharge capacity and improved air stability, reducing material collapse and increasing the usable capacity and rate performance of sodium ion batteries.
Implementation Method 1
replacing some rare and precious metals with zinc element can stabilize the crystal structure of the material
Implementation Method 2
frequent de-intercalation of sodium ions and the presence of zinc oxide play a supporting role
Implementation Method 3
the presence of zinc oxide play a supporting role, which can effectively reduce the collapse of the material structure
Data Source
AI summary
The present invention discloses a cathode material for a sodium ion battery and a preparation method and application thereof. The general chemical formula of the cathode material is Na1+aMyZnxO2+c, where −0.40≤a≤0.25, 0.1<x≤0.22, 0.78<y≤0.93, −0.3<c<0.3. M is one or a combination of two or more selected from the group consisting of Mn, Fe, Ni, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Ti, Mg, Ta, Nb, V, Sc, Sr, B and Cu. In the powder X-ray diffraction graph, there are at least five diffraction peaks exist when 2θ is 30°-40°. A minor strong peak exist when 2θ is around 16° and a major strong peak exists when 2θ is around 41°. The sodium ion cathode material of the present invention has a low residual alkali content and avoids the occurrence of gelation phenomenon in the battery slurrying process. In addition, the capacity and rate of the sodium ion battery prepared therefrom are at a relatively high level.