Dual-Doped Sodium Cathode Material for Conductivity and Rate Performance
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Solution Overview
Problem
Sodium-ion batteries suffer from low energy density and rate performance due to poor conductivity and impurities in the Fe-based polyanionic phosphate positive electrode material, which affects capacity and polarization.
Innovation Solution
A positive electrode active material comprising Na4-xKyFe3-pMq(PO4)2P2O7, where M includes elements like Ni, Co, Mn, V, Ti, Mo, Nb, W, Cr, Zn, Zr, Ca, Mg, Cu, Sr, Y, or Al, with dual-site doping of K and metal M at the Na-site and Fe-site, and optionally incorporating carbon, to enhance ionic and electronic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dual-site doping with K and metal M is performed, then ionic conductivity and electronic conductivity are improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by systematically varying the doping amounts of K (0.01≤x≤0.2) and metal M (0.01≤p≤0.2, 0.01≤q≤0.15) to optimize conductivity. The specific compositional parameters are tuned to achieve maximum ionic and electronic conductivity while maintaining phase purity, resolving the contradiction between performance improvement and manufacturing complexity through precise parameter control.
Solution Approach 2:
The patent creates a composite doped material Na4-xKyFe3-pMq(PO4)2P2O7 by combining multiple elements (Na, K, Fe, M where M can be Ni, Co, Mn, V, Ti, Mo, Nb, W, Cr, Zn, Zr, Ca, Mg, Cu, Sr, Y, or Al) in specific ratios. This composite approach improves both ionic and electronic conductivity simultaneously, addressing the reliability enhancement while the defined compositional ranges keep the manufacturing process manageable.
2Reliability
If dual-site doping with K and metal M is performed, then electronic conductivity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise parameter ranges for doping: 0.01≤x≤0.2 for K content, 0.01≤p≤0.2 for Fe-site doping, and 0.01≤q≤0.15 for metal M content. These defined parameters provide clear manufacturing targets that balance the need for high electronic conductivity with achievable precision in production, resolving the contradiction between performance and manufacturing precision requirements.
Solution Approach 2:
The patent implements local quality by specifically targeting the Fe-site for metal M doping while maintaining overall compositional control. The metal M is incorporated at the Fe-site with controlled amounts (0.01≤p≤0.2, 0.01≤q≤0.15), creating localized improvements in electronic conductivity without requiring extreme precision across the entire material system, thus resolving the contradiction between electronic conductivity enhancement and manufacturing precision.
3Reliability
If carbon is added to the positive electrode active material, then conductivity is improved, but energy density may be reduced
Solution Approach 1:
The patent optimizes the carbon content parameter within specific ranges (0.5%-6% by mass) to achieve the desired balance. This parameter control ensures sufficient carbon is present to improve conductivity through the carbon coating and internal carbon mixture, while limiting the amount to minimize the dilution effect on energy density, thus resolving the contradiction between conductivity enhancement and energy density maintenance.
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 dual-site doping and carbon addition improve the ionic and electronic conductivity, increasing energy density and rate performance of sodium-ion batteries by reducing impurities and enhancing sodium-ion deintercalation.
Implementation Method 1
a Na-site and a Fe-site of the positive electrode active material are doped with element K and metal element M respectively, i.e., dual-site doping is performed in the positive electrode active material, so that the ionic conductivity and electronic conductivity of the positive electrode active material can be increased
Implementation Method 2
optionally incorporating carbon, to enhance ionic and electronic conductivity
Implementation Method 3
Sodium batteries utilize the deintercalation of sodium ions between positive and negative electrodes to achieve charging and discharging
Data Source
AI summary
A positive electrode active material and a method for preparing the same, a positive electrode plate, a battery and an electrical apparatus. The positive electrode active material includes Na4-xKyFe3-pMq(PO4)2P2O7, where M includes at least one of Ni, Co, Mn, V, Ti, Mo, Nb, W, Cr, Zn, Zr, Ca, Mg, Cu, Sr, Y or Al, with 0<x≤0.4, 0<y≤0.4, 0<p≤0.3, and 0<q≤0.3.