NASICON Electrolyte Aliovalent Doping for Room Temperature Conductivity
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Solution Overview
Problem
Conventional lithium-ion batteries face limitations due to lithium supply constraints, high costs, short cycle-life, and safety concerns, while solid-state sodium-ion batteries require high conductivity at room temperature to be competitive, which is not adequately met by conventional NASICON electrolytes.
Innovation Solution
Doping the zirconium site in NASICON electrolytes with +2 oxidation state cations such as Co2+, Ni2+, and Zn2+ to enhance ionic conductivity, achieved through a process involving ball milling, calcining, and sintering of sodium, silicon, phosphate, and zirconium sources with dopants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional NASICON electrolytes are used in solid-state sodium-ion batteries, then structural stability is maintained, but ionic conductivity at room temperature is insufficient
Solution Approach 1:
The patent applies parameter changes by substituting Zr4+ ions with aliovalent cations (M3+ or M2+) at the zirconium site, which alters the electrostatic interactions between sodium ions and the lattice. This substitution changes the activation energy for ion transport and increases sodium ion conductivity at room temperature while maintaining structural stability through controlled doping levels (x ≤ 2.0)
Solution Approach 2:
The patent creates composite materials by doping NASICON with aliovalent cations (Co3+, Ni3+, Zn3+, Co2+, Ni2+, Zn2+), forming a composite electrolyte system Na3+2xMxZr2−xSi2PO12 that combines the structural stability of NASICON with enhanced ionic conductivity from the dopant elements
2Use of energy by moving object
If lithium-ion batteries are used, then high energy density is achieved, but cost and supply constraints increase
Solution Approach 1:
The patent replaces expensive lithium with abundant, inexpensive sodium as the charge carrier, using readily available sodium compounds (Na2CO3, NaOH, NaCl) as starting materials. This substitution dramatically reduces material costs while maintaining comparable energy density through optimized NASICON electrolyte composition
3Reliability
If conventional NASICON is doped to increase conductivity, then ionic mobility improves, but structural stability may deteriorate
Solution Approach 1:
The patent optimizes the dopant concentration parameter (x) to be ≤ 2.0, which is sufficient to increase sodium content and conductivity while preventing excessive lattice distortion. This controlled parameter change maintains the NASICON framework stability while achieving enhanced ionic conductivity
Solution Approach 2:
The patent introduces local quality changes by substituting specific Zr4+ sites with aliovalent cations, creating localized regions of modified electrostatic potential that facilitate sodium ion transport without compromising the overall structural integrity of the NASICON framework
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 approach significantly increases sodium ion conductivity at room temperature, improving the performance and competitiveness of solid-state sodium-ion batteries by enhancing charge carrier mobility and structural stability.
Implementation Method 1
doping the zirconium site in NASICON electrolytes with +2 oxidation state cations such as Co2+, Ni2+, and Zn2+ to enhance ionic conductivity
Data Source
AI summary
The present invention is directed to solid NASICON electrolytes in which the zirconium site is doped with a 2+ oxidation state cation. The present invention is also directed to methods of making the solid electrolytes and methods of using the solid electrolytes in batteries and other electrochemical technologies.