Sodium Ion Solid-State Conductors with Oxoferrate Structure
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Solution Overview
Problem
Current sodium ion batteries face challenges with limited availability and environmental concerns of existing solid-state conductors, as well as reactivity issues with metallic sodium in NASICON materials, necessitating the development of new materials with high ionic conductivity and stability.
Innovation Solution
The development of solid-state ion conductors represented by the formula NaFe_{¾}X_{¼}, where X is selected from Fe(IV), Si, Sn, Ti, Zr, V, or S, which are synthesized by melting (1−x)(NaFeO2)+x(XO2) to create thermodynamically stable materials with low ion diffusion barriers and low electronic conductivity, preserving the crystallographic structure and enhancing sodium ion mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If NASICON materials are used as solid-state sodium ion conductors, then high ionic conductivity is achieved, but reactivity with metallic sodium occurs
Solution Approach 1:
The patent modifies the chemical composition parameters of NASICON materials by substituting Zr and Si with Fe, and by doping with additional elements (Al, Ga, In, B, C, N, P, S, Se, Te). This compositional parameter change reduces chemical reactivity with metallic sodium while maintaining the crystallographic structure and ionic conductivity necessary for battery operation.
Solution Approach 2:
The patent creates composite oxide materials with the general formula NaZr1-x-ySiyP1-3x-2zO4-doped with Fe and other elements. This composite approach combines multiple elements to achieve both high ionic conductivity and chemical stability, resolving the contradiction between reactivity and conductivity by distributing functional roles across different compositional components.
2Reliability
If liquid electrolytes are used in batteries, then high ionic conductivity is achieved, but flammability and safety issues arise
Solution Approach 1:
The patent replaces the liquid electrolyte system with a solid-state oxide conductor system. This substitution eliminates the flammable organic solvents characteristic of liquid electrolytes while providing a solid material that conducts sodium ions, thereby resolving the safety issue without sacrificing ionic conductivity functionality.
Solution Approach 2:
The solid-state oxide conductor materials described in the patent create an inert environment within the battery structure. These materials do not support combustion and are chemically stable, effectively replacing the flammable liquid electrolyte environment with a non-flammable solid state environment that maintains ionic conductivity.
3Reliability
If existing solid-state conductor materials are used, then ionic conductivity is achieved, but material availability is limited and production cost increases
Solution Approach 1:
The patent employs common, abundant elements such as Fe, Al, Ga, In, B, C, N, P, S, Se, and Te in the solid-state conductor materials. These elements are more readily available and less expensive than the rare earth elements or specialized materials typically used in high-performance solid-state conductors, thereby improving ease of manufacture and material availability while maintaining ionic conductivity.
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
These new materials provide a stable, cost-effective, and environmentally friendly alternative to liquid-filled batteries, enhancing performance and safety by reducing inert materials and eliminating flammable organic liquids, while maintaining mechanical properties for various applications.
Implementation Method 1
Solid-state conductors that possess high ionic conductivity are needed for a broad range of electronic and power applications
Implementation Method 2
electrolytes in a battery conduct ions, block electrons, and separate the electrodes to prevent shorting
Implementation Method 3
synthesized by melting (1−x)(NaFeO2)+x(XO2) to create thermodynamically stable materials
Implementation Method 4
preserving the crystallographic structure
Implementation Method 5
create thermodynamically stable materials with low ion diffusion barriers and low electronic conductivity, preserving the crystallographic structure and enhancing sodium ion mobility
Data Source
AI summary
A solid-state conductor with sodium oxoferrate structure is disclosed. The conductor may be used in battery applications where it is preferable to avoid the use of a liquid electrolyte. The conductor may be produced from an initial NaFeO2 chemical composition. So as to add defects and allow for sodium ion mobility, Fe(IV), Si, Sn, Ti, Zr, V, P, or S can be added. For example, (1−x)(NaFeO2)+x(XO2) can be melted with the corresponding oxide XO2, where X is Fe(IV), Si, Sn, Ti, Zr, V, P, or S, and x is between 0.1 and 0.5. These dopants generally preserve the crystallographic structure while decreasing the ion mobility barrier.