Doped Garnet Solid-State Electrolyte With Lower Sintering Temperature
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Solution Overview
Problem
Garnet-type oxide solid-state electrolytes require high-temperature sintering for optimal lithium ion conductivity, but this process is limited by interface formation and side reactions, necessitating a method to improve sintering temperatures without compromising stability and conductivity.
Innovation Solution
A solid-state electrolyte composed of a compound represented by Formula (Li x M1 a )(La y M2 b )(Zr z M3 c )O 12, where M1, M2, and M3 are various cations, with specific ionic conductivity and crystalline phase composition, allowing for low-temperature formation and enhanced ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature sintering is used to achieve optimal lithium ion conductivity in garnet-type oxide solid-state electrolytes, then ionic conductivity is improved, but interface formation and side reactions occur compromising stability
Solution Approach 1:
The patent modifies the chemical composition parameters of the garnet-type oxide by incorporating specific dopants (e.g., Al, Ta, Nb at M3 sites; Li excess) to achieve high ionic conductivity at lower sintering temperatures, thereby avoiding the interface formation and side reactions that occur at high temperatures while maintaining reliable lithium ion conductivity
Solution Approach 2:
The patent creates a composite solid-state electrolyte system by combining garnet-type oxide with specific dopant elements in controlled ratios, forming a multi-component material that achieves both high ionic conductivity and chemical stability without requiring high-temperature sintering that would cause detrimental interface reactions
2Temperature
If sintering agents are introduced to lower sintering temperature, then sintering temperature is reduced, but the extent of improvement is limited and additional interface formation and side reaction issues may occur
Solution Approach 1:
The patent eliminates the need for external sintering agents by incorporating sintering-enhancing elements directly into the garnet lattice structure through dopant substitution, thereby achieving low-temperature sintering without introducing harmful interface formation and side reactions that accompany traditional sintering agent usage
Solution Approach 2:
The patent uses dopant elements (Al, Ta, Nb) as intermediaries that facilitate low-temperature sintering by modifying the lattice structure and creating favorable sintering conditions within the garnet lattice itself, avoiding the need for external sintering agents that would cause interface issues
3Temperature
If existing garnet elements and heterogeneous materials are used together to lower sintering temperature, then sintering temperature is reduced, but additional interface formation and side reaction issues may occur
Solution Approach 1:
The patent applies local quality modification by substituting specific elements at particular lattice sites (M1, M2, M3) with controlled compositions, creating localized regions with optimized properties that enable low-temperature sintering while maintaining overall material stability and avoiding harmful interface reactions
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 solution achieves high ionic conductivity and stability at lower temperatures, reducing the risk of interface issues and side reactions, while maintaining mechanical strength and uniformity in lithium battery applications.
Implementation Method 1
the ionic conductivity of the solid-state electrolyte is about 7 × 10 -6 S/cm or more at 25 °C
Implementation Method 2
in an extended X-ray absorption fine structure (EXAFS) spectrum of Zr in the garnet solid-state electrolyte, the ratio Ib/Ia of the intensity (Ia) of the first peak corresponding to an interatomic distance of 1.5 angstroms (Å)±0.5 Å and the intensity (Ib) of the second peak corresponding to an interatomic distance of 3.0 ű0.5 Å
Implementation Method 3
in an X-ray diffraction (XRD) spectrum of the solid-state electrolyte, a full width at half maximum of a peak at a diffraction angle of 16.8°2θ ±0.5°2θ is about 0.15°2θ or greater
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A solid-state electrolyte containing a compound represented by Formula 1 : Formula 1 (LixM1a)(LayM2b)(ZrzM3c)O12 wherein in Formula 1, M1 is a monovalent cation, a divalent cation, a trivalent cation, or a combination thereof, M2 is a monovalent cation, divalent cation, a trivalent cation, or a combination thereof, M3 is a monovalent cation, a divalent cation, a trivalent cation, a tetravalent cation, a pentavalent cation, a hexavalent cation, or a combination thereof, 6≤x≤8, 0≤a≤2, 2≤y≤3, 0≤b≤1, 0<z≤2, and 0≤c≤2, wherein in an extended X-ray absorption fine structure spectrum of Zr in the solid-state electrolyte, a ratio of an intensity of a first peak corresponding to an interatomic distance of 1.5±0.5 angstroms and an intensity of a second peak corresponding to an interatomic distance of 3.5±0.5 angstroms is about 0.3 to about 0.75, and an ionic conductivity of the solid-state electrolyte is about 7 × 10-6 to about 1×10-2 Siemens per centimeter.