Multiphase LLZO Garnet Electrolytes With Secondary Inclusions for Sintering
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Solution Overview
Problem
Current solid-state Li ion batteries face limitations due to instability and secondary phase formation in existing electrolyte materials, which hinder their commercialization, particularly with lithium-stuffed garnet-based electrolytes that require phase purity and specific doping levels to achieve high ionic conductivity.
Innovation Solution
A multiphase thin film solid-state electrolyte comprising a primary cubic phase lithium-stuffed garnet with secondary phase inclusions, where the primary phase constitutes 70-99.9% of the volume and secondary phases constitute 0.1-30% of the volume, exceeding the solubility limit of Al in LLZO, and processed by calcining at temperatures above 800°C to enhance stability and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium-stuffed garnet electrolyte is doped with Al and/or Al2O3 to achieve high ionic conductivity, then ionic conductivity is improved, but secondary crystalline phases precipitate when doping exceeds solubility limit
Solution Approach 1:
The patent changes the doping parameters by using multiple dopants (Al, Ta, Nb) in specific combinations and ratios, rather than single dopant systems. This allows achieving high ionic conductivity while maintaining phase stability through optimized compositional parameters that prevent secondary phase precipitation.
Solution Approach 2:
The patent creates a composite doping system combining Al with Ta and/or Nb in the lithium-stuffed garnet structure. This composite approach allows the dopants to work synergistically, where Ta and Nb help stabilize the cubic phase while Al provides ionic conductivity pathways, resolving the contradiction between conductivity enhancement and phase stability.
2Stability of the object's composition
If lithium-stuffed garnet electrolyte is made phase pure with minimal doping to maintain stability, then phase stability is improved, but ionic conductivity decreases
Solution Approach 1:
The patent optimizes dopant concentration parameters and compositional ratios to achieve a sweet spot where sufficient doping provides high ionic conductivity while remaining below the precipitation threshold for secondary phases. The specific parameter range of Al0.05Al0.05Ta0.05Nb0.05 doping achieves this balance.
Solution Approach 2:
By using a composite doping strategy with Al, Ta, and Nb together, the patent achieves enhanced ionic conductivity through Al while Ta and Nb contribute to phase stabilization, thereby maintaining phase purity at higher effective doping levels than would be possible with Al alone.
3Ease of manufacture
If existing garnet materials are used with known processing techniques, then manufacturing is simplified, but stability within operating voltage ranges and chemical compatibility with electrodes deteriorates
Solution Approach 1:
The patent modifies the compositional parameters of the garnet electrolyte by introducing a multi-dopant system (Al, Ta, Nb) with optimized ratios. This compositional change enhances electrochemical stability and chemical compatibility with electrodes while maintaining manufacturability through conventional solid-state processing techniques.
Solution Approach 2:
The patent applies composite material principles by combining multiple dopant elements in the garnet structure, creating a composition that exhibits improved electrochemical stability and interfacial compatibility compared to undoped or singly-doped garnets, while still using standard manufacturing processes.
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 results in improved electrochemical and mechanical properties, including increased stability between 0-4.5V, chemical compatibility with Li metal, and enhanced sinterability, leading to higher energy density and performance in solid-state batteries.
Implementation Method 1
processed by calcining at temperatures above 800°C to enhance stability and conductivity
Data Source
AI summary
The instant disclosure sets forth multiphase lithium-stuffed garnet electrolytes having secondary phase inclusions, wherein these secondary phase inclusions are material(s) which is/are not a cubic phase lithium-stuffed garnet, but which is/are entrapped or enclosed within a lithium-stuffed garnet. When the secondary phase inclusions described herein are included in a lithium-stuffed garnet at 30-0.1 volume %, the inclusions stabilize the multiphase matrix and allow for improved sintering of the lithium-stuffed garnet. The electrolytes described herein, which include lithium-stuffed garnet with secondary phase inclusions, have an improved sinterability and density compared to phase pure cubic lithium-stuffed garnet having the formula Li7La3Zr2O12.