Dry Doping Process for Doped LLZO Solid Electrolyte
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Solution Overview
Problem
Existing methods for preparing doped lithium lanthanum zirconium oxide (LLZO) face challenges in scalability and control over dopant content, particularly during co-precipitation, leading to variability in the resulting crystal structure and lithium conductivity.
Innovation Solution
A dry doping process where a powdered dopant is mixed with a pre-prepared co-precipitated lanthanum zirconium oxide (LZO) precursor and a lithium salt, followed by calcination in an oxygen-containing atmosphere, allowing for precise control over the Li:La:Zr:X ratio and enabling the incorporation of multiple dopant species.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If co-precipitation method is used to prepare doped LLZO, then scalability is improved, but control over dopant content deteriorates leading to variability in crystal structure and lithium conductivity
Solution Approach 1:
The preparation process is divided into two independent stages: first preparing the LZO precursor through co-precipitation (achieving scalability), then separately adding the dopant through dry mixing before calcination (achieving precise dopant control). This segmentation allows each stage to be optimized independently for its specific goal.
Solution Approach 2:
The LZO precursor is prepared in advance through co-precipitation with controlled La:Zr ratio, and then stored as a stable intermediate product. The dopant is added in a separate preliminary mixing step before final calcination, allowing precise control of dopant content without interfering with the co-precipitation process.
2Reliability
If multiple dopant species are incorporated to enhance lithium conductivity, then performance is improved, but process complexity increases
Solution Approach 1:
Multiple dopant species are combined in a single dry mixing step with the LZO precursor and lithium salt, followed by one calcination process. This merging approach allows incorporation of multiple dopants without requiring separate processing steps for each, thus enhancing lithium conductivity while maintaining process simplicity.
3Ease of manufacture
If traditional co-precipitation is used for doped LLZO, then a limited pool of dopant materials can be used, but this restricts versatility
Solution Approach 1:
The dopant addition step is extracted from the co-precipitation process itself and performed as a separate dry mixing operation. This extraction removes the constraint that limited dopant choices, allowing any dopant material that can be ground and mixed in powder form to be incorporated while maintaining the simplicity of the co-precipitation process for the LZO precursor.
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
This method provides a robust and versatile process for producing doped-LLZO with uniform distribution of elements, enhancing lithium conductivity and stability, and allowing for a wide range of dopant species, thus overcoming the limitations of traditional co-precipitation methods.
Implementation Method 1
co-precipitation of lanthanum hydroxide (La(OH)3), zirconium oxide (ZrO2) and/or zirconium hydroxide (Zr(OH)4), and a dopant oxide or hydroxide (if applicable) from an aqueous solution
Implementation Method 2
calcined (also referred to as sintering) at high temperature (e.g., 450 to 1200° C.) to form the LLZO material
Data Source
AI summary
A process for preparing doped-lithium lanthanum zirconium oxide (doped-LLZO) is described herein. The method involves dry doping of a co-precipitated lanthanum zirconium oxide (LZO) precursor. Dry doping is a process in which a dry powdered dopant is ground and mixed with a pre-prepared co-precipitated LZO precursor and a lithium salt to provide a LLZO precursor composition, which is subsequently calcined to form a doped-LLZO. The process described herein comprises calcining a dry, powdered (e.g., micron, sub-micron or nano-powdered) mixture of a co-precipitated LZO precursor, a dopant salt or oxide, and a lithium salt under an oxygen-containing atmosphere at a temperature in the range of about 500 to about 1100° C., and recovering the doped-LLZO after calcining.