Two-Stage Sintering for Solid-State Electrolyte Powder
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Solution Overview
Problem
Solid-state electrolytes in lithium batteries face limitations due to low ionic conductivity, which is hindered by grain boundaries and the migration rate of lithium ions, failing to meet practical requirements for energy density and safety.
Innovation Solution
A two-stage sintering process is employed, first in an oxygen-free environment at a lower temperature to form a solid-state electrolyte powder precursor, followed by an oxygen-containing sintering process at a higher temperature, along with pre- and post-grinding steps to achieve uniform particle size and enhance phase conversion, improving the quality and yield of the solid-state electrolyte powder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a one-step sintering process is used, then the process is simple and fast, but the ionic conductivity is low and the phase conversion is incomplete
Solution Approach 1:
The sintering process is divided into two distinct stages: an oxygen-free sintering stage at 800-1100°C to form the precursor mixture, followed by an oxygen-containing sintering stage at 850-1280°C to achieve complete phase conversion to cubic LLZO. This segmentation allows each stage to optimize for its specific function, resolving the contradiction between process simplicity and product quality.
Solution Approach 2:
The oxygen-free sintering stage performs preliminary action by forming the solid-state electrolyte powder precursor mixture with appropriate phase structure before the final oxygen-containing sintering stage. This preliminary phase formation prepares the material for complete cubic phase conversion in the second stage, improving overall ionic conductivity.
2Manufacturing precision
If the sintering temperature is increased to improve phase conversion, then the cubic LLZO formation is enhanced, but the energy consumption increases and grain boundary issues persist
Solution Approach 1:
The invention changes the oxygen concentration parameter between the two sintering stages (oxygen-free first, then oxygen-containing) and adjusts temperature parameters sequentially (800-1100°C then 850-1280°C). This parameter optimization achieves complete cubic phase conversion while managing energy consumption efficiently.
Solution Approach 2:
The two-stage sintering process creates local quality differences in the sintering atmosphere (oxygen-free vs. oxygen-containing) and temperature zones, allowing different regions of the sintering process to serve different functions: precursor formation and final phase conversion.
3Stability of the object's composition
If grinding is performed before sintering to reduce particle size, then the mixing uniformity is improved, but the process time increases
Solution Approach 1:
Grinding is performed as a preliminary action before the oxygen-free sintering stage to ensure uniform mixing of the salt mixture. This preliminary size reduction and mixing uniformity preparation enables the subsequent sintering stages to proceed efficiently with complete phase conversion.
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 stable and cost-effective process, enhancing the ionic conductivity of the solid-state electrolyte powder, improving its quality and yield, and enabling the production of high-purity cubic LLZO, thus addressing the limitations of conventional one-step sintering processes.
Implementation Method 1
An oxygen-free sintering process is performed at a first sintering temperature, such that a salt mixture forms a solid-state electrolyte powder precursor mixture
Implementation Method 2
An oxygen-containing sintering process is performed at a second sintering temperature, such that the solid-state electrolyte powder precursor mixture forms the solid-state electrolyte powder
Implementation Method 3
the oxygen-containing sintering process is performed such that the refined solid-state electrolyte powder precursor mixture forms the solid-state electrolyte powder
Implementation Method 4
performing a grinding process before the oxygen-free sintering process, such that the salt mixture forms a refined salt mixture
Data Source
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AI summary
A method for preparing a solid-state electrolyte powder includes the following steps. An oxygen-free sintering process is performed at a first sintering temperature, such that a refined salt mixture forms a solid-state electrolyte powder precursor mixture. An oxygen-containing sintering process is performed at a second sintering temperature, such that the solid-state electrolyte powder precursor mixture forms a solid-state electrolyte powder, in which the second sintering temperature is higher than the first sintering temperature.