Garnet Solid Electrolyte Production via Ketone Solvent Mixing
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Solution Overview
Problem
The existing methods for producing garnet-type oxide solid electrolytes face challenges in achieving desired lithium ion conductivity due to lithium volatilization during high-temperature or long-duration firing processes, leading to instability and reduced conductivity.
Innovation Solution
A method involving the formation of a mixture using raw material solutions and a ketone-based solvent, followed by a first heating treatment to form a calcined body and a second heating treatment for main firing, which suppresses lithium volatilization and enhances lithium ion conductivity, using specific compositional formulas (Li7−3xGax)(La3−yNdy)Zr2O12 or (Li7−3x+yGax)(La3−yCay)Zr2O12 with controlled x and y values, and solvent amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If main firing is performed at high temperature (1200°C) or for long duration (36 hours), then the garnet-type oxide is fully formed, but lithium is volatilized and lithium ion conductivity deteriorates
Solution Approach 1:
The patent changes the firing temperature parameter from conventional high temperature (1200°C) to a lower range (900-1100°C) and adjusts the firing duration parameter to achieve complete reaction within 10-30 hours. This parameter optimization prevents lithium volatilization while ensuring complete formation of the garnet-type oxide structure, thereby maintaining high lithium ion conductivity.
Solution Approach 2:
The patent performs preliminary calcination treatment before main firing to pre-form the oxide structure and remove organic components. This preliminary action reduces the burden on the main firing process, allowing it to be conducted at lower temperatures for shorter durations, thus preventing lithium loss while achieving complete oxide formation.
2Manufacturing precision
If conventional planetary ball mill grinding is used, then raw materials are mixed, but the mixing homogeneity is insufficient leading to poor reaction completeness
Solution Approach 1:
The patent replaces the conventional mechanical planetary ball mill grinding system with a chemical solution-based mixing system. Raw materials are dissolved in appropriate solvents to form homogeneous solutions, which are then dried to produce uniformly mixed precursor powders. This chemical substitution approach achieves superior mixing homogeneity and reaction completeness compared to mechanical grinding.
Solution Approach 2:
The patent uses composite solvent systems (combining different solvents) to dissolve multiple raw materials with different solubility characteristics. This composite approach ensures complete dissolution and uniform distribution of all metal elements, leading to homogeneous precursor mixtures that react completely during firing.
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 approach results in a garnet-type solid electrolyte with improved bulk and grain boundary lithium ion conductivities, maintaining high conductivity even at lower temperatures and shorter firing times, reducing impurities and lithium loss, and enabling the production of thermally stable secondary batteries with excellent charge-discharge characteristics.
Implementation Method 1
forming a mixture by mixing raw material solutions containing elements shown in the compositional formula (1) or (2) with a ketone-based solvent
Implementation Method 2
forming a calcined body by subjecting the mixture to a first heating treatment
Implementation Method 3
performing main firing by subjecting the calcined body to a second heating treatment
Data Source
AI summary
A method for producing a solid electrolyte according to the present disclosure includes forming a mixture by mixing raw material solutions containing elements shown in the following compositional formula (1) or (2) with a ketone-based solvent, forming a calcined body by subjecting the mixture to a first heating treatment, and performing main firing by subjecting the calcined body to a second heating treatment.(Li7−3xGax)(La3−yNdy)Zr2O12 (1)(Li7−3x+yGax)(La3−yCay)Zr2O12 (2)Provided that 0.1≤x≤1.0 and 0<y≤0.2.