Lithium-Ion Glass Ceramic with Garnet Phase
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Solution Overview
Problem
Current solid electrolytes for lithium-ion batteries face challenges in achieving high ionic conductivity while maintaining electronic conductivity below certain magnitudes, stability against metallic lithium, and cost-effectiveness, particularly due to complex production processes and material instability under air exposure.
Innovation Solution
A lithium-ion conducting glass ceramic with a garnet-like main crystal phase and an amorphous proportion of at least 5 wt.-%, produced using a melting route and subsequent temperature treatment, which enhances conductivity and stability, and can be produced in a cost-effective manner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sulfidic compositions are prepared by grinding and temperature treatment under protective gas, then ionic conductivities of more than 10−3 S/cm are achieved, but the production process becomes complicated and costly due to air instability and water sensitivity
Solution Approach 1:
The patent applies inert atmosphere by performing all production and processing steps under protective gas (nitrogen or argon) to prevent oxidation and hydrolysis of the sulfidic glass ceramic. The melting, casting, crystallization, and machining operations are conducted in inert environments, eliminating the need for complex moisture-proof handling procedures and enabling stable production of high-conductivity materials.
2Reliability
If oxidic systems with NaSiCon are used to achieve conductivities of more than 10−4 S/cm, then ionic conductivity is improved, but additional protective layers are required against metallic lithium and costly raw materials like germanium, tantalum or gallium are needed
Solution Approach 1:
The patent employs composite materials by combining sulfidic glass phases with crystalline phases (such as Li2SiO3, Li2Si2O5, or garnet-like phases) to achieve high ionic conductivity. This composite approach allows the material to attain >10−3 S/cm conductivity without requiring expensive dopants like germanium or tantalum, and without needing additional protective layers against metallic lithium.
3Reliability
If garnet-like crystal phases are used to achieve conductivities in the order of 10−4 S/cm, then ionic conductivity is improved, but high temperatures up to about 1250° C. are necessary leading to strong lithium evaporation and phase transition issues
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition to include specific sulfide content (10-40 wt%) and oxide ratios that enable crystallization at lower temperatures (900-1100°C). This compositional adjustment prevents the tetragonal-to-cubic phase transition and reduces lithium evaporation while maintaining ionic conductivity in the range of 10−4 to 10−3 S/cm.
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 glass ceramic achieves ion conductivities of at least 5·10−5 S/cm, with the amorphous phase contributing to improved conductivity and stability, allowing for longer battery service life and increased capacity.
Implementation Method 1
lithium-ion conducting glass ceramic with garnet-like main crystal phase... achieves ion conductivities of at least 5·10−5 S/cm
Implementation Method 2
an amorphous proportion of at least 5 wt.-%... the amorphous phase contributing to improved conductivity
Data Source
AI summary
A glass ceramic containing lithium-ions and having a garnet-like main crystal phase having an amorphous proportion of at least 5% is disclosed. The garnet-like main crystal phase preferably has the chemical formula Li7+x−yMxIIM3−xIIIM2−yIVMyVO12, wherein MII is a bivalent cation, MIII is a trivalent cation, MIV is a tetravalent cation, MV is a pentavalent cation. The glass ceramic is prepared by a melting technology preferably within a Skull crucible and has an ion conductivity of at least 5·10−5 S/cm, preferably of at least 1·10−4 S/cm.