Garnet Ceramic Solid Electrolyte for Lithium Batteries
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Solution Overview
Problem
The development of a solid-state electrolyte material for all-solid-state lithium secondary batteries that offers both lithium resistance and high Li ion conductivity has been hindered by the limitations of existing garnet-type lithium ion-conducting oxides, particularly Li7La3Zr2O12 (LLZ), which fail to demonstrate practical usability due to issues with sinterability and conductivity.
Innovation Solution
A ceramic material with a garnet-type or garnet-like crystal structure, composed of Li, La, Zr, Nb, Ta, and Al, with specific molar ratios that enhance sinterability and Li ion conductivity, is developed by substituting Zr with Nb and/or Ta, and incorporating Al to improve sintered body density and conductivity, allowing for the production of a stable and efficient solid-state electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Li7La3Zr2O12 (LLZ) garnet-type oxide is used as solid-state electrolyte, then lithium resistance is improved, but Li ion conductivity and sinterability are insufficient for practical use
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition of the LLZ garnet-type oxide through substitution of Zr4+ ions with Nb5+ and Ta5+ ions at controlled ratios. This compositional parameter change enables simultaneous improvement of Li ion conductivity and sinterability while maintaining lithium resistance, resolving the technical contradiction between reliability and ease of manufacture
Solution Approach 2:
The patent creates a composite material system by combining multiple elements (Li, La, Zr, Nb, Ta, Al) in specific proportions within the garnet structure. The composite nature of this material allows synergistic effects where Nb/Ta substitution enhances ionic conductivity and Al addition improves sinterability, while the overall structure maintains lithium resistance
2Power
If Li metals are used for negative electrode, then battery performance and energy density are improved, but dendrite precipitation and safety issues occur
Solution Approach 1:
The patent introduces a solid-state electrolyte membrane as an intermediary layer between the Li metal negative electrode and the rest of the battery system. This membrane acts as a physical barrier that prevents dendrite precipitation and penetration while allowing Li ion transport, thereby enabling the use of high-performance Li metal electrodes without the associated safety hazards
3Reliability
If solid-state electrolyte is used instead of liquid electrolyte, then safety and leakage prevention are improved, but Li ion conductivity is insufficient
Solution Approach 1:
The patent changes the physical and chemical parameters of the solid-state electrolyte by substituting cations in the garnet structure and controlling stoichiometry. These parameter changes reduce the activation energy for Li ion transport and increase ionic conductivity to levels comparable with or exceeding liquid electrolytes, while maintaining the inherent safety advantages of solid-state systems
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 resulting ceramic material achieves satisfactory Li ion conductivity and sinterability, enabling its use as a solid-state electrolyte in lithium secondary batteries, enhancing battery performance and safety by preventing lithium metal dendrite formation and improving energy density.
Implementation Method 1
garnet-type lithium ion-conducting oxide
Implementation Method 2
a LLZ sintered body having satisfactory sinterability
Data Source
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AI summary
The present invention provides a ceramic material capable of demonstrating compactness and Li ion conductivity to an extent that enables the use of the ceramic material as a solid-state electrolyte material for a lithium secondary battery, or the like. A ceramic material containing Li, La, Zr, Nb and/or Ta, as well as O and having a garnet-type or garnet-like crystal structure is used.