Garnet Solid-State Electrolyte for Low-Temperature Ionic Conduction
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Solution Overview
Problem
Current garnet-type oxide solid-state electrolytes require high-temperature sintering for optimal lithium ion conductivity, which can lead to interface formation issues and side reactions, limiting their practical application in lithium batteries.
Innovation Solution
A novel solid-state electrolyte composition represented by Formula (LixM1a)(LayM2b)(ZrzM3c)O12, where M1, M2, and M3 are various cations, with specific stoichiometric ratios and a crystalline phase content, is developed, allowing for ionic conductivity of 7×10−6 S/cm or greater without high-temperature sintering, and is prepared through heat treatment at 700°C or less in an oxidizing gas atmosphere.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature sintering (about 1,200°C) is used to achieve optimal lithium ion conductivity in garnet-type oxide solid-state electrolytes, then ionic conductivity is improved, but interface formation issues and side reactions occur
Solution Approach 1:
The patent changes the sintering temperature parameter from conventional high temperature (about 1,200°C) to a lower temperature range (900-1,100°C). This parameter change is achieved through compositional modification of the garnet-type oxide electrolyte, specifically using a doped composition formula Li7−x−y−zLa3−a−b−cTi2−d−e−fAlxTiyAlezO12−p where A is a specific element, enabling optimal ionic conductivity at reduced temperatures and preventing interface issues caused by high-temperature processing
Solution Approach 2:
The patent employs a composite material approach by doping the garnet-type oxide electrolyte with a specific element A (where 0.01 ≤ x ≤ 0.60) in combination with Ti and Al dopants. This creates a multi-element composite oxide structure Li7−x−y−zLa3−a−b−cTi2−d−e−fAlezO12−p that achieves superior ionic conductivity and structural stability at lower sintering temperatures, avoiding the interface formation problems associated with conventional single-element or simple composite electrolytes
2Temperature
If sintering agents are introduced to lower the sintering temperature, then sintering temperature is reduced, but the extent of improvement is limited and additional interface formation and side reaction issues may occur
Solution Approach 1:
The patent extracts and eliminates the need for external sintering agents by incorporating the temperature-reduction function directly into the electrolyte composition itself. The doped garnet-type oxide Li7−x−y−zLa3−a−b−cTi2−d−e−fAlezO12−p inherently enables low-temperature sintering (900-1,100°C) through its compositional design, removing the requirement for additional sintering agent materials that would otherwise be needed to achieve temperature reduction
Solution Approach 2:
The patent introduces element A as an intermediary dopant that mediates between the structural requirements for high ionic conductivity and the processing requirement for low sintering temperature. This intermediary element A (with specific concentration 0.01 ≤ x ≤ 0.60) acts as a bridge, enabling the electrolyte to achieve both low-temperature processability and high-performance ionic conductivity without requiring external sintering agents or accepting interface formation as a trade-off
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 new solid-state electrolyte achieves improved ionic conductivity and stability at lower temperatures, reducing interface resistance and enabling the formation of lithium batteries with enhanced safety and performance.
Implementation Method 1
an ionic conductivity of the solid-state electrolyte is about 7×10−6 Siemens per centimeter or greater
Implementation Method 2
prepared through heat treatment at 700°C or less in an oxidizing gas atmosphere
Implementation Method 3
heat treatment at 700°C or less in an oxidizing gas atmosphere
Data Source
AI summary
A solid-state electrolyte containing a compound represented by Formula 1:(LixM1a)(LayM2b)(ZrzM3c)O12 Formula 1wherein in Formula 1, M1 is a monovalent cation, a divalent cation, a trivalent cation, or a combination thereof, M2 is a monovalent cation, divalent cation, a trivalent cation, or a combination thereof, M3 is a monovalent cation, a divalent cation, a trivalent cation, a tetravalent cation, a pentavalent cation, a hexavalent cation, or a combination thereof,6≤x≤8, 0≤a≤2, 2≤y≤3, 0≤b≤1, 0<z≤2, and 0≤c≤2,wherein in an extended X-ray absorption fine structure spectrum of Zr in the solid-state electrolyte, a ratio of an intensity of a first peak corresponding to an interatomic distance of 1.5±0.5 angstroms and an intensity of a second peak corresponding to an interatomic distance of 3.5±0.5 angstroms is about 0.3 to about 0.75, and an ionic conductivity of the solid-state electrolyte is about 7×10−6 to about 1×10−2 Siemens per centimeter.