Monoclinic Complex Oxide Electrolyte for Dense Li-Ion Conduction
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Solution Overview
Problem
Current solid electrolytes for all-solid-state lithium ion secondary batteries face challenges in achieving high density and high lithium ion conductivity, particularly at low temperatures, due to grain boundary resistance and interface resistance, and existing methods struggle to produce high-density compacts with low activation energy.
Innovation Solution
A complex oxide with a monoclinic crystal structure, represented by Li4−xSr2−xLaxZrO6, is produced using a rapid cooling method with infrared condensed heating, resulting in a high-density single crystal with low activation energy and high ion conductivity, which can be easily cut to thin pieces for use as a solid electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cubic garnet-type structure materials are used as solid electrolytes, then high lithium ion conductivity at room temperature is achieved, but high-density compact production is difficult and grain boundary resistance is high
Solution Approach 1:
The invention changes the crystal structure parameter from cubic garnet-type to monoclinic structure, and modifies the chemical composition parameters by incorporating Sr and La elements in specific ratios (Li4-xSryLazZrO6 where y=1.2 and z=1.2), achieving both high density and high lithium ion conductivity with low activation energy
Solution Approach 2:
The invention creates a composite oxide material by combining multiple elements (Li, Sr, La, Zr, O) in a specific monoclinic structure, where the composite nature of the material enables simultaneous achievement of high density, high ion conductivity, and low activation energy that cannot be achieved with single-element or simpler composite structures
2Reliability
If cubic garnet-type solid electrolytes are used, then high ion conductivity is achieved at room temperature, but activation energy is high (near 0.45 eV) and conductivity decreases at low temperatures
Solution Approach 1:
The invention changes the crystal structure from cubic to monoclinic and adjusts the chemical composition parameters (specifically y=1.2 and z=1.2 in Li4-xSryLazZrO6), which results in significantly reduced activation energy (0.20-0.30 eV) while maintaining high ion conductivity across a wide temperature range including low temperatures
3Reliability
If single crystal materials are produced to reduce grain boundary resistance, then high lithium ion conductivity is achieved, but production difficulty and cost increase
Solution Approach 1:
The invention changes the crystal structure parameter to monoclinic system with specific space group P21/n, which enables the material to form high-density compacts more easily through conventional sintering methods, reducing production difficulty while maintaining the benefits of single crystal-like performance
4Ease of manufacture
If conventional sintering methods are used for cubic garnet-type materials, then production is possible, but high-density compact formation is difficult
Solution Approach 1:
The invention changes the crystal structure from cubic to monoclinic and optimizes the chemical composition (Li4-xSryLazZrO6 with y=1.2, z=1.2), which fundamentally improves the sinterability of the material, enabling high-density compact formation (99% or more relative density) through conventional sintering methods that are already industrially established
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 complex oxide achieves high lithium ion conductivity (e.g., 6.0×10−4 S/cm) and low activation energy (0.20-0.30 eV), enabling the development of high-density, thin-film solid electrolytes for all-solid-state lithium ion secondary batteries with improved performance and size reduction potential.
Implementation Method 1
melted and rapidly cooled by an FZ method using infrared condensed heating
Implementation Method 2
melted and rapidly cooled by an FZ method using infrared condensed heating
Implementation Method 3
complex oxide having a crystal structure with high density and high ion conductivity
Data Source
AI summary
Provided is a complex oxide having high density and high lithium ion conductivity and low activation energy. The complex oxide has a chemical composition represented by Li4−xSr2−xLaxZrO6 (0≤x≤1.0) and belongs to a monoclinic space group P21/n. The relative density of this complex oxide can be made to be 100%. The lithium ion conductivity of this complex oxide can be made to be 6.0×10−4 S/cm or more. This complex oxide is produced by melting at least a part of a raw material having a chemical composition represented by Li(4−x)ySr(2−x)zLaxZrO6 (0≤x≤1.0, 1<y and 1<z) to form a molten portion and moving the molten portion at a movement speed of 8 mm/h or faster.