Dual-Doped Lanthanum Fluoride Electrolyte for Room-Temperature Ion Conduction
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Solution Overview
Problem
Conventional fluoride ion conductive materials, such as lanthanum fluoride doped with alkaline earth metals, exhibit high fluoride ion conductivity only at elevated temperatures, which is insufficient for practical battery operation at room temperature.
Innovation Solution
A novel fluoride ion conductive material represented by La1-x-yM1xM2yF3-x-2y, where M1 is an alkaline earth metal and M2 is an alkali metal, is developed, enhancing fluoride ion conductivity at room temperature by increasing fluorine vacancies in the lanthanum fluoride crystal, with specific compositional ranges for x and y to optimize conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fluoride ion conductive materials (lanthanum fluoride doped with alkaline earth metals) are used, then fluoride ion conductivity is improved at elevated temperatures, but fluoride ion conductivity deteriorates at room temperature
Solution Approach 1:
The patent changes the compositional parameters by introducing a third element (alkali metal or transition metal) in addition to the traditional alkaline earth metal dopant. This creates a new compositional space La1-x-yM1xM2yF3-x-2y that enables room temperature operation. The dual-doping strategy with controlled stoichiometry ratios optimizes the balance between structural stability and ionic conductivity across different temperatures.
Solution Approach 2:
The patent creates a composite doped structure by combining multiple dopant elements (alkaline earth metal M1 and alkali/transition metal M2) within the lanthanum fluoride matrix. This multi-component doping approach synergistically enhances fluoride ion conductivity at room temperature while maintaining structural integrity, resolving the contradiction between temperature adaptability and conductivity reliability.
2Reliability
If fluoride ion conductivity is enhanced by increasing fluorine vacancies, then ionic conductivity is improved, but structural stability may deteriorate
Solution Approach 1:
The patent applies local quality by creating localized regions of different dopant concentrations within the crystal structure. The dual-doping scheme M1xM2y allows for spatial distribution where M1 (alkaline earth metal) provides structural stabilization while M2 (alkali/transition metal) contributes to vacancy formation and conductivity enhancement. This local differentiation resolves the contradiction between stability and conductivity.
Solution Approach 2:
The patent optimizes the stoichiometry parameters x and y to achieve an optimal balance between fluorine vacancy concentration and structural stability. By controlling the ratios of different dopants and their absolute concentrations within specific ranges, the material achieves sufficient ionic conductivity while maintaining crystal structure integrity, preventing excessive lattice distortion.
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 material achieves high fluoride ion conductivity at room temperature, enabling fluoride shuttle batteries to operate effectively and efficiently at ambient conditions, with enhanced charge/discharge capacities and energy density.
Implementation Method 1
Fluoride ion conductive material including a compound containing fluorine element, lanthanum element, an alkaline earth metal element, and an alkali metal element
Implementation Method 2
enhancing fluoride ion conductivity at room temperature by increasing fluorine vacancies in the lanthanum fluoride crystal
Data Source
AI summary
A fluoride ion conductive material includes a compound containing fluorine element, lanthanum element, an alkaline earth metal element, and an alkali metal element. The compound is represented by La1-x-yM1xM2yF3-x-2y wherein M1 is at least one element selected from alkaline earth metal elements, M2 is at least one element selected from alkali metal elements, x satisfies 0<x≤0.3, y satisfies 0<y≤0.2, and x+y satisfies 0<x+y≤0.4.