Melilite-Type Oxide Electrode Material for Stable Fluoride-Ion Cycling
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Solution Overview
Problem
Conventional electrode active materials for fluoride ion batteries exhibit high overpotential and poor cycle performance and rate capability due to significant volumetric changes during fluorination-defluorination reactions, which limit their effectiveness.
Innovation Solution
A complex oxide with a melilite-type crystal structure is used as the electrode active material, featuring a layered structure that facilitates two-dimensional diffusion of fluoride ions, reducing volumetric changes and enhancing cycle performance and rate capability through redox reactions of anions coordinated to specific metal sites.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrode active materials are used for fluoride ion batteries, then the battery can operate with basic functionality, but the overpotential is high and cycle performance and rate capability are poor due to significant volumetric changes during fluorination-defluorination reactions
Solution Approach 1:
The patent changes the crystal structure parameter from conventional structures to a layered perovskite structure with specific compositional parameters (A1-x-yLaxM1-yO3-delta where M = Ti, Zr, or Hf). This structural parameter change enables the material to accommodate volumetric changes during fluorination-defluorination reactions, maintaining compositional stability and improving cycle performance while reducing overpotential.
Solution Approach 2:
The patent employs composite material design by creating a doped perovskite structure where multiple elements (lanthanum doping at A-site, transition metals Ti/Zr/Hf at B-site) are combined within a single crystal framework. This composite approach at the atomic level provides both structural stability and enhanced ionic conductivity, resolving the contradiction between maintaining composition stability and achieving reliable cycle performance.
2Productivity
If conventional electrode active materials are used for fluoride ion batteries, then the battery can function with basic charge-discharge capability, but the rate capability is poor due to significant volumetric changes during fluorination-defluorination reactions
Solution Approach 1:
The patent modifies the crystal structure parameters to a layered perovskite configuration with controlled oxygen deficiency (delta in A1-x-yLaxM1-yO3-delta). This parameter optimization creates faster ion diffusion pathways while maintaining structural integrity during rapid fluorination-defluorination cycles, thereby improving rate capability without sacrificing volumetric stability.
Solution Approach 2:
The layered perovskite structure introduces a dimensional advantage by creating two-dimensional diffusion pathways for fluoride ions within the layers. This dimensional change allows for faster ion transport (improved rate capability) while the extended three-dimensional framework maintains volumetric stability during charge-discharge operations.
3Use of energy by moving object
If conventional electrode active materials are used for fluoride ion batteries, then the battery can operate with basic energy storage function, but the overpotential is high due to significant volumetric changes during fluorination-defluorination reactions
Solution Approach 1:
The patent optimizes the crystal structure parameters (lanthanum content x, transition metal type, and oxygen deficiency delta) to achieve a balance between energy efficiency and structural stability. The layered perovskite structure with specific compositional parameters reduces the energy barrier for fluoride ion insertion/extraction (lowering overpotential) while the robust framework maintains volumetric stability during energy storage cycles.
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 melilite-type crystal structure complex oxide demonstrates improved cycle performance and rate capability, reducing overpotential and increasing capacity through efficient fluoride ion diffusion and redox reactions, thereby enhancing the overall performance of fluoride ion batteries.
Implementation Method 1
a complex oxide with a melilite-type crystal structure is used as the electrode active material, featuring a layered structure that facilitates two-dimensional diffusion of fluoride ions
Implementation Method 2
enhancing cycle performance and rate capability through redox reactions of anions coordinated to specific metal sites
Data Source
Figure 1~2
AI summary
Provided is an electrode active material for a fluoride ion battery. The electrode active material for a fluoride ion battery includes a complex oxide that comprises a melilite-type crystal structure. The complex oxide includes: a first metal atom that comprises at least one type selected from a first metal atom group; a second metal atom that comprises at least one type selected from a second metal atom group; a specific non-metal atom that comprises at least one type selected from a specific non-metal atom group; and at least an oxygen atom as the specific non-metal atom. The first metal atom group includes Li, Be, Na, Mg, K, Ca, Rb, Sr, Y, Cs, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Bi. The second metal atom group includes Al, Si, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Sn, Hf, Ta, W, Re, Os, Ir, Pt, and Au. The specific non-metal atom group includes O, F, N, S, and Cl.