Metal Composite Fluoride Cathodes for Stable Fluoride-Ion Capacity
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Solution Overview
Problem
Existing fluoride ion secondary batteries face challenges in achieving sufficient capacity and stability due to uncontrolled fluorination and defluorination reactions, leading to irreversible changes and decreased capacity.
Innovation Solution
The use of a metal composite fluoride represented by A x M1 y1 M2 y2 F z, where A is Mg, Ca, Sr, or Ba, and M1 and M2 are different transition metals, stabilizes the crystalline structure and enhances fluoride ion occlusion and release, allowing for higher capacity and controlled reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional fluoride ion secondary batteries use simple metal fluorides or single-metal composite fluorides, then the battery structure is simple and easy to manufacture, but the capacity is insufficient and structural collapse occurs during charge/discharge cycles
Solution Approach 1:
The patent applies composite materials by formulating a quaternary metal composite fluoride containing four different metals (alkali metal, alkaline earth metal, and two transition metals) in a specific ratio. This composite structure combines the advantages of different metals to achieve both high capacity and structural stability during fluoride ion occlusion and release cycles
Solution Approach 2:
The patent applies parameter changes by precisely controlling the compositional parameters (molar ratios of different metals) and synthesis parameters (temperature, atmosphere, time) to optimize the crystalline structure. The specific parameter range of 0.7≤x≤1.3 in the formula A x M1 y1 M2 y2 F z is critical for achieving stable charge/discharge performance
2Quantity of substance
If conventional fluoride ion secondary batteries use simple electrode materials, then the manufacturing process is simple, but uncontrolled fluorination and defluorination reactions lead to irreversible changes and decreased capacity
Solution Approach 1:
The quaternary metal composite fluoride acts as a composite material that provides controlled reaction pathways. The presence of multiple metals with different electrochemical properties creates a buffered system that regulates fluorination and defluorination reactions, preventing irreversible changes while maintaining high capacity
Solution Approach 2:
The patent applies intermediary by using the composite fluoride structure as a mediator between the electrode and electrolyte. The complex multi-metal structure serves as an intermediate layer that facilitates controlled ion transfer while preventing direct harmful interactions, ensuring reliable and reversible reactions
3Duration of action of moving object
If conventional fluoride ion secondary batteries use single-metal fluorides, then the electrode material is simple and cost-effective, but the charge/discharge performance is unstable due to structural collapse
Solution Approach 1:
The quaternary metal composite fluoride provides long-term charge/discharge stability through its composite structure. The multiple metal components work synergistically to maintain structural integrity during repeated fluoride ion occlusion and release, enabling stable cycling performance
Solution Approach 2:
The patent applies local quality by assigning different functional roles to different metal components within the composite. Each metal contributes specific local properties (e.g., structural framework, ion conduction pathways, electrochemical activity) that collectively enhance overall charge/discharge stability
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 metal composite fluoride exhibits a large capacity and stable charge/discharge performance by maintaining a stable electron state and suppressing structural collapse, thereby increasing the battery's operational efficiency.
Implementation Method 1
uncontrolled fluorination and defluorination reactions
Implementation Method 2
enhances fluoride ion occlusion and release
Implementation Method 3
stabilizes the crystalline structure and enhances fluoride ion occlusion and release
Implementation Method 4
suppressing structural collapse
Data Source
Figure 1~2
AI summary
An active material for a fluoride ion secondary battery includes a metal composite fluoride. The metal composite fluoride contains at least one metal selected from the group consisting of an alkali metal, an alkaline earth metal, scandium, yttrium, and a lanthanoid; a first transition metal; a second transition metal different from the first transition metal; and fluorine.