Amorphous Metal Oxide Matrix for FeF3 Battery Cathode
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Solution Overview
Problem
Non-aqueous secondary batteries with conventional positive electrode active substances like iron fluoride (FeF3) face issues with rate and cycle characteristics due to aggregation of metal compounds during charge and discharge, leading to unstable charge/discharge operations and low energy density.
Innovation Solution
A positive electrode active substance is developed by combining a metal or metal compound that undergoes conversion reactions with an amorphous metal oxide, such as V2O5, which minimizes aggregation and reduces overvoltage, thereby improving cycle and rate characteristics. This combination includes metals like Fe and amorphous metal oxides like V2O5, along with alkali metal salts to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If iron fluoride (FeF3) is used as positive electrode active substance, then theoretical capacitance is high (712 mAh/g), but polarization is large and rate characteristics are poor
Solution Approach 1:
The patent uses a composite material consisting of FeF3 particles dispersed in an amorphous metal oxide matrix (such as V2O5, MoO3, MnO2, TiO2, or NiO). This composite structure combines the high capacitance of FeF3 with the aggregation-preventing properties of the amorphous metal oxide, resolving the contradiction between high theoretical capacitance and poor rate characteristics.
Solution Approach 2:
The patent changes the physical state of the metal oxide from crystalline to amorphous form. This parameter change is crucial because the amorphous structure prevents aggregation of metal compounds during charge-discharge cycles, thereby improving rate characteristics while maintaining high capacitance.
2Stability of the object's composition
If conversion positive electrode is optimized by keeping crystalline V2O5 amount low (several wt %), then charge/discharge stability improves, but irreversible capacitance and overvoltage remain large
Solution Approach 1:
The patent changes the phase state of V2O5 from crystalline to amorphous. This parameter change fundamentally alters the material's properties: the amorphous structure prevents aggregation of metal compounds, reduces irreversible capacitance, and lowers overvoltage during charge, while maintaining charge/discharge stability.
Solution Approach 2:
The patent creates a composite where FeF3 is dispersed in an amorphous metal oxide matrix. This composite structure allows the amorphous metal oxide to minimize aggregation and reduce overvoltage, while the FeF3 provides high capacitance, thus resolving both stability and energy loss issues.
3Stability of the object's composition
If metal compounds are allowed to aggregate to increase crystallinity, then electrode state returns are improved, but cycle characteristics and rate characteristics remain low
Solution Approach 1:
The patent inverts the conventional approach by preventing aggregation through the amorphous structure. The amorphous metal oxide matrix restrains metal compound aggregation, allowing the electrode to return to its original state after each cycle, thereby improving both cycle characteristics and rate characteristics simultaneously.
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 proposed solution significantly improves the cycle and rate characteristics of non-aqueous secondary batteries by reducing irreversible capacitance and overvoltage, maintaining high energy density even after repeated charge/discharge cycles, and stabilizing voltage during discharge.
Implementation Method 1
the metal compounds derived from the electrodes are aggregated to increase the crystallinity and do not return to the original electrode state
Implementation Method 2
a metal or metal compound including the metal element M1 exhibiting a conversion reaction and/or a reverse conversion reaction
Data Source
AI summary
A positive electrode active substance for the non-aqueous secondary battery is provided. The positive electrode active substance includes a metal or a metal compound including the metal element M1 exhibiting a conversion reaction and/or a reverse conversion reaction, and an amorphous metal oxide of the metal element M2. M2 includes at least one metal element selected from the group consisting of V, Cr, Mo, Mn, Ti, and Ni.