Ni-Rich Lithium Cathode Preparation to Suppress Cation Mixing
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Solution Overview
Problem
Current secondary lithium batteries experience performance degradation due to the reduction of trivalent nickel ions to divalent nickel ions in Ni-rich positive electrode materials, leading to cation mixing and reduced battery performance.
Innovation Solution
A preparation method involving the mixing of a compound with ethylenically-unsaturated and carbonyl groups, such as maleimide or acrylate-based compounds, with Ni-rich oxide of lithium and transition metals to prevent the reduction of trivalent nickel ions, thereby reducing cation mixing and enhancing battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nickel content in transition metal is increased to achieve higher energy density, then battery energy density is improved, but trivalent nickel ions are reduced to divalent nickel ions causing cation mixing and battery performance degradation
Solution Approach 1:
The patent introduces a fluorinated compound as an intermediary substance that reacts with nickel ions to form a protective interface layer. This intermediary layer prevents direct contact between divalent nickel ions and lithium ions, thereby preventing cation mixing while allowing the high nickel content to be maintained for energy density improvement.
Solution Approach 2:
The patent changes the chemical state of the interface by introducing fluorinated compounds that modify the surface chemistry of the positive electrode material. This parameter change in the interface composition prevents the reduction of trivalent nickel ions to divalent nickel ions, thereby maintaining battery performance stability even with high nickel content.
2Quantity of substance
If Ni-rich oxide is used to achieve high energy density, then battery energy density is improved, but LiNiO2 forms and reacts with water vapor and carbon dioxide causing battery performance degradation
Solution Approach 1:
The patent converts the harmful reaction between LiNiO2 and environmental gases into a beneficial protective mechanism. By introducing fluorinated compounds, the patent creates a stable interface layer that not only prevents harmful reactions but also enhances the overall stability of the Ni-rich oxide material, turning the potential harm into a benefit for long-term battery performance.
3Quantity of substance
If trivalent nickel ions are reduced to divalent nickel ions, then battery energy density may be increased, but cation mixing occurs causing battery performance degradation
Solution Approach 1:
The fluorinated compound acts as an intermediary barrier that physically separates cations of different valences. This intermediary layer prevents the migration and mixing of divalent nickel ions with lithium ions, thereby maintaining cation distribution stability even when divalent nickel ions are present in the structure.
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 method effectively increases the capacitance and reversibility of lithium batteries by preventing the reduction of trivalent nickel ions, thereby reducing battery performance degradation and improving overall battery performance.
Implementation Method 1
mixing a compound containing at least one ethylenically-unsaturated group and one carbonyl group or a derivative thereof and a Ni-rich oxide of lithium and transition metal to react
Data Source
AI summary
A preparation method of a positive electrode material of a lithium battery is provided, including mixing a compound containing at least one ethylenically-unsaturated group and one carbonyl group or a derivative thereof and a Ni-rich oxide of lithium and transition metal to react. The compound containing at least one ethylenically-unsaturated group and one carbonyl group is selected from a group consisting of a maleimide-based compound, an acrylate-based compound, a methacrylate-based compound, an acrylamide-based compound, a vinylamide-based compound, and a combination thereof, and the Ni-rich oxide of lithium and transition metal is represented by formula I,LiNixMyO2 Formula Iwherein x+y=1, 1>x≥0.5, and M is at least one transition metal element except Ni.