Spent Cathode Active Material Defluorination Without Morphology Damage
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Solution Overview
Problem
Conventional methods for removing fluorine impurities from spent cathode active materials in lithium-ion batteries either destroy the material's structure or morphology, or require environmentally harmful solvents and high temperatures, and do not effectively remove metal fluorides.
Innovation Solution
A hydrothermal reaction with an alkaline solution containing an oxidative additive, followed by filtration and solid-phase relithiation, is used to remove fluorine impurities without damaging the cathode active material's structure, using sodium or potassium hydroxide to enhance fluorine removal efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thermal calcination is used to remove fluorine impurities, then fluorine removal is achieved, but the structure and morphology of the cathode active material are destroyed
Solution Approach 1:
The patent changes the chemical parameters of the treatment process by using alkaline solutions (NaOH, KOH, or LiOH) instead of high-temperature thermal treatment. This chemical approach removes fluorine impurities through dissolution and complexation reactions while maintaining the cathode material's structure and morphology intact
Solution Approach 2:
The patent introduces an intermediary substance (alkaline solution) that mediates the removal of fluorine impurities. The alkaline solution acts as a carrier that dissolves and removes metal fluorides from the cathode surface through chemical reactions, preventing direct thermal damage to the material structure
2Manufacturing precision
If conventional solvents like NMP or TEP are used to remove fluorine, then fluorine removal is achieved, but environmental harm and inability to remove metal fluoride occur
Solution Approach 1:
The patent replaces expensive and environmentally harmful conventional solvents (NMP, TEP) with inexpensive, environmentally benign alkaline solutions (NaOH, KOH, LiOH). These alkaline solutions can be easily disposed of or regenerated without causing environmental pollution, while effectively removing both organic and inorganic fluorine impurities
Solution Approach 2:
The patent changes the chemical composition parameters by using aqueous alkaline solutions instead of organic solvents. This parameter change enables the removal of metal fluoride impurities that conventional organic solvents cannot dissolve, while eliminating environmental pollution issues
3Manufacturing precision
If hydrothermal treatment at high temperature is used, then fluorine removal is achieved, but reaction time is long and morphology may be destroyed
Solution Approach 1:
The patent optimizes the temperature parameter by conducting the treatment at moderate temperatures (20-100°C) rather than high temperatures. This parameter change, combined with the use of strong alkaline solutions, achieves effective fluorine removal in shorter reaction times (0.5-12 hours) while preserving the cathode material's morphology
Solution Approach 2:
The patent uses excessive concentration of alkaline solutions to accelerate the fluorine removal reaction. By using concentrated alkaline solutions (e.g., 1-10 M NaOH), the reaction proceeds faster and more completely, reducing the required reaction time while maintaining effective fluorine removal
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 removes fluorine impurities while preserving the cathode active material's morphology and structure, enabling efficient recycling with minimal environmental impact.
Implementation Method 1
reacting the spent cathode active material with an alkaline solution to form a reaction mixture containing a metal fluoride
Implementation Method 2
filtering the reaction mixture to remove the metal fluoride
Implementation Method 3
drying the solid cathode active material particles
Data Source
AI summary
A method is provided for recycling a cathode active material. The method includes reacting spent cathode active material particles with an alkaline solution to form a reaction mixture containing a metal fluoride and solid cathode active material particles, and filtering the reaction mixture to remove the metal fluoride and separate the solid cathode active material particles from the reaction mixture. The method further includes mixing the solid cathode active material particles with a solid lithium material to form relithiated cathode active material particles, and heating the relithiated cathode active material particles to form the cathode active material. The alkaline solution comprises water and at least one hydroxide selected from the group consisting of: sodium hydroxide, potassium hydroxide and lithium hydroxide. The spent cathode active material particles comprise fluorine and lithium.