Cathode Active Material Recovery by Two-Phase Binder Separation
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Solution Overview
Problem
Conventional recycling methods for cathode active materials in lithium-ion batteries are inefficient, costly, and environmentally harmful, failing to effectively separate both large and small particles, and often require additional synthesis steps.
Innovation Solution
A two-phase separation method using a water-immiscible solvent to dissolve the binder, allowing for the separation of cathode active material particles from the binder, either through simple settling or with the aid of a stabilizer to form micelles, thereby recovering the active material without the need for re-synthesis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional recycling methods use large amounts of solvent to separate cathode active material from binder, then separation is achieved, but cost increases and environmental harm worsens
Solution Approach 1:
The patent changes the key parameter of solvent properties by selecting a solvent with specific characteristics: high boiling point, immiscibility with water, and ability to dissolve PVDF binder. This parameter optimization allows effective separation while reducing solvent consumption and environmental impact, as the solvent can be easily recovered and reused
Solution Approach 2:
The patent extracts and removes the binder from the cathode active material particles through selective dissolution in the chosen solvent. The binder is taken out of the mixture and separated into the solvent phase, leaving clean cathode active material particles in the aqueous phase
2Productivity
If conventional recycling methods separate large cathode active particles from binder, then some separation is achieved, but small particles remain mixed with binder reducing yield
Solution Approach 1:
The patent introduces water as an intermediary medium that does not dissolve the PVDF binder but provides a dispersion medium for both large and small cathode active material particles. This intermediary allows particles of all sizes to be separated from the binder while remaining suspended in the aqueous phase for complete recovery
3Ease of repair
If pyrometallurgical process is used to recycle batteries, then recycling is achieved, but lithium loss increases and cost increases
Solution Approach 1:
The patent replaces the thermal/mechanical pyrometallurgical process with a chemical dissolution process using a carefully selected solvent. This substitution allows selective dissolution of the binder at moderate temperatures without affecting the cathode active material particles, preventing lithium loss while achieving effective recycling
Solution Approach 2:
The patent changes the process parameters from high-temperature thermal processing to moderate-temperature chemical processing. The solvent is chosen to have appropriate solubility characteristics at these moderate temperatures, enabling binder removal while preserving the cathode active material and preventing lithium loss
4Quantity of substance
If hydrothermal processing with leaching agent is used, then metal precursors are recovered, but additional synthesis steps are required increasing complexity
Solution Approach 1:
The patent extracts only the binder component from the cathode structure while leaving the cathode active material particles intact and directly recoverable. This selective extraction eliminates the need to break down particles to metal precursors and re-synthesize them, reducing process complexity while maintaining recovery effectiveness
Solution Approach 2:
The patent performs preliminary separation of the binder before any particle breakdown or re-synthesis steps. By removing the binder first and recovering intact cathode active material particles, the process eliminates subsequent synthesis steps that would otherwise be required to reconstruct the active material
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
This method achieves high yield and cost-effective recovery of cathode active materials with minimal solvent use, reducing environmental impact and eliminating the need for additional synthesis steps.
Implementation Method 1
combining the binder, the cathode active material particles, water and a solvent, which is immiscible with water and dissolves the binder, in a vessel to form an emulsion of the two phases
Implementation Method 2
allowing the emulsion to settle and form a first phase and a second phase, and separating the first phase from the second phase. The first phase contains the solvent and the binder, and the second phase contains the water and the cathode active material particles
Data Source
AI summary
A method is provided for separating a binder from cathode active material particles. The method includes combining the binder, the cathode active material particles, water and solvent in a vessel to form a single phase. The method further includes allowing the single phase to settle and form a first phase and a second phase, and separating the first phase from the second phase. The first phase contains the solvent and the binder, and the second phase contains the water and the cathode active material particles.