Dense Liquid Separation for Lithium-Ion Battery Electrode Recycling
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Solution Overview
Problem
Current methods for recycling lithium-ion battery materials, such as flotation separation, face challenges in efficiently separating anode and cathode active materials due to their similar morphology and the presence of polymer binders, leading to poor separation efficiency and potential damage to the materials.
Innovation Solution
A dense liquid separation process is employed, where the mixed electrode powder mixture is mixed with a high-density liquid whose density lies between that of the anode and cathode materials, allowing for effective separation without prior removal of binders, using liquids like bromoform or lithium metatungstates, and subsequent purification and regeneration for reuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If flotation separation is used to separate anode and cathode materials, then the separation process can be performed, but the separation efficiency is poor due to similar morphology and polymer binder presence
Solution Approach 1:
The patent changes the density parameter of the separation medium by using a dense liquid (such as bromoform or lithium metatungstate solution) with density between 2.0-4.5 g/cc, which is higher than both graphite anode material and metal oxide cathode material. This parameter change enables effective separation based on density differences rather than surface chemistry, resolving the poor separation efficiency issue.
Solution Approach 2:
The patent replaces the chemical/flotation-based separation mechanism with a physical density-based separation mechanism. Instead of relying on surface functionalization and bubble attachment (flotation), the system uses gravity-driven separation in a dense liquid medium, simplifying the process and improving efficiency.
2Reliability
If conventional flotation separation is used, then separation can be attempted, but the materials may be damaged due to poor separation efficiency and cross contamination
Solution Approach 1:
By changing to a dense liquid medium with controlled density between the anode and cathode materials, the patent achieves clean separation without the mechanical and chemical stresses of conventional flotation processes, preserving material integrity while improving separation efficiency.
3Manufacturing precision
If binder removal is performed prior to separation, then separation may be improved, but the process becomes more complex and time-consuming
Solution Approach 1:
The patent eliminates the need for preliminary binder removal by directly using the binder-containing black mass in the dense liquid separation process. The dense liquid medium allows separation to proceed effectively without prior binder removal, simplifying the overall process.
Solution Approach 2:
The patent extracts and removes the binder as a separate step after the main separation is complete, rather than requiring it to be removed before separation. This reverses the traditional sequence and simplifies the critical separation step.
4Productivity
If dense liquid separation is used, then efficient separation without binder removal is achieved, but high-density liquids may be expensive or require special handling
Solution Approach 1:
The patent provides flexibility in selecting the dense liquid medium, offering options ranging from expensive but effective bromoform to more economical lithium metatungstate solutions. The density parameter can be adjusted by changing concentration or selecting different compounds, allowing optimization between performance and cost.
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 enables efficient and cost-effective separation of anode and cathode materials without damaging them, allowing for high throughput and reuse in new lithium-ion batteries, while avoiding the need for complex or expensive equipment.
Implementation Method 1
mixing the harvested electrode active material mixture in a high density liquid whose density lies between those of the anode and cathode powders, respectively; allowing sufficient time so as to allow the anode, low-density fraction to float to the top of the liquid mixture and the cathode, high-density fraction to sink to the bottom
Implementation Method 2
The separation is accelerated in a centrifuge
Data Source
AI summary
Herein is disclosed a process for recycling electrode material from lithium-ion batteries, comprising harvesting a mixture of anode and cathode electrode materials from waste lithium-ion batteries, and separating the anode electrode material from the cathode electrode material by means of dense liquid separation. The mixed anode and cathode material is suspended in a liquid that has a density between those of the anode material and cathode material, such that the anode material rises to the top of the dense liquid and the cathode material sinks to the bottom of the dense liquid. The thus separated materials can easily be collected and further purified and regenerated for reuse in new lithium-ion batteries, providing an efficient and low-cost method for recycling electrode active materials from waste lithium-ion batteries.