End-of-life lithium-ion batteries retired from portable electronics, electric vehicles (EVs), and power grids need to be properly recycled to save rare earth metals and avoid any hazardous threats to the environment. The recycling process of a Lithium-ion Battery Cell/Module includes storage, transportation, deactivation, disassembly, and material recovery. This study focused on the disassembly step and proposed a systematic method to recover cathode active coating, which is considered the most valuable component of a LIB, from end-of-life LIB pouch cells. A semi-destructive disassembly sequence is developed according to the internal structure of the LIB cell. A fully automated disassembly line aiming at extracting cathode electrodes is designed, modeled, prototyped, and demonstrated based on the disassembly sequence. In order to further obtain the coating material, the extracted cathode electrodes are treated with the organic solvent method and the relationship between process parameters and cathode coating separation yield is numerically studied with the help of Design of Experiment (DOE). Regression models are then fitted from the DOE result to predict the cathode coating separation yield according to combinations of the process parameters. The single cell material separation methodology developed in this study plays an important role in the industrial application of the direct recycling method that may dominate the battery recycling market due to its environmental friendly technology and high recovery rate regardless of element type in the short future. / Doctor of Philosophy / The bursting demand of lithium-ion batteries from portable electronics, electric vehicles, and power grids in the past few years not only facilitate the booming of the lithium-ion battery market, but also put forward serious global concerns: Where should these batteries go at their end-of life and how should they be treated in a safe and harmless manner. As a metal enriched "city mine", end-of-life LIBs are expected to be properly stored, transported, deactivated, disassembled, and recovered with sufficient safety precautions to prevent fire, explosion or any hazardous emissions. This study focuses on the disassembly procedure and emphasized automated battery disassembly techniques and the improving of material separation efficiency. A disassembly sequence of the pouch cell is scheduled and optimized for the first time. To realize the scheduled sequence, a fully automated pouch cell disassembly system is designed to achieve semi-destructive disassembly of z-folded pouch cells. Fixtures, transporters and end-effectors were prototyped and assembled into the modularized disassembly line which extracts cathode electrodes as final product. Cathode electrodes as the most valuable component in a LIB then need to go through multiple chemical-mechanical treatments to future separate cathode coating and Al current collector. This study utilized DOEs to optimize the operating parameters of the material separation process for Lithium cobalt oxide (LCO) coating and Lithium iron phosphate (LFP) coating. Regression models are successfully established for yield prediction with certain levels of control factors.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/100735 |
| Date | 27 October 2020 |
| Creators | Li, Liurui |
| Contributors | Mechanical Engineering, Li, Zheng, Aning, Alexander O., Qiao, Rui, Ellis, Michael W. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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