Browsing by Author "Li, Liurui"

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    The Material Separation Process for Recycling End-of-life Li-ion Batteries
    Li, Liurui (Virginia Tech, 2020-10-27)
    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.
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    Multiplexed Electrospray Emitters for Highly Conductive and Corrosive Fluids
    Li, Liurui (Virginia Tech, 2017-06-14)
    This thesis reports the design, fabrication, and operation of silicone based multiplexed electrospray (MES) emitters. After reviewing the feasibility of utilizing electrospray as a scalable thin film deposition technique as well as the advantages and limitations of prior MES emitters, we present a design rationale for MES suitable for highly conductive and corrosive fluids. Then we customized a 1064nm fiber laser micromachining system to precisely and rapidly machine silicone sheet and silicon wafers. Laser energy and path are judicially chosen to create clean and round micro posts that form the external structure of the nozzles. For MES with low flow rate per nozzle, it is of vital importance to evenly distribute the liquid into each nozzle on the entire MES array by controlling the pressure drop inside each fluid flow channel. To this end, we modeled the dimension of microfluidic channels that introduce flow impedance overwhelming surface tension at the nozzle tip. We presented laser microfabrication techniques for fabricating two typical types of microfluidic channels: the through-hole array on conductive silicone sheets and the in-plane microfluidic channel on silicon wafers. Next, we developed a convenient assemble process for the integration of three layers (distributor layer, extractor layer, and collector layer) of the MES emitter. The uniformity of the flow rate among nozzles on MES emitters was investigated by observing the overall spray profiles and measuring the diameter of each jet. The results suggest that the silicone-based MES emitters are feasible for spraying highly conductive and corrosive liquids. The MES emitter developed in this thesis may become a promising tool in the scalable manufacturing of thin film perovskite solar cells.
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    Parameter optimization and yield prediction of cathode coating separation process for direct recycling of end-of-life lithium-ion batteries
    Li, Liurui; Yang, Tairan; Li, Zheng (2021-07-21)
    Fast adoption of lithium-ion batteries (LIBs) for electric vehicles requires an effective LIB recycling process to recover the valuable battery components and alleviate the concerns over the disposal of hazardous waste. The retrieval efficiency of cathode materials in direct recycling of end-of-life (EOL) lithium-ion batteries is systematically studied using the Taguchi Design of Experiment (DoE) method for the first time. A mathematical regression model is also developed to predict the yield and guide the parameter selection.