Cobalt-free cathode materials for Li-ion batteries: synthesis, processing, characterization and evaluation of the electrochemical performances
| dc.contributor.advisor | Ajayan, Pulickel | |
| dc.creator | Xu, Jianan | |
| dc.date.accessioned | 2023-08-09T19:25:51Z | |
| dc.date.created | 2023-05 | |
| dc.date.issued | 2023-04-20 | |
| dc.date.submitted | May 2023 | |
| dc.date.updated | 2023-08-09T19:25:51Z | |
| dc.description.abstract | Li-ion batteries cathode materials play an important role in limiting the overall capacity and energy density of the cell, due to their relatively lower specific capacity (~200 mAh/g) compared to that of the anode counterparts (Graphite 372 mAh/g, Si 4212 mAh/g). The chronological development of the classical cathode materials is reviewed. Li1.2Mn0.4Ti0.4O2 (LMTO) belonging to the emerged cation-disordered rock-salt cathodes family, is then selected due to its high specific capacity larger than 250 mAh/g and the Co-free inexpensive feature. While the typical cathode material loading is only 70.0 wt.% with additional components, a chemical vapor deposition method is applied to increase the electrical conductivity by coating a carbon layer on the LMTO particle surface. On the other hand, carbon nanotube is selected to be the ball milling additive and a 78.7 wt.% cathode loading is reached, which increases the cathode gravimetric capacity from 44 mAh/g to 121 mAh/g after fifty cycles. Li1.079Ni0.400Ti0.476O2 is then selected and ball-milled, and the PITT measurement is applied to extract the Li+ diffusivity value. The obtained DLi+ on the order of 10-15 cm2/s successfully explains the kinetic requirement for the particle size less than 200 nm, giving a 10 mA/g current density. Furthermore, the effects of ball milling on the electrochemical capacity and interfacial stability of Li2MnO3 cathode material is studied, which reveals the inducing of Li2CO3 contaminant species even though the capacity is largely enhanced, its further decomposition into CO2 during first charge and the reduction of CO2 to carbonate species during the following discharge. Next, an all-fluorinated electrolyte is coupled with the LMTO material which increases the coulombic efficiency to 90.0 % and 99.0 % for the first cycle and subsequent cycles, respectively, with a F-rich cathode-electrolyte-interphase characterized by XPS. Finally, several types of hydrothermal methods and a flash joule heating method are adopted to directly synthesize the LMTO material with nano-sized primary particles. As a result, spinel structure LiMnTiO4 is found to be the stable phase and LMTO can only be synthesized via traditional solid-state method. | |
| dc.embargo.lift | 2023-11-01 | |
| dc.embargo.terms | 2023-11-01 | |
| dc.format.mimetype | application/pdf | |
| dc.identifier.citation | Xu, Jianan. "Cobalt-free cathode materials for Li-ion batteries: synthesis, processing, characterization and evaluation of the electrochemical performances." (2023) Diss., Rice University. <a href="https://hdl.handle.net/1911/115195">https://hdl.handle.net/1911/115195</a>. | |
| dc.identifier.uri | https://hdl.handle.net/1911/115195 | |
| dc.language.iso | eng | |
| dc.rights | Copyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder. | |
| dc.subject | Li-ion cathode materials | |
| dc.subject | High specific capacity | |
| dc.subject | Ball milling treatment | |
| dc.subject | Carbon coating | |
| dc.subject | DEMS measurement | |
| dc.subject | All-fluorinated electrolyte | |
| dc.subject | Alternative synthetic methods | |
| dc.title | Cobalt-free cathode materials for Li-ion batteries: synthesis, processing, characterization and evaluation of the electrochemical performances | |
| dc.type | Thesis | |
| dc.type.material | Text | |
| thesis.degree.department | Materials Science and NanoEngineering | |
| thesis.degree.discipline | Engineering | |
| thesis.degree.grantor | Rice University | |
| thesis.degree.level | Doctoral | |
| thesis.degree.name | Doctor of Philosophy |
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