Characterizing the influence of layered transition metal oxide morphology on cathode performance

Layered transition metal oxides are an important class of high energy density lithium-ion battery cathode materials. Because of their widespread use, it is important to elucidate factors that influence their stability in secondary battery applications. Using thick (>10 m), textured lithium cobalt oxide (LCO) cathodes, we reveal the impact of crystallographic orientation on the cycling stability of these layered transition metal oxide materials. We observe that (003) textured (LCO), (104) textured LCO, and composite LCO experience 48.5%, 65.9%, and 67.9% capacity fade after 100 cycles, respectively. Using electrochemical impedance spectroscopy, we measured the half-cell resistance to charge transfer and cathode electrolyte interphase resistance in 20 cycle increments. We detect that the charge transfer resistance grows 2280% for (003) LCO and 755% for (104) LCO, indicating that large regions of the textured cathodes crack during cycling. Conversely, we see that the growth of the cathode electrolyte interphase resistance of composite LCO cathode (95.3%) is much larger than what is observed for the textured LCO cathodes. The subsequent postmortem confocal Raman images confirm that state of charge heterogeneity is present in each cathode; interestingly, the extent of heterogeneity is correlated to the growth of the resistance to charge transfer. We continued to explore the impact of cathode morphology when studying single crystalline LiNi0.8Mn0.1Co0.1O2, a popular next generation cathode material. Fabrication of single crystals with a low initial cation mixing required optimization of the precursor flux. Using electrochemical impedance spectroscopy, we observed the interfacial changes for single crystals with predominately (012), (001), and (104) surface areas. From the obtained results it is calculated that the charge transfer resistance for (001), (012), and (104) dominant crystals grow 69.4%, 87.1%, and 14.5% in 65 cycles, respectively. Furthermore, we find that the cathode electrolyte interphase resistance for the (104) dominant single crystals only grows 3.82% in 65 cycles while this value grows 31.9% for (012) dominant single crystals in the same cycle range. Overall, the electrochemical results from this study support our assertion that cathodes with a predominately (104) surface area have stable interfacial properties, which make them attractive for long-term cycling. Moreover, our findings indicate that tailoring cathode microstructure is crucial to extending lithium-ion battery cycle life.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Materials Science & Engr

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2024

Author dc:creator

• Caple Jr., Michael Anthony

Contributors dc:contributor

• Braun, Paul V
• Miljkovic, Nenad
• Perry, Nicola H
• Krogstad, Jessica A

• Lithium-ion Batteries
• Layered Transition Metal Oxide Cathodes
• Molten Salt Synthesis
• Electrochemistry

Statement dc:rights

• Copyright 2024 Michael Caple Jr.

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/125578

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F125578