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A Systematic Strategy to Enhance the Performance of Advanced Cobalt-free Cathode Materials for Li-ion Batteries.

Jiao, Xinwei
http://rave.ohiolink.edu/etdc/view?acc_num=osu1720547024165643

Abstract Details

2024, Doctor of Philosophy, Ohio State University, Mechanical Engineering.
To meet the growing demands of electric vehicles and energy storage devices, it is essential to develop advanced lithium-ion batteries (LIBs) that not only provide high energy density but also affordability and rapid charging and discharging capabilities. Cathode materials account for over 40% of the total cost of a battery and directly determine the battery's voltage and capacity. Therefore, it is imperative to develop low-cost cathode materials with high electrochemical performance. In this dissertation, we explored several cobalt-free cathode materials, including spinel-structured LiNi0.5Mn1.5O4 (LNMO), nickel-rich cobalt-free LiNi0.95M0.05O2 (M=Al, Mn, Mg, and Ti) layered oxides and xLi2MnO3·(1 – x)LiMO2 (M = Ni and Mn) layered oxides (LMR), which have the advantage of low raw materials price compared to commercialized cathode materials, such as LiCoO2 and cobalt-rich LiNi0.33Co0.33Mn0.33O2 (NMC111) layered oxides. However, like most cathode materials, they also encounter significant challenges, including low thermal stability, an unstable internal structure, and rapid capacity fading, which is caused by serious anisotropic volume changes during cycling, continuous electrolyte decomposition, and transition metal dissolution, particularly at high operating voltages. To overcome these challenges, we present three advanced strategies aimed at producing intergranular-crack-free cathode materials with superior cycling performance, high internal structure stability, and minimal parasitic reactions even under severe cycling conditions. Firstly, employing solid-state electrolytes as Li-ion conductors to form a stable cathode electrolyte interphase (CEI) layer. Secondly, establishing a concentration-gradient layered oxide with a Ni-rich core and an enrichment of substituted elements in the surface region through a co-precipitation reactor. The presence of a Ni-rich core enhances the material's capacity, while the transition elements at the surface ensure excellent cyclability and thermal stability. The concentration-gradient structure effectively mitigates side reactions between the interphase of the electrode and electrolyte and reduces volume changes during the high lithium extraction process, thereby minimizing capacity decline after long-term cycling. Finally, fabrication of single crystal layered oxide cathodes, which can offer high structural integrity and reduced interface interactions with the electrolyte. Herein, we will use mechanochemistry methods to form ideal single-crystal morphology layered oxide cathode materials without prolonged high-temperature calcination or using excess lithium salt.
Jung-Hyun Kim, Dr. (Advisor)
Jay Sayre, Dr. (Committee Member)
Stephanie Stockar, Dr. (Committee Member)
Lei Raymond Cao, Dr. (Committee Member)
185 p.
Materials Science; Mechanical Engineering
Li-ion battery, Cathode materials, degradation, core-shell, single-crystal, solid-state electrolyte, mechanical stability, thermal stability

Recommended Citations

Citations

  • Jiao, X. (2024). A Systematic Strategy to Enhance the Performance of Advanced Cobalt-free Cathode Materials for Li-ion Batteries. [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1720547024165643

    APA Style (7th edition)

  • Jiao, Xinwei. A Systematic Strategy to Enhance the Performance of Advanced Cobalt-free Cathode Materials for Li-ion Batteries. 2024. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1720547024165643.

    MLA Style (8th edition)

  • Jiao, Xinwei. "A Systematic Strategy to Enhance the Performance of Advanced Cobalt-free Cathode Materials for Li-ion Batteries." Doctoral dissertation, Ohio State University, 2024. http://rave.ohiolink.edu/etdc/view?acc_num=osu1720547024165643

    Chicago Manual of Style (17th edition)

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This open access ETD is published by The Ohio State University and OhioLINK.