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Enhancing Energy Storage in the Solid Polymer Electrolyte within Li-ion Batteries and Li-S Batteries

Lopez Hallman, Raymond John
http://rave.ohiolink.edu/etdc/view?acc_num=akron1721834065716487

Abstract Details

2024, Doctor of Philosophy, University of Akron, Polymer Engineering.
Lithium-ion batteries (LIBs) are currently used in portable electronics because of their high specific capacity, voltage, cycle performance, and negligible self-discharge. However, their large-scale expansion is hindered by safety issues (thermal runaway) and insufficient energy density. To address LIB limitations, improvements are presented regarding solid polymer electrolytes (SPE), sulfur cathodes, and eutectic molten salts electrolytes (MSE). SPEs offer low flammability and high stability but suffer from low ionic conductivity. Our group developed a cross-linked PEGDA superionic conductive SPE, which exhibited a good ionic conductivity (above 1 mS/cm at 30 °C) and great electrochemical stability, but large-scale implementation remained a challenge. For this, a new aerosol jet-printed composite cathode was developed for a lithium metal battery that revealed an excellent performance, a specific capacity above 160 mAh/g at 60 °C and above 135 mAh/g at 30 °C with a high mass loading of 10 mg/cm2 containing LFP. Sulfur cathodes have a high specific capacity, theoretically, but significant drawbacks of low conductivity and volume expansion. Volume expansion was solved by melt-diffusing sulfur into porous Ketjen black. Conductivity improved by adding fluorinated graphite (CFx), which after chemical transformation remained carbon (of higher conductivity). Compared to the pure sulfur cathode, the hybrid cathode showed a higher specific capacity on the ratability test, and during long cycling, it had a stable capacity and a high specific capacity in the 200th cycle. The in-situ formation of a LiF protective layer was found to enhance cycling performance. MSE advantages are high conductivity and wide range in operating temperatures. However, MSE-based lithium batteries’ operative conditions are restricted within temperatures of 100-170 °C, limiting potential salts to use. The lithium nitrate based molten salt, Li0.46K0.54NO3, on a primary half-cell battery exhibited a low melting temperature (125 °C) and high ionic conductivity (88 mS/cm2). Coupled with CFx cathodes, they showed specific capacities that range from 580 mAh/g at 0.2C to 520.8 mAh/g at 10C, with consistent performances across several C-rates. To conclude, these works offer promising approaches of enhanced safety, stability, and performance to overcome current LIB limitations and pave the way for future advancements in battery technology.
Yu Zhu (Advisor)
Weinan Xu (Committee Chair)
Steven Chuang (Committee Member)
Aliaksei Boika (Committee Member)
Mark Soucek (Committee Member)
139 p.
Energy; Engineering; Materials Science; Plastics
Solid Polymer Electrolyte, 3D printing, Lithium, Sulfur battery, Eutectic Molten Salt and Enhance Energy Density

Recommended Citations

Citations

  • Lopez Hallman, R. J. (2024). Enhancing Energy Storage in the Solid Polymer Electrolyte within Li-ion Batteries and Li-S Batteries [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1721834065716487

    APA Style (7th edition)

  • Lopez Hallman, Raymond. Enhancing Energy Storage in the Solid Polymer Electrolyte within Li-ion Batteries and Li-S Batteries. 2024. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1721834065716487.

    MLA Style (8th edition)

  • Lopez Hallman, Raymond. "Enhancing Energy Storage in the Solid Polymer Electrolyte within Li-ion Batteries and Li-S Batteries." Doctoral dissertation, University of Akron, 2024. http://rave.ohiolink.edu/etdc/view?acc_num=akron1721834065716487

    Chicago Manual of Style (17th edition)

akron1721834065716487
© 2024, all rights reserved.
This open access ETD is published by University of Akron and OhioLINK.