Document Type

Thesis - Open Access

Award Date

2023

Degree Name

Master of Science (MS)

Department / School

Electrical Engineering and Computer Science

First Advisor

Xiaojun Xian

Keywords

3D host material, Carbon fiber cloth, Lithiophilicity design, Lithium metal batteries, Uniform lithium deposition

Abstract

Lithium metal is considered the Holy Grail for the anode for next-generation rechargeable batteries. Lithium metal has the highest theoretical capacity and lowest anode potential with respect to the standard hydrogen electrode (SHE). However, its commercialization is hindered by uncontrolled dendrite growth, weak solid electrolyte interphase (SEI), and low coulombic efficiency. The dendrite formation leads to a short circuit between the anode and cathode, which creates a dangerous safety issue. Several host materials and artificial SEI layers have been developed to suppress these issues. However, the effectiveness of these solutions is limited. More research is needed to develop more efficient and durable materials for better battery performance and safety. Herein, a lithium-infused carbon fiber matrix composite was developed by decorating NiO nanoparticles on carbon fiber and then infusing molten lithium. Strong bonding between carbon fibers and molten lithium was achieved with the help of NiO lithiophilic layer. The carbon fiber/lithium metal composite anode showed higher coulombic efficiency, stabler voltage profiles at high current densities, stabler SEI layer, and better specific capacity for a long duration than bare lithium anode. The NiO/Li/CF symmetrical cell at 0.5 mAcm-2, 3 mAcm-2, and 5 mAcm-2 current densities and 1 mAcm-2 specific capacity performs for 1400 hours, 200 hours, and 350 hours with a stable voltage profile and low voltage hysteresis without being short-circuited, which had been rarely achieved. The full cell with the as-prepared CF/Li composite anode with LiPF6 cathode performed for more than 250 cycles at 1C rate with an excellent and stable specific capacity of 130 mAh/g which was far better than the full cell with planer lithium metal anode. The large surface area and high conductivity of carbon fiber decrease the effective local current density. Highly lithiophilic NiO nanoparticles on carbon fiber helped to uniformly regulate the lithium-ion nucleation on the carbon fiber. Uniform striping/plating of lithium-ion proved a stable SEI layer and suppressed the formation of dendrites and volume change during high current densities. The simple synthesis approach and the outstanding cell performance suggest that the Li/NiO/CF nanocomposite could be an excellent candidate for advanced lithium metal batteries.

Publisher

South Dakota State University

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Rights Statement

In Copyright