國立虎尾科技大學 |

Nanomaterials for Energy Storage Devices and Electronic/Optoelectronic Devices.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Nanomaterials for Energy Storage Devices and Electronic/Optoelectronic Devices./
Author:	Shen, Chenfei.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2018,
Description:	147 p.
Notes:	Source: Dissertation Abstracts International, Volume: 79-06(E), Section: B.
Contained By:	Dissertation Abstracts International79-06B(E).
Subject:	Materials science. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=11016857

Nanomaterials for Energy Storage Devices and Electronic/Optoelectronic Devices.
Shen, Chenfei.

Nanomaterials for Energy Storage Devices and Electronic/Optoelectronic Devices. - Ann Arbor : ProQuest Dissertations & Theses, 2018 - 147 p.

Source: Dissertation Abstracts International, Volume: 79-06(E), Section: B.

Thesis (Ph.D.)--University of Southern California, 2018.

Nanomaterials have been receiving great attention in the past decade due to their wide applications in numerous areas. Among all the applications, energy storage devices and electronic/optoelectronic devices are two of the most appealing topics. During my Ph.D. study, I conduct research on the two major topics: 1. Study of novel silicon (Si) nanostructures and their application as lithium-ion battery anode materials; 2. Electronic and optoelectronic device study of novel two-dimensional (2D) materials. This dissertation starts from a brief introduction to lithium-ion battery and 2D electronics/optoelectronics in Chapter 1. Chapter 2 to 5 report the work we have done in lithium-ion battery and 2D electronics/optoelectronics. Chapter 6 discusses the future work in both Si anode direction and 2D material photodetector direction. Chapter 2 reports the study of the lithiation behaviors of both porous Si nanoparticles and porous Si nanowires by in situ and ex situ transmission electron microscopy (TEM) and compare them with solid Si nanoparticles and nanowires. The in situ TEM observation reveals that the critical fracture diameter of porous Si particles reaches up to 1.52 -m, which is much larger than the previously reported 150 nm for crystalline Si nanoparticles and 870 nm for amorphous Si nanoparticles. After full lithiation, solid Si nanoparticles and nanowires transform to crystalline Li--Si- phase while porous Si nanoparticles and nanowires transform to amorphous Li-Si phase, which is due to the effect of domain size on the stability of Li--Si- as revealed by the first-principle molecular dynamic simulation. Ex situ TEM characterization is conducted to further investigate the structural evolution of porous and solid Si nanoparticles during the cycling process, which confirms that the porous Si nanoparticles exhibit better capability to suppress pore evolution than solid Si nanoparticles. The investigation of structural evolution and phase transition of porous Si nanoparticles and nanowires during the lithiation process reveal that they are more desirable as lithium-ion battery anode materials than solid Si nanoparticles and nanowires. Chapter 3 reports our study on Si-S full cells. The challenges in the Si S full cell integration is discussed, and a failure mechanism of Si S full cell is proposed, which is due to the spontaneous reaction between Si (and lithiated Si) and polysulfides. On this basis, we report one prototype of Si S full cells using lithiated Nafion coated porous Si as anode and sulfur as cathode, and our study on the functionality of Nafion in shielding Si from reaction with polysulfides. With optimized mass ratio between sulfur and silicon, the full cell yields specific capacity of 330 mAh/g and energy density of 590 Wh/kg after 100 cycles based on the total mass of sulfur and silicon. The achieved energy density is more than 2 times higher than commercially available lithium ion batteries. The investigation of issues in Si S full cell research and the proposed full cell prototype will shed light on the development of next generation lithium ion batteries. Chapter 4 reports the synthesis of low-cost hierarchical carbon-coated (HCC) Si using ball-milled Si as the starting material. The obtained particles prepared from different Si sources all show excellent cycling performance of over 1000 mAh/g after 1000 cycles. Interestingly, we observed in situ formation of porous Si and it is well confined in the carbon shell based on post-cycling characterization of the hierarchical carbon-coated metallurgical Si (HCC-M-Si) particles. In addition, lightweight and free-standing electrodes consisting of the HCC-M-Si particles and carbon nanofibers were fabricated, which achieved 1015 mAh/g after 100 cycles based on the total mass of the electrodes. Compared with conventional electrodes, the lightweight and free-standing electrodes significantly improve the energy density by 745%. Furthermore, LiCoO- and LiNi-.-Mn-.-O- cathodes were used to pair up with the HCC-M-Si anode to fabricate full cells. With LiNi-.-Mn-.-O- as cathode, energy density up to 547 Wh/kg was achieved by the high-voltage full cell. After 100 cycles, the full cell with LiNi-.-Mn-.-O- cathode delivers 46% more energy density than that of the full cell with LiCoO- cathode. The systematic investigation on low-cost Si anodes together with their applications in lightweight free-standing electrodes and high-voltage full cells will shed light on development of high-energy Si-based lithium-ion batteries for real applications. Chapter 5 studies the novel 2D material black arsenic phosphorus (b-As-P---) formed by introducing arsenic into black phosphorus, which can significantly extend the operational wavelength range of photonic devices. The as-fabricated b-As-P--- photodetector sandwiched within hexagonal boron nitride (hBN) shows peak extrinsic responsivity of 190, 16, and 1.2 mA/W at 3.4, 5.0, and 7.7 -m at room temperature, respectively. Moreover, the intrinsic photoconductive effect dominates the photocurrent generation mechanism due to the preservation of pristine properties of b-As-P--- by complete hBN encapsulation and these b-As-P--- photodetectors exhibit negligible transport hysteresis. The broad and large photo-responsivity within mid-infrared resulting from the intrinsic photoconduction, together with the excellent long-term air stability, makes black arsenic phosphorus a promising alternative material for mid-infrared applications, such as free space communication, infrared imaging, and biomedical sensing. Chapter 6 proposes future research topics. To avoid the capacity loss of Si-based lithium-ion batteries in the first lithiation process, synthesis of Li-Si is highly desired. We propose a one-step large-scale synthesis method of Li-Si, which produces Li-Si and electrode slurry in a single step. Another research topic is Te photodetector. The application of black phosphorus and black arsenic phosphorus photodetector is limited because they are air-sensitive. As an air-stable two-dimensional material, Te also possesses similar electronic/optoelectronic properties as black phosphorus, which makes it promising candidate as medium-wavelength infrared photodetector. A systematic study of Te photodetector has been conducted and the underlying photocurrent generation mechanism is under investigation.Subjects--Topical Terms:

557839
Materials science.

Nanomaterials for Energy Storage Devices and Electronic/Optoelectronic Devices.
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Chapter 2 reports the study of the lithiation behaviors of both porous Si nanoparticles and porous Si nanowires by in situ and ex situ transmission electron microscopy (TEM) and compare them with solid Si nanoparticles and nanowires. The in situ TEM observation reveals that the critical fracture diameter of porous Si particles reaches up to 1.52 -m, which is much larger than the previously reported 150 nm for crystalline Si nanoparticles and 870 nm for amorphous Si nanoparticles. After full lithiation, solid Si nanoparticles and nanowires transform to crystalline Li--Si- phase while porous Si nanoparticles and nanowires transform to amorphous Li-Si phase, which is due to the effect of domain size on the stability of Li--Si- as revealed by the first-principle molecular dynamic simulation. Ex situ TEM characterization is conducted to further investigate the structural evolution of porous and solid Si nanoparticles during the cycling process, which confirms that the porous Si nanoparticles exhibit better capability to suppress pore evolution than solid Si nanoparticles. The investigation of structural evolution and phase transition of porous Si nanoparticles and nanowires during the lithiation process reveal that they are more desirable as lithium-ion battery anode materials than solid Si nanoparticles and nanowires. Chapter 3 reports our study on Si-S full cells. The challenges in the Si S full cell integration is discussed, and a failure mechanism of Si S full cell is proposed, which is due to the spontaneous reaction between Si (and lithiated Si) and polysulfides. On this basis, we report one prototype of Si S full cells using lithiated Nafion coated porous Si as anode and sulfur as cathode, and our study on the functionality of Nafion in shielding Si from reaction with polysulfides. With optimized mass ratio between sulfur and silicon, the full cell yields specific capacity of 330 mAh/g and energy density of 590 Wh/kg after 100 cycles based on the total mass of sulfur and silicon. The achieved energy density is more than 2 times higher than commercially available lithium ion batteries. The investigation of issues in Si S full cell research and the proposed full cell prototype will shed light on the development of next generation lithium ion batteries. Chapter 4 reports the synthesis of low-cost hierarchical carbon-coated (HCC) Si using ball-milled Si as the starting material. The obtained particles prepared from different Si sources all show excellent cycling performance of over 1000 mAh/g after 1000 cycles. Interestingly, we observed in situ formation of porous Si and it is well confined in the carbon shell based on post-cycling characterization of the hierarchical carbon-coated metallurgical Si (HCC-M-Si) particles. In addition, lightweight and free-standing electrodes consisting of the HCC-M-Si particles and carbon nanofibers were fabricated, which achieved 1015 mAh/g after 100 cycles based on the total mass of the electrodes. Compared with conventional electrodes, the lightweight and free-standing electrodes significantly improve the energy density by 745%. Furthermore, LiCoO- and LiNi-.-Mn-.-O- cathodes were used to pair up with the HCC-M-Si anode to fabricate full cells. With LiNi-.-Mn-.-O- as cathode, energy density up to 547 Wh/kg was achieved by the high-voltage full cell. After 100 cycles, the full cell with LiNi-.-Mn-.-O- cathode delivers 46% more energy density than that of the full cell with LiCoO- cathode. The systematic investigation on low-cost Si anodes together with their applications in lightweight free-standing electrodes and high-voltage full cells will shed light on development of high-energy Si-based lithium-ion batteries for real applications. Chapter 5 studies the novel 2D material black arsenic phosphorus (b-As-P---) formed by introducing arsenic into black phosphorus, which can significantly extend the operational wavelength range of photonic devices. The as-fabricated b-As-P--- photodetector sandwiched within hexagonal boron nitride (hBN) shows peak extrinsic responsivity of 190, 16, and 1.2 mA/W at 3.4, 5.0, and 7.7 -m at room temperature, respectively. Moreover, the intrinsic photoconductive effect dominates the photocurrent generation mechanism due to the preservation of pristine properties of b-As-P--- by complete hBN encapsulation and these b-As-P--- photodetectors exhibit negligible transport hysteresis. The broad and large photo-responsivity within mid-infrared resulting from the intrinsic photoconduction, together with the excellent long-term air stability, makes black arsenic phosphorus a promising alternative material for mid-infrared applications, such as free space communication, infrared imaging, and biomedical sensing. Chapter 6 proposes future research topics. To avoid the capacity loss of Si-based lithium-ion batteries in the first lithiation process, synthesis of Li-Si is highly desired. We propose a one-step large-scale synthesis method of Li-Si, which produces Li-Si and electrode slurry in a single step. Another research topic is Te photodetector. The application of black phosphorus and black arsenic phosphorus photodetector is limited because they are air-sensitive. As an air-stable two-dimensional material, Te also possesses similar electronic/optoelectronic properties as black phosphorus, which makes it promising candidate as medium-wavelength infrared photodetector. A systematic study of Te photodetector has been conducted and the underlying photocurrent generation mechanism is under investigation.
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