Browsing by Author "Rummeli, Mark H."
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- ItemDual‐Salt Electrolyte Additives Enabled Stable Lithium Metal Anode/Lithium–Manganese‐Rich Cathode Batteries(Weinheim : Wiley-VCH, 2021) Zhou, Junhua; Lian, Xueyu; Shi, Qitao; Liu, Yu; Yang, Xiaoqin; Bachmatiuk, Alicja; Liu, Lijun; Sun, Jingyu; Yang, Ruizhi; Choi, Jin-Ho; Rummeli, Mark H.Although lithium (Li) metal anode/lithium–manganese-rich (LMR) cathode batteries have an ultrahigh energy density, the highly active Li metal and structural deterioration of LMR can make the usage of these batteries difficult. Herein, a multifunctional electrolyte containing LiBF4 and LiFSI dual-salt additives is designed, which enables the superior cyclability of Li/LMR cells with capacity retentions of ≈83.4%, 80.4%, and 76.6% after 400 cycles at 0.5, 1, and 2 C, respectively. The dual-salt electrolyte can form a thin, uniform, and inorganic species-rich solid electrolyte interphase (SEI) and cathode electrolyte interphase (CEI). In addition, it alleviates the bulk Li corrosion and enhances the structural sustainability of LMR cathode. Moreover, the electrolyte design strategy provides insights to develop other high-voltage lithium metal batteries (HVLMBs) to enhance the cycle stability.
- ItemGraphene transfer methods: A review(New York, NY [u.a.] : Springer, 2021) Ullah, Sami; Yang, Xiaoqin; Ta, Huy Q.; Hasan, Maria; Bachmatiuk, Alicja; Tokarska, Klaudia; Trzebicka, Barbara; Fu, Lei; Rummeli, Mark H.Graphene is a material with unique properties that can be exploited in electronics, catalysis, energy, and bio-related fields. Although, for maximal utilization of this material, high-quality graphene is required at both the growth process and after transfer of the graphene film to the application-compatible substrate. Chemical vapor deposition (CVD) is an important method for growing high-quality graphene on non-technological substrates (as, metal substrates, e.g., copper foil). Thus, there are also considerable efforts toward the efficient and non-damaging transfer of quality of graphene on to technologically relevant materials and systems. In this review article, a range of graphene current transfer techniques are reviewed from the standpoint of their impact on contamination control and structural integrity preservation of the as-produced graphene. In addition, their scalability, cost- and time-effectiveness are discussed. We summarize with a perspective on the transfer challenges, alternative options and future developments toward graphene technology.
- ItemIn Situ Observations of Freestanding Single-Atom-Thick Gold Nanoribbons Suspended in Graphene(Weinheim : Wiley-VCH, 2020) Zhao, Liang; Ta, Huy Q.; Mendes, Rafael G.; Bachmatiuk, Alicja; Rummeli, Mark H.Bulk gold's attributes of relative chemical inertness, rarity, relatively low melting point and its beautiful sheen make it a prized material for humans. Recordings suggest it was the first metal employed by humans dating as far back to the late Paleolithic period ≈40 000 BC. However, at the nanoscale gold is expected to present new and exciting properties, not least in catalysis. Moreover, recent studies suggest a new family of single-atom-thick two-dimensional (2D) metals exist. This work shows single-atom-thick freestanding gold membranes and nanoribbons can form as suspended structures in graphene pores. Electron irradiation is shown to lead to changes to the graphene pores which lead to dynamic changes of the gold membranes which transition to a nanoribbon. The freestanding single-atom-thick 2D gold structures are relatively stable to electron irradiation for extended periods. The work should advance the development of 2D gold monolayers significantly. © 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
- ItemIn Situ Room Temperature Electron-Beam Driven Graphene Growth from Hydrocarbon Contamination in a Transmission Electron Microscope(Basel : MDPI, 2018-5-26) Rummeli, Mark H.; Pan, Yumo; Zhao, Liang; Gao, Jing; Ta, Huy Q.; Martinez, Ignacio G.; Mendes, Rafael G.; Gemming, Thomas; Fu, Lei; Bachmatiuk, Alicja; Liu, ZhongfanThe excitement of graphene (as well as 2D materials in general) has generated numerous procedures for the fabrication of graphene. Here we present a mini-review on a rather less known, but attractive, in situ means to fabricate graphene inside a transmission electron microscope (TEM). This is achieved in a conventional TEM (viz. no sophisticated specimen holders or microscopes are required) and takes advantage of inherent hydrocarbon contamination as a carbon source. Both catalyst free and single atom catalyst approaches are reviewed. An advantage of this technique is that not only can the growth process be imaged in situ, but this can also be achieved with atomic resolution. Moreover, in the future, one can anticipate such approaches enabling the growth of nano-materials with atomic precision.
- ItemOn the Catalytic Activity of Sn Monomers and Dimers at Graphene Edges and the Synchronized Edge Dependence of Diffusing Atoms in Sn Dimers(Weinheim : Wiley-VCH, 2021) Yang, Xiaoqin; Ta, Huy Q.; Hu, Huimin; Liu, Shuyuan; Liu, Yu; Bachmatiuk, Alicja; Luo, Jinping; Liu, Lijun; Choi, Jin-Ho; Rummeli, Mark H.In this study, in situ transmission electron microscopy is performed to study the interaction between single (monomer) and paired (dimer) Sn atoms at graphene edges. The results reveal that a single Sn atom can catalyze both the growth and etching of graphene by the addition and removal of C atoms respectively. Additionally, the frequencies of the energetically favorable configurations of an Sn atom at a graphene edge, calculated using density functional theory calculations, are compared with experimental observations and are found to be in good agreement. The remarkable dynamic processes of binary atoms (dimers) are also investigated and is the first such study to the best of the knowledge. Dimer diffusion along the graphene edges depends on the graphene edge termination. Atom pairs (dimers) involving an armchair configuration tend to diffuse with a synchronized shuffling (step-wise shift) action, while dimer diffusion at zigzag edge terminations show a strong propensity to collapse the dimer with each atom diffusing in opposite directions (monomer formation). Moreover, the data reveals the role of C feedstock availability on the choice a single Sn atom makes in terms of graphene growth or etching. This study advances the understanding single atom catalytic activity at graphene edges. © 2021 The Authors. Advanced Functional Materials published by Wiley-VCH GmbH
- ItemPhosphorus‐Based Composites as Anode Materials for Advanced Alkali Metal Ion Batteries(Hoboke, NJ : Wiley, 2020) Zhou, Junhua; Shi, Qitao; Ullah, Sami; Yang, Xiaoqin; Bachmatiuk, Alicja; Yang, Ruizhi; Rummeli, Mark H.Alkaline metal ion batteries, such as lithium‐ion batteries have been increasingly adopted in consumer electronics, electric vehicles, and large power grids because of their high energy density, power density and working voltage, and long cycle life. Phosphorus‐based materials including phosphorus anodes and metal phosphides with high theoretical capacity, natural abundance, and environmental friendliness show great potential as negative electrodes for alkaline metal ion batteries. In this review, based on the understanding of the storage mechanism of alkali metal ions, the scientific challenges are discussed, the preparation methods and solutions to address these challenges are summarized, the application prospects are demonstrated, and finally possible future research directions of phosphorus‐based materials are provided.
- ItemRapid synthesis of pristine graphene inside a transmission electron microscope using gold as catalyst([London] : Macmillan, 2019) Gonzalez-Martinez, Ignacio G.; Bachmatiuk, Alicja; Gemming, Thomas; Trzebicka, Barbara; Liu, Zhongfan; Rummeli, Mark H.Multiple methods with distinctive strengths and drawbacks have been devised so far to produce graphene. However, they all need post-synthesis transfer steps to characterize the product. Here we report the synthesis of pristine graphene inside the transmission electron microscope using gold as catalyst and self-removing substrate without employing a specialized specimen holder. The process occurs at room temperature and takes place within milliseconds. The method offers the possibility of precise spatial control for graphene production and immediate characterization. Briefly, the irradiating electrons generate secondary electrons leading to surface charging if the gold particles reside on a poorly conducting support. At a critical charge density, the particle ejects ions mixed with secondary electrons (plasma) causing the particle to shrink. Simultaneously, hydrocarbon contamination within the electron microscope is cracked, thus providing carbon for the growth of graphene on the particle’s surface. The Technique is potentially attractive for the manufacture of in situ graphene-based devices. © 2019, The Author(s).
- ItemRevealing the Various Electrochemical Behaviors of Sn4P3 Binary Alloy Anodes in Alkali Metal Ion Batteries(Weinheim : Wiley-VCH, 2021) Zhou, Junhua; Lian, Xueyu; You, Yizhou; Shi, Qitao; Liu, Yu; Yang, Xiaoqin; Liu, Lijun; Wang, Dan; Choi, Jin-Ho; Sun, Jingyu; Yang, Ruizhi; Rummeli, Mark H.Sn4P3 binary alloy anode has attracted much attention, not only because of the synergistic effect of P and Sn, but also its universal popularity in alkali metal ion batteries (AIBs), including lithium-ion batteries (LIBs), sodium-ion batteries (SIBs), and potassium-ion batteries (PIBs). However, the alkali metal ion (A+) storage and capacity attenuation mechanism of Sn4P3 anodes in AIBs are not well understood. Herein, a combination of ex situ X-ray diffraction, transmission electron microscopy, and density functional theory calculations reveals that the Sn4P3 anode undergoes segregation of Sn and P, followed by the intercalation of A+ in P and then in Sn. In addition, differential electrochemical curves and ex situ XPS results demonstrate that the deep insertion of A+ in P and Sn, especially in P, contributes to the reduction in capacity of AIBs. Serious sodium metal dendrite growth causes further reduction in the capacity of SIBs, while in PIBs it is the unstable solid electrolyte interphase and sluggish dynamics that lead to capacity decay. Not only the failure mechanism, including structural deterioration, unstable SEI, dendrite growth, and sluggish kinetics, but also the modification strategy and systematic analysis method provide theoretical guidance for the development of other alloy-based anode materials. © 2021 The Authors. Advanced Functional Materials published by Wiley-VCH GmbH