We have used first-principles methods to investigate how metal atoms dispersed in the interlayer space of graphitic materials affect their hydrogen-binding properties. We have considered ideal stage-one metal-intercalated graphites of various compositions as representative model systems. Our calculations suggest that alkaline earth metals can significantly enhance the hydrogen storage properties: for example, Be and Mg atoms would act as binding sites of three or four hydrogen molecules, with binding energies per H$_2$ in the 0.2--0.7 eV range, as required for applications. We also find that alkali and transition metals are not as effective in enhancing the storage capacity.
Macroscopic arrays of highly crystalline nanocarbons offer the possibility of modifying the electronic structure of their low dimensional constituents, for example through doping, and studying the resulting collective bulk behaviour. Insertion of electron donors or acceptors between graphitic layers is an attractive method to reversibly increase charge carrier concentra-tion without disruption of the sp$2$-conjugated system. This work demonstrates FeCl$_{3}$ intercalation into fibres made up of collapsed (flattened) carbon nanotubes. The bundles of collapsed CNTs, similar to crystallites of gr…
First-principles calculations of the electronic structure and vibrational modes, in a system of graphene bilayers and trilayers intercalated with alkaline earth atoms, are resented. It is found that, in similarity to the case of superconducting graphite intercalation compounds, the Fermi level is crossed by an s-band derived from the intercalant states, as well as graphitic pi-bands. The electron-phonon coupling parameter is found to be 0.60 and 0.80, respectively, in calcium intercalated graphene bilayers and trilayers. In superconducting CaC6 graphite intercalation compound, the calculated v…
It has been a long-standing goal to create magnetism in a nonmagnetic material by manipulating its structure at the nanometer scale. This idea may be realized in graphitic carbon: evidence suggests magnetic states at the edges of graphene ribbons and at grain boundaries in graphite. Such phenomena have long been regarded as unlikely in silicon because there is no graphitic bulk phase. Here we show theoretically that intrinsic magnetism indeed exists in a class of silicon surfaces whose step edges have a nanoscale graphitic structure. This magnetism is intimately connected to recent observation…
Based on ab initio calculations, we examine the incorporation of Li atoms in the MoS2/graphene interface. We find that the intercalated Li atoms are energetically more stable than Li atoms adsorbed on the MoS2 surface. The intercalated atoms interact with both graphene sheet and MoS2 layer, increasing the Li binding energies. However, the equilibrium geometries are ruled by the MoS2 layer, where the intercalated Li atoms lie on the top (Li_T) and hollow (Li_H) sites of the MoS2 layer. We calculate the Li diffusion barriers, along the Li_T -> Li_H diffusion path, where we find similar energy ba…
In recent years intercalated and pillared graphitic systems have come under increasing scrutiny because of their potential for modern energy technologies. While traditional \emph{ab initio} methods such as the LDA give accurate geometries for graphite they are poorer at predicting physicial properties such as cohesive energies and elastic constants perpendicular to the layers because of the strong dependence on long-range dispersion forces. `Stretching' the layers via pillars or intercalation further highlights these weaknesses. We use the ideas developed by [J. F. Dobson et al, Phys. Rev. Let…
As a storage material for Li-ion batteries, graphene/molybdenum disulfide (Gr/MoS2) composites have been intensively studied in experiments. But the relevant theoretical works from first-principles are lacking. In the current work, van-der-Waals-corrected density functional theory calculations are performed to investigate the interaction of Li in Gr/MoS2 composites. Three interesting features are revealed for the intercalated Gr/Li(n)/MoS2 composites (n = 1 to 9). One is the reason for large Li storage capacity of Gr/MoS2: due to the binding energies per Li atom increase with the increasing nu…
We report on the hydrogen sorption investigation of the mixed alkali cluster intercalated fulleride series NaxLi6-xC60. These compounds are isostructural to Na6C60 and Li6C60 while the cubic lattice parameter is linearly dependent on x. The H2 absorption/desorption was studied by means of charge/discharge kinetic and coupled calorimetric - manometric measurements. By varying the stoichiometry, we found the best compromise between absorption rate, temperature and amount of hydrogen in Na1Li5C60. This system is able to reversibly absorb up to 4.3 wt% H2 at 280 °C, which is 70 °C lower in tempera…
A depth resolved investigation of hydrogen uptake in carbon based nanostructures by soft-to-hard photoemission spectroscopy
Università degli Studi di Roma Tre（罗马第三大学）；INFN Sezione di Roma Tre（罗马第三国立核物理研究所）；INFN Sezione di Roma（罗马国立核物理研究所）；Diamond Light Source Ltd（钻石光源有限公司）；University of Tsukuba（筑波大学）；Tsukuba Institute for Advanced Research (TIAR)（筑波高等研究院）
Two-dimensional (2D) materials are suitable hosts for the intercalation of extrinsic guest ions such as Li+, Na+ and K+ as the interlayer coupling is weak. This allows ion intercalation engineering of 2D materials, which may be a key to advancing technological applications in energy storage, neuromorphic electronics, and bioelectronics. However, ions that are extrinsic to the host materials possess challenges in fabrication of devices as there are extra steps of ion intercalation. This results in degradation of the long-term stability of the intercalated atomically thin structures. Here, we in…
Electron-doped magnetic Weyl semimetal LixCo3Sn2S2 by bulk-gating
RIKEN Center for Emergent Matter Science (CEMS)（RIKEN 新兴物质科学中心）；Department of Mechanical Engineering and Sciences, Kyoto University（京都大学机械工学与科学系）；Department of Physics, Tohoku University（东北大学物理学系）；Research Center for Advanced Science and Technology, The University of Tokyo（东京大学先进科学技术研究中心）；Quantum-phase Electronics Center and Department of Applied Physics, the University of Tokyo（东京大学量子相电子中心与应用物理系）
Influence of interstitial Li on the electronic properties of Li$_{x}$CsPbI$_{3}$ for photovoltaic and battery applications
University of Freiburg（弗赖堡大学）；Fraunhofer Institute for Mechanics of Materials IWM（弗劳恩霍夫材料力学研究所）；Freiburg Center for Interactive Materials and Bioinspired Technologies（弗赖堡互动材料与仿生技术研究中心）；Freiburg Materials Research Center（弗赖堡材料研究中心）
Pristine graphene interacts relatively weakly with Al, which is a specie of importance for novel generations of metal-ion batteries. We employ DFT calculations to explore the possibility of enhancing Al interaction with graphene. We investigate non-doped and N-doped graphene nanoribbons, address the impact of the edge sites, which are always present to some extent in real samples, and N-containing defects on the material's reactivity towards Al. The results are compared to that of pristine graphene. We show that introduction of edges does not affect the energetics of Al adsorption significantl…
Nonaqueous aluminum-ion batteries are an interesting emerging energy storage technology, offering a plethora of advantages over existing grid energy storage solutions. Carbonaceous and graphitic materials are an appealing cathode material in this system, thanks to their low cost and excellent rate capabilities. The phenomenon of poor Coulombic efficiency in the first cycle, however, is a known issue among some types of carbons, the reasons for which are yet to be fully understood. In this work, we propose that such processes are caused by the formation of a solid-electrolyte interphase, in a s…
Lithium-intercalated layered transition-metal oxides, LixTMO2, brought about a paradigm change in rechargeable batteries in recent decades and show promise for use in memristors, a type of device for future neural computing and on-chip storage. Thermal transport properties, although being a crucial element in limiting the charging/discharging rate, package density, energy efficiency, and safety of batteries as well as the controllability and energy consumption of memristors, are poorly managed or even understood yet. Here, for the first time, we employ quantum calculations including high-order…
Ubiquitous graphene is a stricly 2D material representing an ideal adsorbing platform due to its large specific surface area as well as its mechanical strength and resistance to both thermal and chemical stresses. However, graphene as a bulk material has the tendency to form irreversible agglomerates leading to 3D graphitic structures with a significant decrease of the area available for adsorption and no room for gas intercalation. In this paper a novel nanoporous graphite formed by graphtriyne sheets is introduced: its 3D structure is theoretically assessed by means of electronic structure a…
Grand Canonical Monte Carlo (GCMC) simulations are performed to study hydrogen physisorption in different nano carbon porous materials made up of different substructures including carbon nanotubes (CNT), graphene sheets and C60. Hydrogen weight percentage (wt%) at different temperatures with pressure ranging from 1 to 20MPa are predicted. Fugacity and quantum effects on hydrogen adsorption are investigated. Different structural dimensions including the sizes of the substructures and spacing between the substructures are used to study the geometrical effects on hydrogen storage capacity in carb…
Electric field enhances the electronic and diffusion properties of penta-graphene nanoribbons for application in lithium-ion batteries: a first-principles study
