Fluoride ion batteries are potential “next-generation” electrochemical storage devices that offer high energy density. At present, such batteries are limited to operation at high temperatures because suitable fluoride ion–conducting electrolytes are known only in the solid state. We report a liquid fluoride ion–conducting electrolyte with high ionic conductivity, wide operating voltage, and robust chemical stability based on dry tetraalkylammonium fluoride salts in ether solvents. Pairing this liquid electrolyte with a copper–lanthanum trifluoride (Cu@LaF3) core-shell cathode, we demonstrate reversible fluorination and defluorination reactions in a fluoride ion electrochemical cell cycled at room temperature. Fluoride ion–mediated electrochemistry offers a pathway toward developing capacities beyond that of lithium ion technology.
Recent reports on high capacity lithium ion batteries based on carbon nanostructures aroused expectations of realizing high energy density devices. We have studied the performances of a wide variety of carbon nanostructures with surface areas from a few up to 1400 m 2 /g as anode materials in Li-ion batteries by using three different experimental setups aiming to clarify the origin of high capacities. The obtained charge values consumed in the initial intercalation/deintercalation cycles of Li ions for high surface area nanostructures indeed correspond to capacities that exceed the theoretical limit for pristine graphite (372 Ah/kg; as LiC 6 ) up to a factor of six. Yet, typically these large excess capacity values were irreversibly diminished during further charge/discharge cycling. Density functional theory (DFT) calculations reveal a decisive role of edge carbon atoms in high surface nanostructures as active sites that contribute not only to an initial high capacity, but to the formation of a solid-electrolyte interphase and thereby to the irreversible capacity loss (ICL). These results question the feasibility of stable large excess Li capacity values in studied carbon nanostructures, yet suggest the design of nanostructures for reducing the ICL.For more than three decades, graphite has been the subject of intense research for Li-ion battery anodes due to its suitable properties and layered structure that allows intercalation/deintercalation of Liions without significantly compromising the overall battery durability. However, the specific capacity of Li ions in graphite is 372 Ah/kg (corresponding to the LiC 6 structure) and is limited by the peculiarities of the intercalation in the layered structure, Li clustering and phase separation processes. There have been a number of attempts to increase the Li storage capacity by exploiting modified graphite (for example, by varying flake diameter, pore size distribution, doping, and surface treatment), graphitic particles and disordered carbons, also called "soft" and "hard" carbons. 1-4 Various models, sometimes controversial, have been suggested in order to explain the high capacity values. For instance, the excess storage capacities have been explained by the existence of Li 2 covalent molecules that correspond to the Li 2 C 6 composition, 5 adsorption of Li at the graphite edges, 6 formation of LiC 2 in the carbon with larger interlayer spaces, 7 formation of a thin film of Li on the carbon surface, 8 or adsorption of Li on both sides of the graphene layer, the so-called "house of cards" model. 9 Nevertheless, up to this day the essential drawbacks for practical exploitation of graphitic carbon in Li-ion battery anodes are reproducibility and loss of the initial capacity during charge/discharge cycling. Indeed, studies have revealed strong correlations between the ICL and particle size, surface area and crystallinity. 10-14 In general, these previous studies have emphasized the importance of the ratio between the surface of the basal plane and the edge thickness...
Formation of organosilane monolayer templates using ultraviolet and electron-beam (EB) lithography was investigated. The oligonucleotides were covalently immobilized with high selectivity only to the amino-monolayer modified regions locally formed on the template surfaces at micro and nanometer scale. By using EB lithography, patterned immobilization in nanometer scale, as small as 20 nm, was achieved.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.