Nano-Engineering of Densely Packed Electrochemical Energy Storage Architectures by Atomic Layer Deposition

Nanostructures are highly attractive for future electrical energy storage devices because they enable large surface area and short ion transport time through thin electrode layers for high power devices. Significant enhancement in power density of batteries has been achieved by nano-engineered structures, particularly anode and cathode nanostructures spatially separated far apart by a porous membrane and/or a defined electrolyte region. A self-aligned nanostructured battery fully confined within a single nanopore presents a powerful platform to determine the rate performance and cyclability limits of nanostructured storage devices. Atomic layer deposition (ALD) has enabled us to create and evaluate such structures, comprised of nanotubular electrodes and electrolyte confined within anodic aluminum oxide (AAO) nanopores. The V2O5- V2O5 symmetric nanopore battery displays exceptional power-energy performance and cyclability when tested as a massively parallel device (~2billion/cm2), each with ~1m3 volume (~1fL). Cycled between 0.2V and 1.8V, this full cell has capacity retention of 95% at 5C rate and 46% at 150C, with more than 1000 charge/discharge cycles. These results demonstrate the promise of ultrasmall, self-aligned/regular, densely packed nanobattery structures as a testbed to study ionics and electrodics at the nanoscale with various geometrical modifications and as a building block for high performance energy storage systems[1, 2]. Further increase of full cell output potential is also demonstrated in asymmetric full cell configurations with various low voltage anode materials. The asymmetric full cell nanopore batteries, comprised of V2O5 as cathode and prelithiated SnO2 or anatase phase TiO2 as anode, with integrated nanotubular metal current collectors underneath each nanotubular storage electrode, also enabled by ALD. By controlling the amount of lithium ion prelithiated into SnO2 anode, we can tune full cell output voltage in the range of 0.3V and 3V. This asymmetric nanopore battery array displays exceptional rate performance and cyclability. When cycled between 1V and 3V, it has capacity retention of approximately 73% at 200C rate compared to 1C, with only 2% capacity loss after more than 500 charge/discharge cycles. With increased full cell output potential, the asymmetric V2O5-SnO2 nanopore battery shows significantly improved energy and power density. This configuration presents a more realistic test - through its asymmetric (vs symmetric) configuration – of performance and cyclability in nanoconfined environment. This dissertation covers (1) Ultra small electrochemical storage platform design and fabrication, (2) Electron and ion transport in nanostructured electrodes inside a half cell configuration, (3) Ion transport between anode and cathode in confined nanochannels in symmetric full cells, (4) Scale up energy and power density with geometry optimization and low voltage anode materials in asymmetric full cell configurations. As a supplement, selective growth of ALD to improve graphene conductance will also be discussed[3]. References: 1. Liu, C., et al., (Invited) A Rational Design for Batteries at Nanoscale by Atomic Layer Deposition. ECS Transactions, 2015. 69(7): p. 23-30. 2. Liu, C.Y., et al., An all-in-one nanopore battery array. Nature Nanotechnology, 2014. 9(12): p. 1031-1039. 3. Liu, C., et al., Improving Graphene Conductivity through Selective Atomic Layer Deposition. ECS Transactions, 2015. 69(7): p. 133-138.

Final Report of the Phase III Archaeological Investigations at the Dr. Upton Scott House (18AP18), Annapolis, Anne Arundel County, Maryland, 1998-1999

In the summers of 1998 and 1999, the Archaeology in Annapolis project carried out archaeological investigation at the eighteenth century Dr. Upton Scott House site (18AP18)located at 4 Shipwright Street in the historic district of Annapolis, Anne Arundel County, Maryland. The Upton Scott House is significant as one of only a few Georgian houses with remnants of its original plantation-inspired landscape still visible (Graham 1998:147). Investigation was completed in agreement with the owners of the historic property, Mr. and Mrs. Paul Christian, who were interested in determining the condition and arrangement of Dr. Upton Scott’s well-documented pleasure gardens. Betty Cosans’ 1972 Archaeological Feasibility Report, the first real archaeological study of the Upton Scott House site, guided the research design and recovery efforts. Cosans determined that testing and survey in the back and side yards of the Scott property would yield important information on the use and history of the property, including that of Scott’s famous gardens. Excavation units and trenches were placed within three separate areas of backyard activity on the site which included Area One: extant brick stables in the southwest of the property; Area Two: the brick foundations of a small outbuilding located in the northwest area of the site; and Area Three: the area of Scott’s formal gardens. The research design included an interest in recovering evidence of African-American spiritual practice and domestic life at the site. Also of significant importance was an analysis of Scott’s garden beds, concerning the order and layout. Also sought was an understanding of the change in perception and use of the backyard by the various owners of the property.