Abstract: Provided herein are energy storage device cathodes with high capacity electrochemically active material including compounds that include iron, fluorine, sulfur, and optionally oxygen. Batteries with active materials including a compound of the formula FeFaSbOc exhibit high capacity, high specific energy, high average discharge voltage, and low hysteresis, even when discharged at high rates. Iron, fluorine, and sulfur-containing compounds may be ionically and electronically conductive.

Abstract: Provided are methods of preparing a lithium ion cell including forming the cell by charging the lithium ion cell to at least about 5% or, more specifically, to at least about 20% of the theoretical capacity of the negative electrode electrochemically active material, holding the lithium ion cell in a charged state for at least about 0.5 hours, and discharging the lithium ion cell. Holding the lithium ion cell in a partially charged state is believed to significantly improve its Coulombic efficiency during subsequent cycling.

Abstract: Provided are conductive substrates having open structures and fractional void volumes of at least about 25% or, more specifically, or at least about 50% for use in lithium ion batteries. Nanostructured active materials are deposited over such substrates to form battery electrodes. The fractional void volume may help to accommodate swelling of some active materials during cycling. In certain embodiments, overall outer dimensions of the electrode remain substantially the same during cycling, while internal open spaces of the conductive substrate provide space for any volumetric changes in the nanostructured active materials. In specific embodiments, a nanoscale layer of silicon is deposited over a metallic mesh to form a negative electrode. In another embodiment, a conductive substrate is a perforated sheet with multiple openings, such that a nanostructured active material is deposited into the openings but not on the external surfaces of the sheet.

Abstract: Provided are novel electrolytes for use in rechargeable lithium ion cells containing high capacity active materials, such as silicon, germanium, tin, and/or aluminum. These novel electrolytes include one or more pyrocarbonates and, in certain embodiments, one or more fluorinated carbonates. For example, dimethyl pyrocarbonate (DMPC) may be combine with mono-fluoroethylene carbonate (FEC). Alternatively, DMPC or other pyrocarbonates may be used without any fluorinated carbonates. A weight ratio of pyrocarbonates may be between about 0% and 50%, for example, about 10%. Pyrocarbonates may be combined with other solvents, such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and/or ethyl-methyl carbonate (EMC). Alternatively, pyrocarbonates may be used without such solvents.

Abstract: Provided are novel electrode material composite structures containing high capacity active materials formed into porous base structures. The structures also include shells that encapsulate these porous base structures. During lithiation of the active material, the shell mechanically constrains the porous base structure. The shell allows lithium ions to pass through but prevents electrolyte solvents from interacting with the encapsulated active material. In certain embodiments, the shell contains carbon, while the porous base structure contains silicon. Although silicon tends to swell during lithiation, the porosity of the base structure and/or void spaces inside the shell helps to accommodate this additional volume within the shell without breaking it or substantially increasing the overall size of the composite structure.

Abstract: Provided are novel electrochemical cells that include positive electrodes, negative electrodes containing high capacity active materials such as silicon, and auxiliary electrodes containing lithium. An auxiliary electrode is provided in the cell at least prior to its formation cycling and is used to supply lithium to the negative electrode. The auxiliary electrode may be then removed from the cell prior or after formation. The transfer of lithium to the negative electrode may be performed using a different electrolyte, a higher temperature, and/or a slower rate than during later operational cycling of the cell. After this transfer, the negative electrode may remain pre-lithiated during later cycling at least at a certain predetermined level. This pre-lithiation helps to cycle the cell at more optimal conditions and to some degree maintain this cycling performance over the operating life of the cell. Also provided are methods of fabricating such cells.

Abstract: Provided are novel electrodes for use in lithium ion batteries. An electrode includes one or more intermediate layers positioned between a substrate and an electrochemically active material. Intermediate layers may be made from chromium, titanium, tantalum, tungsten, nickel, molybdenum, lithium, as well as other materials and their combinations. An intermediate layer may protect the substrate, help to redistribute catalyst during deposition of the electrochemically active material, improve adhesion between the active material and substrate, and other purposes. In certain embodiments, an active material includes one or more high capacity active materials, such as silicon, tin, and germanium. These materials tend to swell during cycling and may loose mechanical and/or electrical connection to the substrate. A flexible intermediate layer may compensate for swelling and provide a robust adhesion interface. Provided also are novel methods of fabricating electrodes containing one or more intermediate layers.

Abstract: Provided are conductive substrates having open structures and fractional void volumes of at least about 25% or, more specifically, or at least about 50% for use in lithium ion batteries. Nanostructured active materials are deposited over such substrates to form battery electrodes. The fractional void volume may help to accommodate swelling of some active materials during cycling. In certain embodiments, overall outer dimensions of the electrode remain substantially the same during cycling, while internal open spaces of the conductive substrate provide space for any volumetric changes in the nanostructured active materials. In specific embodiments, a nanoscale layer of silicon is deposited over a metallic mesh to form a negative electrode. In another embodiment, a conductive substrate is a perforated sheet with multiple openings, such that a nanostructured active material is deposited into the openings but not on the external surfaces of the sheet.

Abstract: Methods for compression molding through holes in polymer layers are provided, as are the resulting patterned polymer layers. Two key aspects of the invention are provision of a mold and substrate having different mechanical hardness, and provision of room for local flow of material. These aspects of the invention facilitate formation of through holes by compression molding that are not blocked or partially blocked by undesirable material. These polymer layers can be formed into three dimensional patterned structures by bonding patterned layers together. Since the layers include through holes, a three-dimensional polymer pattern can be formed. These patterned polymer layers and three dimensionally patterned polymer constructs have a wide variety of applications. For example, these constructs can be used for fabrication of micro-fluidic devices, and/or can be used for various medical and biological applications including drug delivery devices and tissue engineering devices.

Abstract: Multi-layered polymer devices having three-dimensional containers for holding a therapeutic and/or imaging agent are provided. The devices have a high loading ratio of agent to polymer material for effective treatment. Delivery wings or regions with channels connected to the containers are also incorporated in the devices. The delivery wings can be flexible and insertable into hollow instruments, such as a needle. Anchoring structures are also provided for fixing the position of the device after injection into a subject. The polymer layers of the device can be biodegradable. Biodegradable materials can also be used to provide controlled release of agents, such as for immunizations and other therapeutic or non-therapeutic applications.

Abstract: A silicon-based solid oxide fuel cell (SOFC) with high surface area density in a limited volume is provided. The structure consists of a corrugated nano-thin film electrolyte and a silicon supportive layer on a two-stage silicon wafer through-hole to maximize the electrochemically active surface area within a given volume. The silicon supportive layer is done by boron-etch stop technique with diffusion doping. The fabrication of two-stage wafer through hole combines deep reactive ionic etching (DRIE) and KOH wet etching of silicon for a wafer through hole containing two difference sizes. By these design and fabrication methods, the absolute electrochemically active area can be as high as five times of that of the projected area.

Abstract: Sensors and systems for electrical, electrochemical, or topographical analysis, as well as methods of fabricating these sensors are provided. The sensors include a cantilever and one or more probes, each of which has an electrode at its tip. The tips of the probes are sharp, with a radius of curvature of less than about 50 nm. In addition, the probes have a high aspect ratio of more than about 19:1. The sensors are suitable for both Atomic Force Microscopy and Scanning Electrochemical Microscopy.