Abstract:
Provided are novel multidimensional electrode structures containing high capacity active materials for use in rechargeable electrochemical cells. These structures include main support structures and multiple nanowires attached to the support structures and extending into different directions away from these supports. The active material may be deposited as a layer (uniform or non-uniform) surrounding the nanowires and, in certain embodiments, the main supports and even substrate. The active material layer may be sufficiently thin to prevent pulverization of the layer at given operating conditions. Interconnections between the electrode structures and/or substrate may be provided by overlaps formed during deposition of the active layer. Silicide-based nano wires structures may be formed on the main supports in a fluidized bed reactor by suspending the metal-containing main supports in a silicon-containing process gas. A layer of silicon may be then deposited over these silicide nanowires.
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:
A lithium ion battery electrode includes silicon nanowires used for insertion of lithium ions and including a conductivity enhancement, the nanowires growth-rooted to the conductive substrate.
Abstract:
This invention relates to a high speed packet switching controller in a telephone switching system which can suitably be applied to a packet controller having large capacity using a neural network chip and maximize the system performance by the optimized switching operation. The high speed packet switching controller comprises a row address decoder for decoding a weight raw address which is inputted thereto, a column address decoder for decoding a weight column address which is inputted thereto, a matrix array for providing the neural network using address signals provided from the row address decoder and column address decoder and outputing varied voltage in accordance with an external weight value, a neural network for producing a final crossbar switching control signal, an external input/output bus for transmitting an output signal of the neural network, and an internal neural data bus for transmitting the address signal output from the row address decoder and column address decoder to the matrix array.
Abstract:
An aqueous approach to synthesize capped SnS quantum dots (QDs) followed by optional capping molecule extension by attaching one or more extending molecules to the capping molecule via peptide bond formation at elevated temperature. The capped SnS QDs may have a capping molecule:Sn:S molar ratio of 16:3:1 to 16:12:1. A suspension of SnS QDs was heat-treated at 200° C. for 0.5-4 hrs. The obtained SnS QDs showed an NIR emission peak at 820-835 nm with an excitation wavelength at 690 nm. The as synthesized SnS QDs were found to have high positive zeta potential of ˜30 mV and thus were toxic to cells. By neutralizing the SnS QDs the cytotoxicity was reduced to an accepted level. The heat-treatment step can be obviated by adding a glycerol solution containing S2− anions and capping molecule to a glycerol solution of Sn2+ ions.
Abstract:
A lithium ion battery electrode includes silicon nanowires used for insertion of lithium ions and including a conductivity enhancement, the nanowires growth-rooted to the conductive substrate.
Abstract:
Provided are nanostructures containing electrochemically active materials, battery electrodes containing these nanostructures for use in electrochemical batteries, such as lithium ion batteries, and methods of forming the nanostructures and battery electrodes. The nanostructures include conductive cores, inner shells containing active materials, and outer shells partially coating the inner shells. The high capacity active materials having a stable capacity of at least about 1000 mAh/g can be used. Some examples include silicon, tin, and/or germanium. The outer shells may be configured to substantially prevent formation of Solid Electrolyte lnterphase (SEI) layers directly on the inner shells. The conductive cores and/or outer shells may include carbon containing materials. The nanostructures are used to form battery electrodes, in which the nanostructures that are in electronic communication with conductive substrates of the electrodes.
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 electrode layers for use in rechargeable batteries, such as lithium ion batteries, and related fabrication techniques. These electrode layers have interconnected hollow nanostructures that contain high capacity electrochemically active materials, such as silicon, tin, and germanium. In certain embodiments, a fabrication technique involves forming a nanoscale coating around multiple template structures and at least partially removing and/or shrinking these structures to form hollow cavities. These cavities provide space for the active materials of the nanostructures to swell into during battery cycling. This design helps to reduce the risk of pulverization and to maintain electrical contacts among the nanostructures. It also provides a very high surface area available ionic communication with the electrolyte. The nanostructures have nanoscale shells but may be substantially larger in other dimensions. Nanostructures can be interconnected during forming the nanoscale coating, when the coating formed around two nearby template structures overlap.
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. This allows integration of the composite structures into various types of battery electrodes and cycling high capacity active materials without damaging the electrodes' internal structures and deteriorating cycling characteristics of batteries.