Showing papers by "Xingcheng Xiao published in 2020"

Hierarchical porous silicon structures with extraordinary mechanical strength as high-performance lithium-ion battery anodes

Abstract: Porous structured silicon has been regarded as a promising candidate to overcome pulverization of silicon-based anodes. However, poor mechanical strength of these porous particles has limited their volumetric energy density towards practical applications. Here we design and synthesize hierarchical carbon-nanotube@silicon@carbon microspheres with both high porosity and extraordinary mechanical strength (>200 MPa) and a low apparent particle expansion of ~40% upon full lithiation. The composite electrodes of carbon-nanotube@silicon@carbon-graphite with a practical loading (3 mAh cm−2) deliver ~750 mAh g−1 specific capacity, 92% capacity retention over 500 cycles. This work is a leap in silicon anode development and provides insights into the design of electrode materials for other batteries. The authors here construct hierarchical porous CNT@Si@C microspheres as anodes for Li-ion batteries, enabling both high electrochemical performance and excellent mechanical strength. The work highlights the importance of mechanical properties in developing battery materials for practical applications.

The Bonding Nature and Adhesion of Polyacrylic Acid Coating on Li-Metal for Li Dendrite Prevention.

Abstract: The success of polyacrylic acid (PAA) to suppress Li dendrite growth suggests that the mechanical properties of polymer-based coatings, including the modulus, toughness, and interfacial adhesion are important design criteria. However, the measurement of the adhesion of thin PAA, as well as other polymer coatings to the reactive Li-metal anode surface is limited experimentally and challenging computationally. In this paper, a strategy was proposed to estimate the adhesion and delamination of the PAA(polymer)/Li interface, based on the bonding nature at the simpler PAA (oligomer)/Li interfaces using density functional theory calculations. It has been shown that the carboxylic acid groups in PAA reacted strongly with metallic Li, which significantly enhances the interfacial adhesion through the Li-O bonds formation, Li ionization and its incorporation into PAA, and -H or -OH termination of Li after decomposition of the COOH functional group. During delamination, it was found that the most likely PAA delamination route involved breaking partial Li-O bonds and lifting some ionized Li atoms from the Li-metal, especially for the Li atoms that showed a charge closer to +1 or are bonded with two O atoms from PAA. Based on the average bonding energies from PAA(oligomer)/Li interface delamination calculations, the work of separation, Wsep, of the PAA(polymer)/Li interface was estimated to be ∼1.0 (J/m2). The high Wsep of PAA (polymer)/Li was comparable with the Li2O/Li interface and higher than Li2CO3/Li and LiF/Li interfaces. This order correlated well with the areal density of Li-O bonds, which can serve as a descriptor for the interfacial adhesion. This computational approach can be applied to other interfaces with polymer-based coatings.

Electrodes and methods of fabricating electrodes for electrochemical cells by continuous localized pyrolysis

Abstract: A method of manufacturing a silicon-carbon composite electrode assembly for an electrochemical cell includes forming an electrode by pyrolyzing at least a portion of a polymer in an assembly to form pyrolyzed carbon. The assembly includes an electrode precursor in electrical contact with a current collector. The electrode precursor includes a polymer and an electroactive material. The electroactive material includes silicon. The current collector includes an electrically-conductive material. The pyrolyzing includes directing an energy stream toward a surface of the electrode precursor. The surface is disposed opposite the current collector. The silicon-carbon composite electrode assembly includes the electrode and the current collector. In certain variations, the energy stream includes a laser beam or a plasma jet. In certain aspects, the electrode defines a concentration gradient between a first surface and a second surface.

Protective coatings for lithium metal electrodes

Abstract: The invention relates to protective coatings for lithium metal electrodes Double-layered protective coatings for lithium metal electrodes, as well as methods of formation relating thereto, are provided The negative electrode assembly includes an electroactive material layer including lithium metal and a protective dual-layered coating The protective dual-layered coating includes a polymeric layer disposed on a surface of the electroactive material layer and an inorganic layer disposed on an exposed surface of the polymeric layer The polymeric layer has an elastic modulus of greater than orequal to about 001 GPa to less than or equal to about 410 GPa The inorganic layer has an elastic modulus of greater than or equal to about 10 GPa to less than or equal to about 1000 GPa

Laser-induced anti-corrosion micro-anchor structural layer for metal-polymeric composite joint and methods of manufacturing thereof

Abstract: A method of forming a layer on a first component according to various aspects of the present disclosure includes melting a portion of a first metallic composition of the first component. The melting includes directing a laser beam toward a first surface of the first component. The method further includes depositing a second metallic composition on the first surface by directing a precursor including the second metallic composition toward an intersection of the first surface and the laser beam. The second metallic composition is galvanically more noble than the first metallic composition. The method further includes forming the layer on the first component by solidifying the first metallic composition and the second metallic composition. The first component is configured to be joined to a second component by engaging a plurality of micro-anchors defined on the layer with a polymer of the second component.

Methods for preparing catalyst systems

Abstract: Methods for preparing a catalyst system, include providing a catalytic substrate comprising a catalyst support having a surface with a plurality of metal catalytic nanoparticles bound thereto and physically mixing and/or electrostatically combining the catalytic substrate with a plurality of oxide coating nanoparticles to provide a coating of oxide coating nanoparticles on the surface of the catalytic nanoparticles. The metal catalytic nanoparticles can be one or more of ruthenium, rhodium, palladium, osmium, iridium, and platinum, rhenium, copper, silver, and gold. Physically combining can include combining via ball milling, blending, acoustic mixing, or theta composition, and the oxide coating nanoparticles can include one or more oxides of aluminum, cerium, zirconium, titanium, silicon, magnesium, zinc, barium, lanthanum, iron, strontium, and calcium. The catalyst support can include one or more oxides of aluminum, cerium, zirconium, titanium, silicon, magnesium, zinc, barium, iron, strontium, and calcium.

Method for in situ growth of axial geometry carbon structures in electrodes

Abstract: Methods of forming a plurality of axial geometry carbon structures (e.g., carbon nanotubes or carbon fibers) in situ in an electrode of an electrochemical cell that cycles lithium ions are provided. Electroactive particles that undergo volumetric expansion are mixed with a polymer precursor and a plurality of catalytic nanoparticles comprising a metal selected from the group consisting of: iron, nickel, cobalt, alloys, and combinations thereof to form a substantially homogeneous slurry. The slurry is applied to a substrate and then heated in an environment having a temperature of ≤about 1000° C. and in certain aspects, ≤about 895° C. to pyrolyze the polymer precursor. The plurality of catalytic nanoparticles facilitates in situ precipitation of carbon to grow a plurality of axial geometry carbon structures. After the heating, the electrode includes an electrically conductive carbonaceous porous network comprising the plurality of electroactive particles and the plurality of axial geometry carbon structures.

Eliminierung von gasförmigen reaktanden in lithiumionenbatterien

Abstract: Eine Lithiumionen-Batterie ist vorgesehen, die eine positive Elektrode, eine negative Elektrode und einen zwischen der positiven Elektrode und der negativen Elektrode angeordneten Separator beinhaltet. Eines oder mehrere des Separators, der positiven Elektrode und der negativen Elektrode beinhalten eine Ubergangsmetallverbindung, die in der Lage ist, beliebige in der Lithiumionen-Batterie gebildete gasformige Reaktanden zu katalysieren, um eine Flussigkeit zu bilden. Die Ubergangsmetallverbindung kann Ruthenium (Ru) beinhalten. In bestimmten Variationen beinhaltet die Lithiumionen-Batterie einen Elektrolyten, der ein leitfahiges Medium fur Lithiumionen ist, um sich zwischen der positiven Elektrode und der negativen Elektrode zu bewegen. Der Elektrolyt umfasst eine Ubergangsmetallverbindung, die in der Lage ist, eine Reaktion beliebiger gasformiger Reaktanden zu katalysieren, um eine Flussigkeit zu bilden.

Smart multifunctional lens coatings

Abstract: Systems, methods and devices to inhibit sensing reduction in imperfect sensing conditions are described. A multifunctional coating superposing a lens includes a self-cleaning layer and a heating layer. The self-cleaning layer defines an external surface configured to be exposed to an exterior environment. The external surface defines three-dimensional surface features thereon. The three-dimensional surface features are adjacently disposed arcuate features that inhibit adhering of solid particles to the external surface and wetting of the external surface. The heating layer is in thermal communication with the external surface. The heating layer is selectively actuated to provide thermal energy to the external surface through resistive heating. Each of the self-cleaning layer and the heating layer is transparent to a predetermined wavelength of light.