Combined Effects of Montmorillonite Clay, Carbon Nanofiber, and Fire Retardant on Mechanical and Flammability Properties of Polyamide 11 Nanocomposites

This paper is focused on the development of polyamide 11 (PA11) nanocomposites with enhanced fire retardant (FR) properties for application in selective laser sintering (SLS). Test specimens of PA11 containing various percentages of intumescent FR additive, montmorillonite (MMT) clay, and carbon nanofiber (CNF) were prepared via the twin screw extrusion technique. The combined effects of MMT clay, CNF, FR additives on the mechanical and flammability properties of these PA11 nanocomposites are studied. Izod impact testing, tensile testing, and SEM analysis of are used to characterize mechanical properties. UL-94 and SEM analysis of char surfaces are used to characterize the flammability properties of these materials. Results are analyzed to determine any synergistic effects among the additives to the material properties of PA11.Mechanical Engineerin

Development of antimony-based anode systems for lithium-ion batteries

textThe superior energy storage characteristics of lithium-ion batteries have made them the state-of-the-art battery technology for the past two decades where they have been integral to the proliferation of portable electronics. Efforts to expand their application into the realms of transportation and stationary storage require additional performance enhancements, though. These enhancements will be achieved through the application of advanced new materials such as alloy anodes like antimony. Alloy anodes offer the potential for dramatic enhancement of cell capacity both gravimetrically and volumetrically due to the high lithium content in their lithiated phases. Additionally, their higher operating voltage means that their incorporation should increase cell safety, a key parameter in large-scale applications, by reducing the risk of lithium plating. The primary factor inhibiting the adoption of alloy anodes is their short cycle life brought about by the large volume change they undergo during cycling that leads to crumbling of the active material and drastic capacity loss. To overcome this issue the following mitigation techniques are applied to antimony active materials: (i) use of active-material intermetallics of M[subscript x]Sb (where M = Ni or Fe) instead of pure antimony; (ii) incorporation of active material into reinforcing active/inactive composites with Al₂O₃, TiC, and/or carbon black; (iii) reduction of active material particles to nano-scale. In addition, the use of high-energy mechanical milling allows these methods to be applied with a simple and potentially scalable synthesis procedure and yields high-density final products. The actual safety performance of antimony anodes are also analyzed due to the importance of such parameters in large-battery applications. Because antimony alone without other components is an impractical anode material, the effects on safety and thermal stability of incorporating it into intermetallic and composite structures are also investigated. The advanced nanocomposites developed in this work demonstrate excellent cycle life with good all-around performance parameters that make them viable, safer candidates to replace graphite in next generation lithium-ion batteries. Pure antimony is also shown to offer enhancement in cell safety performance relative to graphite as well, and nanocomposites based upon its use as an active material are able to retain these favorable safety characteristics.Materials Science and Engineerin

Nanocomposite anode materials for sodium-ion batteries

The disclosure relates to an anode material for a sodium-ion battery having the general formula AOx—C or ACx—C, where A is aluminum (Al), magnesium (Mg), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), zirconium (Zr), molybdenum (Mo), tungsten (W), niobium (Nb), tantalum (Ta), silicon (Si), or any combinations thereof. The anode material also contains an electrochemically active nanoparticles within the matrix. The nanoparticle may react with sodium ion (Na+) when placed in the anode of a sodium-ion battery. In more specific embodiments, the anode material may have the general formula MySb-M′Ox—C, Sb-MOx—C, MySn-M′Cx—C, or Sn-MCx—C. The disclosure also relates to rechargeable sodium-ion batteries containing these materials and methods of making these materials.Board of Regents, University of Texas Syste

In Situ Mitigation of First-Cycle Anode Irreversibility in a New Spinel/FeSb Lithium-Ion Cell Enabled via a Microwave-Assisted Chemical Lithiation Process

First-cycle irreversibility is a major problem that plagues many next-generation nanoscale anode materials which form solid-electrolyte interphase (SEI) layers. Without a method to compensate for this irreversible capacity loss, the full cells will face serious problems. The concept of a lithium reservoir in spinel cathodes was proposed in the early 90s to combat the irreversibility of graphite anodes, but chemical techniques to lithiate spinel have been complex or hazardous. We present in this study (i) a new facile microwave-assisted chemical lithiation technique for spinel oxide cathodes which is capable of inserting one extra lithium per formula unit using less expensive, readily available lithium hydroxide in polyol and (ii) two new advanced lithium-ion batteries combining a prelithiated 5 V spinel Li_{1 + <i>x</i>}Mn_1.5Ni_0.5O₄ or a 4 V spinel Li_{1.05 + <i>x</i>}Ni_0.05Mn_1.9O₄ cathode and a carbon-free FeSb-TiC alloy anode that has a high first-cycle irreversible capacity loss. We show that the extra chemically inserted lithium is necessary to achieve a complete utilization of the cathode capacity. The battery employing the 5 V spinel cathode exhibits good rate capability with an energy density of 260 Wh/kg based on total active mass

Crystal structures of polymerized lithium chloride and dimethyl sulfoxide in the form of {2LiCl·3DMSO}n and {LiCl·DMSO}n

Two novel LiCl·DMSO polymer structures were created by combining dry LiCl salt with dimethyl sulfoxide (DMSO), namely, catena-poly[[chloridolithium(I)]-μ-(dimethyl sulfoxide)-κ2O:O-[chloridolithium(I)]-di-μ-(dimethyl sulfoxide)-κ4O:O], [Li2Cl2(C2H6OS)3]n, and catena-poly[lithium(I)-μ-chlorido-μ-(dimethyl sulfoxide)-κ2O:O], [LiCl(C2H6OS)]n. The initial synthesized phase had very small block-shaped crystals (0.20 mm) octahedron-shaped crystals formed. The plate crystals and the octahedron crystals are the same tetragonal structure with a 1 LiCl: 1 DMSO ratio. These structures are reported and compared to other known LiCl·solvent compounds