Solid-State Lithium Batteries with In Situ Polymerized Acrylate-Based Electrolytes Capable of Electrochemically Stable Operation at 100 °C.

Solid polymer electrolytes (SPEs) typically consist of salts with mobile anions that could cause instabilities and parasitic side reactions in solid-state lithium (Li) batteries. To address this challenge, single-Li-ion conducting (SLIC) SPEs, where anions of Li salts are covalently attached to the polymer backbone, have been utilized to reduce the number of mobile anions. This approach improves the cationic transference number but is accompanied by a loss of ionic conductivity.

Polyphosphazene-Based Anion-Anchored Polymer Electrolytes For All-Solid-State Lithium Metal Batteries.

Safety concerns of traditional liquid electrolytes, especially when paired with lithium (Li) metal anodes, have stimulated research of solid polymer electrolytes (SPEs) to exploit the superior thermal and mechanical properties of polymers. Polyphosphazenes are primarily known for their use as flame retardant materials and have demonstrated high Li-ion conductivity owing to their highly flexible P = N backbone which promotes Li-ion conduction via inter- and intrachain hopping along the polymer backbone. While polyphosphazenes are largely unexplored as SPEs in the literature, a few existing examples showed promising ionic conductivity.

Nanodiamond-Enhanced Nanofiber Separators for High-Energy Lithium-Ion Batteries.

Current lithium-ion battery separators made from polyolefins such as polypropylene and polyethylene generally suffer from low porosity, low wettability, and slow ionic conductivity and tend to perform poorly against heat-triggering reactions that may cause potentially catastrophic issues, such as fire. To overcome these limitations, here we report that a porous composite membrane consisting of poly(vinylidene fluoride--hexafluoropropylene) nanofibers functionalized with nanodiamonds (NDs) can realize a thermally resistant, mechanically robust, and ionically conductive separator. We critically reveal the role of NDs in the polymer matrix of the membrane to improve the thermal, mechanical, crystalline, and electrochemical properties of the composites.

Porous TiO/C Nanofibers with Axially Aligned Tunnel Pores as Effective Sulfur Hosts for Stabilized Lithium-Sulfur Batteries.

Hierarchically porous TiO/C nanofibers (NFs) with axially aligned cylindrical tunnel pore channels were synthesized as a sulfur (S) host for lithium-sulfur batteries (LSBs) by a microemulsion electrospinning method. We explored a synergistic chemical trapping reinforced by coordinatively unsaturated Ti nuclei with oxygen deficiency (or more broadly via polar O-Ti-O units) in combination with physical trapping in both narrow pores (<5 nm) and larger ordered pore tunnels (20-100 nm) separated by thin walls to allow for a large volume of active material and rapid diffusion within the channels while effectively blocking out the diffusion of soluble lithium polysulfides. Due to this unique architecture and enhanced conductivity, the prepared materials enabled a high S loading (∼72 wt %) and significantly reduced the shuttle effect.

Synthesis of Mg Alkoxide Nanowires from Mg Alkoxide Nanoparticles upon Ligand Exchange.

We report on a new synthesis pathway for Mg -propoxide nanowires (NWs) from Mg ethoxide nanoparticles using a simple alkoxy ligand exchange reaction followed by condensation polymerization in -propanol. In order to uncover the morphology-structure correlation in the metal alkoxide family, we employed a powerful range of state-of-the-art characterization techniques. The morphology transformation from nanoparticles to nanowires was demonstrated by time-lapse SEM micrographs.

High-Temperature Oxidation of Single Carbon Nanoparticles: Dependence on the Surface Structure and Probing Real-Time Structural Evolution via Kinetics.

O oxidation and sublimation kinetics for >30 individual nanoparticles (NPs) of five different feedstocks (graphite, graphene oxide, carbon black, diamond, and nano-onion) were measured using single-NP mass spectrometry at temperatures () in the 1100-2900 K range. It was found that oxidation, studied in the 1200-1600 K range, is highly sensitive to the NP surface structure, with etching efficiencies (EE) varying by up to 4 orders of magnitude, whereas sublimation rates, significant only for ≥ ∼1700 K, varied by only a factor of ∼3. Its sensitivity to the NP surface structure makes O etching a good real-time structure probe, which was used to follow the evolution of the NP surface structures over time as they were either etched or annealed at high .

Iron Phosphide Confined in Carbon Nanofibers as a Free-Standing Flexible Anode for High-Performance Lithium-Ion Batteries.

Iron phosphide with high specific capacity has emerged as an appealing candidate for next-generation lithium-ion battery anodes. However, iron phosphide could undergo conversion reactions and generally suffer from a rapid capacity degradation upon cycling due to its structure pulverization. Chemomechanical breakdown of iron phosphide due to its rigidity has been a challenge to fully realizing its electrochemical performance.

Electrolyte melt infiltration for scalable manufacturing of inorganic all-solid-state lithium-ion batteries.

All-solid-state lithium (Li) metal and lithium-ion batteries (ASSLBs) with inorganic solid-state electrolytes offer improved safety for electric vehicles and other applications. However, current inorganic ASSLB manufacturing technology suffers from high cost, excessive amounts of solid-state electrolyte and conductive additives, and low attainable volumetric energy density. Such a fabrication method involves separate fabrications of sintered ceramic solid-state electrolyte membranes and ASSLB electrodes, which are then carefully stacked and sintered together in a precisely controlled environment.

Boosting High-Performance in Lithium-Sulfur Batteries via Dilute Electrolyte.

Polysulfide shuttle effects, active material losses, formation of resistive surface layers, and continuous electrolyte consumption create a major barrier for the lightweight and low-cost lithium-sulfur (Li-S) battery adoption. Tuning electrolyte composition by using additives and most importantly by substantially increasing electrolyte molarity was previously shown to be one of the most effective strategies. Contrarily, little attention has been paid to dilute and super-diluted LiTFSI/DME/DOL/LiNO based-electrolytes, which have been thought to aggravate the polysulfide dissolution and shuttle effects.

Conversion of Mg-Li Bimetallic Alloys to Magnesium Alkoxide and Magnesium Oxide Ceramic Nanowires.

Technologically important composites with enhanced thermal and mechanical properties rely on the reinforcement by the high specific strength ceramic nanofibers or nanowires (NWs) with high aspect ratios. However, conventional synthesis routes to produce such ceramic NWs have prohibitively high cost. Now, direct transformation of bulk Mg-Li alloys into Mg alkoxide NWs is demonstrated without the use of catalysts, templates, expensive or toxic chemicals, or any external stimuli.

Cycle stability of conversion-type iron fluoride lithium battery cathode at elevated temperatures in polymer electrolyte composites.

Metal fluoride conversion cathodes offer a pathway towards developing lower-cost Li-ion batteries. Unfortunately, such cathodes suffer from extremely poor performance at elevated temperatures, which may prevent their use in large-scale energy storage applications. Here we report that replacing commonly used organic electrolytes with solid polymer electrolytes may overcome this hurdle.

Fading Mechanisms and Voltage Hysteresis in FeF -NiF Solid Solution Cathodes for Lithium and Lithium-Ion Batteries.

The rapid development of ultrahigh-capacity alloying or conversion-type anodes in rechargeable lithium (Li)-ion batteries calls for matching cathodes for next-generation energy storage devices. The high volumetric and gravimetric capacities, low cost, and abundance of iron (Fe) make conversion-type iron fluoride (FeF and FeF )-based cathodes extremely promising candidates for high specific energy cells. Here, the substantial boost in the capacity of FeF achieved with the addition of NiF is reported.

Mechanisms of Transformation of Bulk Aluminum-Lithium Alloys to Aluminum Metal-Organic Nanowires.

Fabrication and applications of lightweight, high load-bearing, thermally stable composite materials would benefit greatly from leveraging the high mechanical strength of ceramic nanowires (NWs) over conventional particles or micrometer-scale fibers. However, conventional synthesis routes to produce NWs are rather expensive. Recently we discovered a novel method to directly convert certain bulk bimetallic alloys to metal-organic NWs at ambient temperature and pressure.

Iron Phosphate Coated Flexible Carbon Nanotube Fabric as a Multifunctional Cathode for Na-Ion Batteries.

Conventional slurry casted electrodes cannot stand high loads or be repeatedly flexed or bent without being fractured, which inhibits their use in flexible batteries. Carbon nanotube (CNT) fabric exhibits a paramount mechanical stability and, due to its porosity, can additionally accommodate an active material within its structure. While solution-based protocols cannot achieve conformal coatings of active materials, chemical vapor deposition (CVD) gives a unique opportunity to control and vary the thickness and homogeneity of the coating.

Toward a Long-Chain Perfluoroalkyl Replacement: Water and Oil Repellency of Polyethylene Terephthalate (PET) Films Modified with Perfluoropolyether-Based Polyesters.

Original perfluoropolyethers (PFPE)-based oligomeric polyesters (FOPs) of different macromolecular architecture were synthesized via polycondensation as low surface energy additives to engineering thermoplastics. The oligomers do not contain long-chain perfluoroalkyl segments, which are known to yield environmentally unsafe perfluoroalkyl carboxylic acids. To improve the compatibility of the materials with polyethylene terephthalate (PET) we introduced isophthalate segments into the polyesters and targeted the synthesis of lower molecular weight oligomeric macromolecules.

Transformation of bulk alloys to oxide nanowires.

One dimensional (1D) nanostructures offer prospects for enhancing the electrical, thermal, and mechanical properties of a broad range of functional materials and composites, but their synthesis methods are typically elaborate and expensive. We demonstrate a direct transformation of bulk materials into nanowires under ambient conditions without the use of catalysts or any external stimuli. The nanowires form via minimization of strain energy at the boundary of a chemical reaction front.

A stable lithiated silicon-chalcogen battery via synergetic chemical coupling between silicon and selenium.

Li-ion batteries dominate portable energy storage due to their exceptional power and energy characteristics. Yet, various consumer devices and electric vehicles demand higher specific energy and power with longer cycle life. Here we report a full-cell battery that contains a lithiated Si/graphene anode paired with a selenium disulfide (SeS) cathode with high capacity and long-term stability.

Influence of Binders, Carbons, and Solvents on the Stability of Phosphorus Anodes for Li-ion Batteries.

Phosphorus (P) is an abundant element that exhibits one of the highest gravimetric and volumetric capacities for Li storage, making it a potentially attractive anode material for high capacity Li-ion batteries. However, while phosphorus carbon composite anodes have been previously explored, the influence of the inactive materials on electrode cycle performance is still poorly understood. Here, we report and explain the significant impacts of polymer binder chemistry, carbon conductive additives, and an under-layer between the Al current collector and ball milled P electrodes on cell stability.

Infiltrated Porous Polymer Sheets as Free-Standing Flexible Lithium-Sulfur Battery Electrodes.

Free-standing, high-capacity Li2 S electrodes with capacity loadings in the range from 1.5 to 3.8 mA h cm(-2) are produced by using infiltration of active materials into porous carbonized biomass sheets.

Lithium Titanate Confined in Carbon Nanopores for Asymmetric Supercapacitors.

Porous carbons suffer from low specific capacitance, while intercalation-type active materials suffer from limited rate when used in asymmetric supercapacitors. We demonstrate that nanoconfinement of intercalation-type lithium titanate (Li4Ti5O12) nanoparticles in carbon nanopores yielded nanocomposite materials that offer both high ion storage density and rapid ion transport through open and interconnected pore channels. The use of titanate increased both the gravimetric and volumetric capacity of porous carbons by more than an order of magnitude.

Performance Enhancement and Side Reactions in Rechargeable Nickel-Iron Batteries with Nanostructured Electrodes.

We report for the first time a solution-based synthesis of strongly coupled nanoFe/multiwalled carbon nanotube (MWCNT) and nanoNiO/MWCNT nanocomposite materials for use as anodes and cathodes in rechargeable alkaline Ni-Fe batteries. The produced aqueous batteries demonstrate very high discharge capacities (800 mAh gFe(-1) at 200 mA g(-1) current density), which exceed that of commercial Ni-Fe cells by nearly 1 order of magnitude at comparable current densities. These cells also showed the lack of any "activation", typical in commercial batteries, where low initial capacity slowly increases during the initial 20-50 cycles.

Graphene-Li2S-Carbon Nanocomposite for Lithium-Sulfur Batteries.

Lithium sulfide (Li2S) with a high theoretical specific capacity of 1166mAh g(-1) is a promising cathode material for next-generation Li-S batteries with high specific energy. However, low conductivity of Li2S and polysulfide dissolution during cycling are known to limit the rate performance and cycle life of these batteries. Here, we report on the successful development and application of a nanocomposite cathode comprising graphene covered by Li2S nanoparticles and protected from undesirable interactions with electrolytes.