Much progress has been made in developing high capacity lithium ion battery electrode materials such as silicon anodes. With the powerful nanomaterial design approach, cycle life of silicon anodes ...has been increased significantly. However, nanomaterials have three major issues to be addressed, including severe side reactions due to a large surface area, low tap density and poor scalability. Nanostructured Si secondary clusters (nano-Si SC) are promising for reducing side reactions and increasing tap density, yet the scalability and tap density could still be further improved. Here, we propose a mechanical approach for SC fabrication to address all the problems. With the mechanical approach, >20 g of nano-Si SC per batch was produced even at our university lab scale, with >95% yield. Moreover, much denser packing of nanostructures can be achieved (1.38 g cm super(-3), pellet form), which gives much higher tap density (0.91 g cm super(-3), powder form) and better electrical contact. Accordingly, over 95% of initial capacity is retained after 1400 cycles at 1C, with an average specific capacity of similar to 1250 mA h g super(-1). Stable cycling with >2 mg cm super(-2) of areal mass loading ( similar to 3.5 mA h cm super(-2)) is obtained. After uniformly integrating carbon nanotubes (CNTs) into SCs, intracluster electrical conductivity is further improved. As a result, notably enhanced rate capability is attained, with a high reversible specific capacity of similar to 1140 mA h g super(-1) and similar to 880 mA h g super(-1) at 2C and 4C, respectively.
A group of first-row transition metal dichalcogenides (ME sub(2), M = Fe, Co, Ni; E = S, Se) are introduced as non-precious HER catalysts in an acidic electrolyte. They exhibit excellent catalytic ...activity especially in their nanoparticle form. These compounds expand and enrich the family of high performance HER catalysts.
The discovery of unconventional superconductivity in (La,Ba)
CuO
(ref.
) has motivated the study of compounds with similar crystal and electronic structure, with the aim of finding additional ...superconductors and understanding the origins of copper oxide superconductivity. Isostructural examples include bulk superconducting Sr
RuO
(ref.
) and surface-electron-doped Sr
IrO
, which exhibits spectroscopic signatures consistent with a superconducting gap
, although a zero-resistance state has not yet been observed. This approach has also led to the theoretical investigation of nickelates
, as well as thin-film heterostructures designed to host superconductivity. One such structure is the LaAlO
/LaNiO
superlattice
, which has been recently proposed for the creation of an artificially layered nickelate heterostructure with a singly occupied Formula: see text band. The absence of superconductivity observed in previous related experiments has been attributed, at least in part, to incomplete polarization of the e
orbitals
. Here we report the observation of superconductivity in an infinite-layer nickelate that is isostructural to infinite-layer copper oxides
. Using soft-chemistry topotactic reduction
, NdNiO
and Nd
Sr
NiO
single-crystal thin films are synthesized by reducing the perovskite precursor phase. Whereas NdNiO
exhibits a resistive upturn at low temperature, measurements of the resistivity, critical current density and magnetic-field response of Nd
Sr
NiO
indicate a superconducting transition temperature of about 9 to 15 kelvin. Because this compound is a member of a series of reduced layered nickelate crystal structures
, these results suggest the possibility of a family of nickelate superconductors analogous to copper oxides
and pnictides
.
High ionic conductivity solid polymer electrolyte (SPE) has long been desired for the next generation high energy and safe rechargeable lithium batteries. Among all of the SPEs, composite polymer ...electrolyte (CPE) with ceramic fillers has garnered great interest due to the enhancement of ionic conductivity. However, the high degree of polymer crystallinity, agglomeration of ceramic fillers, and weak polymer–ceramic interaction limit the further improvement of ionic conductivity. Different from the existing methods of blending preformed ceramic particles with polymers, here we introduce an in situ synthesis of ceramic filler particles in polymer electrolyte. Much stronger chemical/mechanical interactions between monodispersed 12 nm diameter SiO2 nanospheres and poly(ethylene oxide) (PEO) chains were produced by in situ hydrolysis, which significantly suppresses the crystallization of PEO and thus facilitates polymer segmental motion for ionic conduction. In addition, an improved degree of LiClO4 dissociation can also be achieved. All of these lead to good ionic conductivity (1.2 × 10–3 S cm–1 at 60 °C, 4.4 × 10–5 S cm–1 at 30 °C). At the same time, largely extended electrochemical stability window up to 5.5 V can be observed. We further demonstrated all-solid-state lithium batteries showing excellent rate capability as well as good cycling performance.
A stretchable Li4Ti5O12 anode and a LiFePO4 cathode with 80% stretchability are prepared using a 3D interconnected porous polydimethylsiloxane sponge based on sugar cubes. 82% and 91% capacity ...retention for anode and cathode are achieved after 500 stretch–release cycles. Slight capacity decay of 6% in the battery using the electrode in stretched state is observed.
For transparent conducting electrodes in optoelectronic devices, electrical sheet resistance and optical transmittance are two of the main criteria. Recently, metal nanowires have been demonstrated ...to be a promising type of transparent conducting electrode because of low sheet resistance and high transmittance. Here we incorporate a mesoscale metal wire (1-5 μm in diameter) into metal nanowire transparent conducting electrodes and demonstrate at least a one order of magnitude reduction in sheet resistance at a given transmittance. We realize experimentally a hybrid of mesoscale and nanoscale metal nanowires with high performance, including a sheet resistance of 0.36 Ω sq(-1) and transmittance of 92%. In addition, the mesoscale metal wires are applied to a wide range of transparent conducting electrodes including conducting polymers and oxides with improvement up to several orders of magnitude. The metal mesowires can be synthesized by electrospinning methods and their general applicability opens up opportunities for many transparent conducting electrode applications.
A 3D graphene cage with a thin layer of electrodeposited nickel phosphosulfide for Li2S impregnation, using ternary nickel phosphosulphide as a highly conductive coating layer for stabilized ...polysulfide chemistry, is accomplished by the combination of theoretical and experimental studies. The 3D interconnected graphene cage structure leads to high capacity, good rate capability and excellent cycling stability in a Li2S cathode.
Heating consumes large amount of energy and is a primary source of greenhouse gas emission. Although energy-efficient buildings are developing quickly based on improving insulation and design, a ...large portion of energy continues to be wasted on heating empty space and nonhuman objects. Here, we demonstrate a system of personal thermal management using metallic nanowire-embedded cloth that can reduce this waste. The metallic nanowires form a conductive network that not only is highly thermal insulating because it reflects human body infrared radiation but also allows Joule heating to complement the passive insulation. The breathability and durability of the original cloth is not sacrificed because of the nanowires’ porous structure. This nanowire cloth can efficiently warm human bodies and save hundreds of watts per person as compared to traditional indoor heaters.
Phase-change memory (PCM) is a promising candidate for data storage in flexible electronics, but its high switching current and power are often drawbacks. In this study, we demonstrate a switching ...current density of ~0.1 mega-ampere per square centimeter in flexible superlattice PCM, a value that is one to two orders of magnitude lower than in conventional PCM on flexible or silicon substrates. This reduced switching current density is enabled by heat confinement in the superlattice material, assisted by current confinement in a pore-type device and the thermally insulating flexible substrate. Our devices also show multilevel operation with low resistance drift. The low switching current and good resistance on/off ratio are retained before, during, and after repeated bending and cycling. These results pave the way to low-power memory for flexible electronics and also provide key insights for PCM optimization on conventional silicon substrates.
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