Synergistic Defect Engineering and Interface Stability of Activated Carbon Nanotubes Enabling Ultralong Lifespan All-Solid-State Lithium-Sulfur Batteries.

Due to the high energy density, high safety, and low cost of sulfur, all-solid-state lithium-sulfur batteries (ASSLSBs) are considered one of the most promising next-generation energy storage devices. Nevertheless, the insufficient interfacial contact between solid electrolytes (SEs) and the active material of sulfur leads to inadequate electronic and ionic conduction, which increases interfacial resistance and capacity decay. In this paper, commercial carbon nanotubes (CNTs) are activated to form porous-CNTs (P-CNTs), which are used as sulfur-bearing matrix, forming S@P-CNTs-based composite cathodes for ASSLSBs. Compared with CNTs, P-CNTs possess a larger specific surface area and more oxygen-containing groups, providing enhanced interfacial contact and stability between S@P-CNTs and Li6PS5Cl SE, which are confirmed by scanning electron microscopy, X-ray photoelectron spectroscopy, and density functional theory calculations. Moreover, P-CNTs can form a 3D conductive network in the composite cathodes, facilitating the migration of electrons and the diffusion of ions, as well as improving the utilization of sulfur. As a result, the S@P-CNTs-based ASSLSBs display excellent electrochemical performances, especially rarely reported ultralong lifespan, which deliver a capacity of 1099.2 mA h g-1 at a current density of 1.34 mA cm-2, and remarkably maintain 70.4% of the initial capacity over 1400 cycles.

Multichalcogen-Integrated Cathodes for Novel Lithium-Chalcogenide Batteries in Ether and Ester Electrolytes.

Lithium-sulfur (Li-S) batteries and lithium-selenium (Li-Se) batteries that contain only one single active element have unique advantages and disadvantages. Inspired by ternary lithium batteries, multielement chalcogenide compounds with integrated advantages may improve upon the performance of lithium-chalcogenide batteries at the source. In this work, activated carbon (AC) with an Al2O3@SiO2 heterojunction is used as the carrier, and the performances and mechanisms of elemental substances (X/AC, X = S, Se, and Te) are studied in ether and ester electrolytes as the basis for preparing multielement chalcogenide composites (SST/AC, SST: S-Se-Te compound). In the ester electrolyte system, SST811/AC (where S/Se/Te = 8:1:1, molar ratio) exhibited the best cycling performance, and the capacity remained at 1024.9 mA h g-1 after 300 cycles. The characterization results revealed the mechanisms and sequences of the gradual liquid-phase reactions of SST/AC in ether electrolytes and the direct solid-phase reactions in ester electrolytes. The active elements in SST/AC fully demonstrated their own functions, enabling the effective construction of new lithium-chalcogenide battery systems. This work provides inspiration for the subsequent research of multielement lithium-chalcogenide batteries and paves the way for their application.

Dilute Electrolyte to Mitigate Capacity Decay and Voltage Fading of Co-Free Li-Rich Cathode for Next-Generation Li-Ion Batteries.

Li-rich cathodes have potential for use in next-generation Li-ion batteries (LIBs) owing to their high specific capacity and low cost. However, their intrinsic cycling decay and voltage fading limit practical applications. In addition, these cathodes contain Co, which is nonrenewable, scarce, and expensive. This situation severely limits the rapid and sustainable development of low-cost LIBs. This paper introduces a novel dilute electrolyte to overcome these limitations based on the Co-free Li-rich Li1.2Mn0.54Ni0.26O2 (LMNO) cathode. An even and robust cathode-electrolyte interface (CEI) formed on the surface of LMNO further protects it from side reactions in the dilute electrolyte. This Co-free Li-rich cathode exhibits the best electrochemical performance reported to date among Li-rich cathodes in terms of outstanding cycling stability (capacity retention of 99.8% at 0.5 C) and dramatically suppressed voltage fading (only 0.3% after 100 cycles). This study demonstrates the potential of Co-free Li-rich cathodes for applications in next-generation LIBs.

The effect of cooling process on the structure and charge/discharge capacities of Li-rich solid-solution layered oxide cathode materials for the Li-ion battery.

The effect of cooling process after calcination at 900 °C in the preparation of cathode materials, on the crystal structure and charging/discharging capacities of Li2MnO3-LiNi1/2Mn1/2O2-LiNi1/3Mn1/3Co1/3O2 Li-rich solid-solution layered oxide (LLO) cathode materials for the lithium ion battery was examined in twenty-one LLO samples having different compositions. This was achieved by applying two types of cooling processes: (i) quenching the calcinated LLO samples with liquid nitrogen (quenched cooling), and (ii) slow cooling of LLO samples in the furnace at a controlled decreasing rate of the temperature (slow cooling). The results of the comparison between discharging capacities observed with LLO samples prepared with two types of cooling processes indicated that the cooling process for LLO samples to exhibit high discharge capacity was not limited to either one. The process that can be more effective for LLO samples to exhibit the high discharge capacity depended on the composition of LLO samples. LLO samples containing Li2MnO3 of over 60% exhibited higher discharge capacity when samples were quenched with liquid nitrogen than those prepared with the slow cooling process. Among LLOs examined, the effect of quenching was maximum when the Li2MnO3 content was 60%. As the LLO composition deviated from the line of 60% Li2MnO3 in the Li[Li0.20Mn0.58Ni0.18Co0.04]O2 sample compositions, the effect of quenching became smaller and the slow cooling process was superior to the quenching process. A connection was thus made between the structural difference of LLO samples prepared with the two types of cooling processes and the cathode performance was observed.

Surface coating of a LiNi x Co y Al1-x-y O2 (x > 0.85) cathode with Li3PO4 for applying a water-based hybrid polymer binder during Li-ion battery preparation.

To produce water-stable Ni-rich lithium nickel cobalt aluminum oxides (LiNi x Co y Al1-x-y O2, x > 0.85, NCAs), the formation of trilithium phosphate (Li3PO4)-coated layers on the NCA surfaces was attempted through the use of a surface reaction in a mixture of ethanol and water and a post-heat treatment at 350 and 400 °C. Based on the results of X-ray photoelectron spectroscopy (XPS), the coated layers consisted of nickel phosphate (Ni3(PO4)2) and Li3PO4. The coated NCA surface could have sufficient water stability to maintain the cathode performance in a water slurry for 1 day. In addition, the coated layers formed on the NCA surfaces did not block Li+-ion transfer through the Ni3(PO4)2/Li3PO4-coating layers and enhanced the high-rate discharge performance.

Designing conductive networks of hybrid carbon enables stable and long-lifespan cotton-fiber-based lithium-sulfur batteries.

In modern society, flexible rechargeable batteries have become a burgeoning apodictic choice for wearable devices. Conventional lithium-sulfur batteries lack sufficient flexibility because their electrode materials are too rigid to bend. Along with the inherent high theoretical capacity of sulfur, lithium-sulfur batteries have some issues, such as dissolution and shuttle effect of polysulfides, which restricts their efficiency and practicability. Here, a flexible and "dead-weight"-free lithium-sulfur battery substrate with a three-dimensional structure was prepared by a simple strategy. With the cooperative assistance of carbon nanotubes and graphene attached to cotton fibers, the lithium-sulfur battery with 2.0 mg cm-2 sulfur provided a high initial discharge capacity of 1098.7 mA h g-1 at 1C, and the decay rate after 300 cycles was only 0.046% per cycle. The initial discharge capacity at 2C was 872.4 mA h g-1 and the capacity was maintained 734.4 mA h g-1 after 200 cycles with only a 0.079% per cycle decay rate.

Surface double coating of a LiNi a Co b Al1-a-b O2 (a > 0.85) cathode with TiO x and Li2CO3 to apply a water-based hybrid polymer binder to Li-ion batteries.

Recently a water-based polymer binder has been getting much attention because it simplifies the production process of lithium ion batteries (LIBs) and reduce their cost. The surface of LiNi a Co b Al1-a-b O2 (a > 0.85, NCA) cathode with a high voltage and high capacity was coated doubly with water-insoluble titanium oxide (TiO x ) and Li2CO3 layers to protect the NCA surface from the damage caused by contacting with water during its production process. The TiO x layer was at first coated on the NCA particle surface with a tumbling fluidized-bed granulating/coating machine for producing TiO x -coated NCA. However, the TiO x layer could not coat the NCA surface completely. In the next place, the coating of the TiO x -uncoated NCA surface with Li2CO3 layer was conducted by bubbling CO2 gas in the TiO x -coated NCA aqueous slurry on the grounds that Li2CO3 is formed through the reaction between CO3 2- ions and residual LiOH on the TiO x -uncoated NCA surface, resulting in the doubly coated NCA particles (TiO x /Li2CO3-coated NCA particles). The Li2CO3 coating is considered to take place on the TiO x layer as well as the TiO x -uncoated NCA surface. The results demonstrate that the double coating of the NCA surface with TiO x and Li2CO3 allows for a high water-resistance of the NCA surface and consequently the TiO x /Li2CO3-coated NCA particle cathode prepared with a water-based binder possesses the same charge/discharge performance as that obtained with a "water-uncontacted" NCA particle cathode prepared using the conventional organic solvent-based polyvinylidene difluoride binder.

Structural Characterization of 2D Zirconomolybdate by Atomic Scale HAADF-STEM and XANES and Its Highly Stable Electrochemical Properties as a Li Battery Cathode.

The structural determination of nanomaterials and their application in energy storage and transfer are of great importance. Herein, a layered zirconomolybdate with a two-dimensional structure was synthesized. Atomic resolution electron microscopy was utilized for direct visualization of the structure that was further confirmed by powder X-ray diffraction and X-ray absorption near-edge structure analyses. The structure of the molecular sheet was stable at a high temperature in an oxidative atmosphere. The electrochemical performance of the material was evaluated with a Li battery composed of the calcined material as a cathode. Li ions were reversibly inserted and extracted between the layers without collapse of the structure of the material. The electrochemical properties of the material were derived from the reversible redox activity of the Mo ions and Zr ions in the material as well as the flexibility of the molecular layer of the material.

High-Performance Cathode Based on Microporous Mo-V-Bi Oxide for Li Battery and Investigation by Operando X-ray Absorption Fine Structure.

The development of cathode-active material of Li battery is important for the current emerging energy transferring and saving problems. A stable crystalline microporous complex metal oxide based on Mo, V, and Bi is an active and suitable material for Li battery. High capacity (380 Ah/kg) and stable cycle performance are achieved. X-ray absorption near-edge structure analyses demonstrate that the original Mo6+ and V4+ ions are reduced to Mo4+ and V3+ in the discharging process, respectively, which results in a 70-electron reduction per formula. The reduced metal ions can be reoxidized reversibly in the next charging process. Furthermore, extended X-ray absorption fine structure analyses reveal that the Mo-O bonds in the material are lengthened in the discharging process probably due to interaction with Li+ without change of the basic structure.

Correlation between the surface electronic structure and CO-oxidation activity of Pt alloys.

The surface electronic structure and CO-oxidation activity of Pt and Pt alloys, Pt3T (T = Ti, Hf, Ta, Pt), were investigated. At temperatures below 538 K, the CO-oxidation activities of Pt and Pt3T increased in the order Pt < Pt3Ti < Pt3hHf < Pt3Ta. The center-of-gravity of the Pt d-band (the d-band center) of Pt and Pt3T was theoretically calculated to follow the trend Pt3Ti < Pt3Ta < Pt3Hf < Pt. The CO-oxidation activity showed a volcano-type dependence on the d-band center, where Pt3Ta exhibited a maximum in activity. Theoretical calculations demonstrated that the adsorption energy of CO on the catalyst surface monotonically decreases with the lowering of the d-band center because of diminished hybridization of the surface d-band and the lowest-unoccupied molecular orbital (LUMO) of CO. The observed volcano-type correlation between the d-band center and the CO oxidation activity is rationalized in terms of the CO adsorption energy, which counterbalances the surface coverage by CO and the rate of CO oxidation.

Interleaved mesoporous copper for the anode catalysis in direct ammonium borane fuel cells.

Mesoporous materials with tailored microstructures are of increasing importance in practical applications particularly for energy generation and/or storage. Here we report a mesoporous copper material (MS-Cu) can be prepared in a hierarchical microstructure and exhibit high catalytic performance for the half-cell reaction of direct ammonium borane (NH3BH3) fuel cells (DABFs). Hierarchical copper oxide (CuO) nanoplates (CuO Npls) were first synthesized in a hydrothermal condition. CuO Npls were then reduced at room temperature using water solution of sodium borohydride (NaBH4) to yield the desired mesoporous copper material, MS-Cu, consisting of interleaved nanoplates with a high density of mesopores. The surface of MS-Cu comprised high-index facets, whereas a macroporous copper material (MC-Cu), which was prepared from CuO Npls at elevated temperatures in a hydrogen stream, was surrounded by low-index facets with a low density of active sites. MS-Cu exhibited a lower onset potential and improved durability for the electro-oxidation of NH3BH3 than MC-Cu or copper particles because of the catalytically active mesopores on the interleaved nanoplates.

Synthesis and electrocatalytic performance of atomically ordered nickel carbide (Ni3C) nanoparticles.

Atomically ordered nickel carbide, Ni3C, was synthesized by reduction of nickel cyclopentadienyl (NiCp2) with sodium naphthalide to form Ni clusters coordinated by Cp (Ni-Cp clusters). Ni-Cp clusters were thermally decomposed to Ni3C nanoparticles smaller than 10 nm. The Ni3C nanoparticles showed better performance than Ni nanoparticles and Au nanoparticles in the electrooxidation of sodium borohydride.

One-pot synthesis of platinum-based nanoparticles incorporated into mesoporous niobium oxide-carbon composites for fuel cell electrodes.

Catalyst-electrode design is crucial for the commercialization and widespread use of polymer electrolyte membrane fuel cells. There are considerable challenges in making less expensive, more durable, and more active catalysts. Herein, we report the one-pot synthesis of Pt and Pt-Pb nanoparticles incorporated into the pores of mesoporous niobium oxide-carbon composites. The self-assembly of block copolymers with niobium oxide and metal precursors results in an ordered mesostructured hybrid. Appropriate heat treatment of this hybrid produces highly crystalline, well-ordered mesoporous niobium oxide-carbon composites with Pt (or Pt-Pb) nanoparticles incorporated into the mesopores. The in situ-generated graphitic-like carbon material prevents the collapse of the mesostructure, while the metal oxide crystallizes at high temperatures and enhances the electrical conductivity of the final material. Formic acid electrooxidation with this novel material shows 4 times higher mass activities (3.3 mA/microg) and somewhat lower onset potentials (-0.24 V vs Ag/AgCl) than the best previously reported values employing Pt-Pb intermetallic nanoparticles supported on conducting carbon (0.85 mA/microg and -0.18 V, respectively).

Urban warming trends in several large Asian cities over the last 100 years.

In this paper, the long-term trends in surface temperature in several large Asian cities (Seoul, Tokyo, Osaka, Taipei, Manila, Bangkok, and Jakarta) have been analyzed for estimating the effects of urban warming. A new index, E-HII, is proposed: it is the value obtained by subtracting the temperature data of the four grids around the city from the observational temperature data in the city. Osaka shows the largest E-HII, increasing from approximately 2.4 degrees C in 1901 to almost 3 degrees C after 1981. The E-HIIs of Seoul, Tokyo, and Taipei, have increased by 1 degrees C to 2 degrees C. Jakarta and Bangkok exhibited a lower E-HII. E-HIIs of Manila and Bangkok have been increasing rapidly after 1961.

Electrocatalytic performance of fuel oxidation by Pt3Ti nanoparticles.

A Pt-based electrocatalyst for direct fuel cells, Pt3Ti, has been prepared in the form of nanoparticles. Pt(1,5-cyclooctadiene)Cl2 and Ti(tetrahydrofuran)2Cl4 are reduced by sodium naphthalide in tetrahydrofuran to form atomically disordered Pt3Ti nanoparticles (FCC-type structure: Fm3m; a = 0.39 nm; particle size = 3 +/- 0.4 nm). These atomically disordered Pt3Ti nanoparticles are transformed to larger atomically ordered Pt3Ti nanoparticles (Cu3Au-type structure: Pm3m; a = 0.3898 nm; particle size = 37 +/- 23 nm) by annealing above 400 degrees C. Both atomically disordered and ordered Pt3Ti nanoparticles show lower onset potentials for the oxidation of formic acid and methanol than either pure Pt or Pt-Ru nanoparticles. Both atomically disordered and ordered Pt3Ti nanoparticles show a much lower affinity for CO adsorption than either pure Pt or Pt-Ru nanoparticles. Atomically ordered Pt3Ti nanoparticles show higher oxidation current densities for both formic acid and methanol than pure Pt, Pt-Ru, or atomically disordered Pt3Ti nanoparticles. Pt3Ti nanoparticles, in particular the atomically ordered materials, have promise as anode catalysts for direct fuel cells.

Synthesis, characterization, and electrocatalytic activity of PtPb nanoparticles prepared by two synthetic approaches.

Intermetallic PtPb nanoparticles have been synthesized by two solution-phase reduction methods. In the first (PtPb-B), Pt and Pb salts were reduced by sodium borohydride in methanol at room temperature. In the second (PtPb-N), metal-organic Pt and Pb precursors were reduced by sodium naphthalide in diglyme at 135 degrees C. Both methods produced small agglomerated nanoparticles of the ordered intermetallic PtPb (mean crystal domain size <15 nm) which were characterized by pXRD, SEM, UHV-STEM, BET, EDX, and electron diffraction. The electrocatalytic activity of PtPb nanoparticles produced by both methods toward formic acid and methanol oxidation was investigated and compared to Pt and PtRu. Both PtPb-B and PtPb-N nanoparticles exhibited enhanced electrocatalytic activity compared to commercially available Pt black and PtRu nanoparticles. For formic acid oxidation, the PtPb nanoparticles exhibited considerably lower onset potentials and higher current densities than Pt or PtRu. For methanol oxidation, the PtPb nanoparticles had onset potentials slightly positive of PtRu but exhibited higher current densities at potentials about 100 mV positive of onset. The general applicability of these methods for the synthesis of nanoparticles of ordered intermetallic phases is discussed.