Ultrafast and Reversible Superwettability Switching of 3D Graphene Foams via Solvent-Exclusive Plasma Treatments.

For highly active electron transfer and ion diffusion, controlling the surface wettability of electrically and thermally conductive 3D graphene foams (3D GFs) is required. Here, we present ultrasimple and rapid superwettability switching of 3D GFs in a reversible and reproducible manner, mediated by solvent-exclusive microwave arcs. As the 3D GFs are prepared with vapors of nonpolar acetone or polar water exclusively, short microwave radiation (≤10 s) leads to plasma hotspot-mediated production of methyl and hydroxyl radicals, respectively.

Activating reversible carbonate reactions in Nasicon solid electrolyte-based Na-air battery via in-situ formed catholyte.

Out of practicality, ambient air rather than oxygen is preferred as a fuel in electrochemical systems, but CO and HO present in air cause severe irreversible reactions, such as the formation of carbonates and hydroxides, which typically degrades performance. Herein, we report on a Na-air battery enabled by a reversible carbonate reaction (NaCO·xHO, x = 0 or 1) in Nasicon solid electrolyte (NaZrSiPO) that delivers a much higher discharge potential of 3.4 V than other metal-air batteries resulting in high energy density and achieves > 86 % energy efficiency at 0.

Wigner-molecularization-enabled dynamic nuclear polarization.

Multielectron semiconductor quantum dots (QDs) provide a novel platform to study the Coulomb interaction-driven, spatially localized electron states of Wigner molecules (WMs). Although Wigner-molecularization has been confirmed by real-space imaging and coherent spectroscopy, the open system dynamics of the strongly correlated states with the environment are not yet well understood. Here, we demonstrate efficient control of spin transfer between an artificial three-electron WM and the nuclear environment in a GaAs double QD.

A New Class of High-Capacity Fe-Based Cation-Disordered Oxide for Li-Ion Batteries: Li-Fe-Ti-Mo Oxide.

Low-cost Fe can be used for forming cation-disordered rocksalt Li-excess (DRX) materials instead of high-cost d -species and then the Fe-based DRX can be promising electrode materials because they can theoretically achieve high capacity, resulting from additional oxygen redox reaction and stable cation-disordered structure. However, Fe-based DRX materials suffer from large voltage hysteresis, low electrochemical activity, and poor cyclability, so it is highly challenging to utilize them as practical electrode materials for a cell. Here, novel high-capacity Li-Fe-Ti-Mo electrode materials (LFTMO) with high average discharge voltage and reasonable stability are reported.

High Initial Coulombic Efficiency of SiO Enabled by Controlling SiO Matrix Crystallization.

SiO is a promising anode material for practical Li-ion batteries because it can achieve a much higher capacity than graphite and a better capacity retention than Si. However, SiO suffers from poor initial Coulombic efficiency (ICE). Here, we report on a fundamentally different approach to increase the low ICE of SiO while achieving high capacity and long-term cycle stability compared to previous approaches such as electrochemical/chemical pre-lithiation processes.

Simultaneously Improved Cubic Phase Stability and Li-Ion Conductivity in Garnet-Type Solid Electrolytes Enabled by Controlling the Al Occupation Sites.

Here, we, for the first time, report on the simultaneous enhancement in cubic phase stability and Li-ion conductivity of garnet-type solid electrolytes (SEs) by adding excess Li/Al. The excess Al/Li creates very large grains of up to 170 μm via the segregation of Al at the grain boundaries and enables preferential Al occupation at 96h sites over 24d sites, a behavior contrary to previous observations. The resulting SE shows improved Li-ion conductivity due to the large grain size and less blocking Li pathway caused by different preferential Al occupation.

Single-Shot Readout of a Driven Hybrid Qubit in a GaAs Double Quantum Dot.

We report a single-shot-based projective readout of a semiconductor hybrid qubit formed by three electrons in a GaAs double quantum dot. Voltage-controlled adiabatic transitions between the qubit operations and readout conditions allow high-fidelity mapping of quantum states. We show that a large ratio both in relaxation time vs tunneling time (≈50) and singlet-triplet splitting vs thermal energy (≈20) allows energy-selective tunneling-based spin-to-charge conversion with a readout visibility of ≈92.

Further Improving Coulombic Efficiency and Discharge Capacity in LiNiO Material by Activating Sluggish ∼3.5 V Discharge Reaction.

The electrochemical activity of LiNiO at the initial cycle and factors affecting its activity were understood. Even though LiNiO can achieve almost theoretical charge capacity, it cannot deliver the theoretical discharge capacity that would result in low 1st Coulombic efficiency (CE). For different upper cut-off voltages at 4.

Fully Exploited Oxygen Redox Reaction by the Inter-Diffused Cations in Co-Free Li-Rich Materials for High Performance Li-Ion Batteries.

To meet the growing demand for global electrical energy storage, high-energy-density electrode materials are required for Li-ion batteries. To overcome the limit of the theoretical energy density in conventional electrode materials based solely on the transition metal redox reaction, the oxygen redox reaction in electrode materials has become an essential component because it can further increase the energy density by providing additional available electrons. However, the increase in the contribution of the oxygen redox reaction in a material is still limited due to the lack of understanding its controlled parameters.

Research Progresses of Garnet-Type Solid Electrolytes for Developing All-Solid-State Li Batteries.

All-Solid-State Batteries (ASSBs) that use oxide-based solid electrolytes (SEs) have been considered as a promising energy-storage platform to meet an increasing demand for Li-ion batteries (LIBs) with improved energy density and superior safety. However, high interfacial resistance between particles in the composite electrode and between electrodes and the use of Li metal in the ASBS hinder their practical utilization. Here, we review recent research progress on oxide-based SEs for the ASSBs with respect to the use of Li metal.

The Presence of the Hairy-Root-Disease-Inducing (Ri) Plasmid in Wheat Endophytic Rhizobia Explains a Pathogen Reservoir Function of Healthy Resistant Plants.

A large number of strains in the species complex (biovar 1 ) have been known as causative pathogens for crown gall and hairy root diseases. Strains within this complex were also found as endophytes in many plant species with no symptoms. The aim of this study was to reveal the endophyte variation of this complex and how these endophytic strains differ from pathogenic strains.

Sublimation-Induced Gas-Reacting Process for High-Energy-Density Ni-Rich Electrode Materials.

Ni-rich layered electrode materials have attracted great attention as a promising cathode candidate for high-energy-density lithium-ion batteries because of their high capacity and relatively low cost. However, they have been suffering from severe capacity fading for cycles, which can originate from several factors such as the phase transition at the end of charge and disintegration of the particles. Herein, a simple and novel sublimation-induced gas-reacting (SIGR) process has been developed by using elemental sulfur to conformally coat Ni-rich layered materials.

Understanding the cation ordering transition in high-voltage spinel LiNiMnO by doping Li instead of Ni.

We determined how Li doping affects the Ni/Mn ordering in high-voltage spinel LiNiMnO(LNMO) by using neutron diffraction, TEM image, electrochemical measurements, and NMR data. The doped Li occupies empty octahedral interstitials (16c site) before the ordering transition, and can move to normal octahedral sites (16d (4b) site) after the transition. This movement strongly affects the Ni/Mn ordering transition because Li at 16c sites blocks the ordering transition pathway and Li at 16d (4b) sites affects electrostatic interactions with transition metals.

Erratum: Fast-Rate Capable Electrode Material with Higher Energy Density than LiFePO : 4.2V LiVPOF Synthesized by Scalable Single-Step Solid-State Reaction.

[This corrects the article DOI: 10.1002/advs.201500366.

Fast-Rate Capable Electrode Material with Higher Energy Density than LiFePO: 4.2V LiVPOF Synthesized by Scalable Single-Step Solid-State Reaction.

Use of compounds that contain fluorine (F) as electrode materials in lithium ion batteries has been considered, but synthesizing single-phase samples of these compounds is a difficult task. Here, it is demonstrated that a simple scalable single-step solid-state process with additional fluorine source can obtain highly pure LiVPOF. The resulting material with submicron particles achieves very high rate capability ≈100 mAh g at 60 C-rate (1-min discharge) and even at 200 C-rate (18 s discharge).

Superior electrochemical performance of N-doped nanocrystalline FeF/C with a single-step solid-state process.

FeF is a promising cathode material for lithium ion batteries but its poor electronic conductivity makes it non-practical. Here, we significantly improve the electrochemical activity of FeF by reducing the strong ionic character of Fe-F with the replacement of some F with N atoms. N-doped nanocrystalline FeF/C achieves the best electrochemical performance among FeF compounds reported to date: ∼95 mA h g at 21.

Sodium Ion Diffusion in Nasicon (NaZrSiPO) Solid Electrolytes: Effects of Excess Sodium.

The Na superionic conductor (aka Nasicon, NaZrSiPO, where 0 ≤ x ≤ 3) is one of the promising solid electrolyte materials used in advanced molten Na-based secondary batteries that typically operate at high temperature (over ∼270 °C). Nasicon provides a 3D diffusion network allowing the transport of the active Na-ion species (i.e.

Understanding abnormal potential behaviors at the 1st charge in Li2S cathode material for rechargeable Li-S batteries.

In this study, electrochemical behaviors of Li2S such as a large potential barrier at the beginning of the 1st charging process and a continuous increase in potential to ∼4 V during the rest of this process were understood through X-ray photoelectron spectroscopy measurements and electrochemical evaluations for a full utilization of Li2S. The large potential barrier to the 1st charge in Li2S can be caused by the presence of insulating oxidized products (Li2SO3 or Li2SO4-like structures) on the surface; simple surface etching can remove them and thereby reduce the potential barrier. Even though the potential barrier was substantially reduced, the electrochemical activity of Li2S might not be improved due to the continuous increase in potential.

Novel and scalable solid-state synthesis of a nanocrystalline FeF3/C composite and its excellent electrochemical performance.

A scalable solid-state reaction is presented to synthesize an FeF3 cathode material by using PTFE as a source of both fluorine and carbon. The method yields nanocrystalline FeF3/C showing excellent electrochemical performance even without any conducting additive. This method can be utilized for engineering MFs' properties and developing other fluorine compounds.

Conformal Coating Strategy Comprising N-doped Carbon and Conventional Graphene for Achieving Ultrahigh Power and Cyclability of LiFePO4.

Surface carbon coating to improve the inherent poor electrical conductivity of lithium iron phosphate (LiFePO4, LFP) has been considered as most efficient strategy. Here, we also report one of the conventional methods for LFP but exhibiting a specific capacity beyond the theoretical value, ultrahigh rate performance, and excellent long-term cyclability: the specific capacity is 171.9 mAh/g (70 μm-thick electrode with ∼10 mg/cm(2) loading mass) at 0.

High-rate performance of a mixed olivine cathode with off-stoichiometric composition.

We highlight that the off-stoichiometric compositional variation is a simply effective method to improve the power density of LiFe0.6Mn0.4PO4.

Thermally driven metastable solid-solution Li(0.5)FePO4 in nanosized particles and its phase separation behaviors.

Nanosized LiFePO4 particles easily show a fast electrochemical response that can be achieved via a non-equilibrium pathway. To understand this intriguing phase transition behavior in nanosized LiFePO4 particles, the metastable solid-solution phase was prepared by thermal treatment with a chemically delithiated nanosized Li0.5FePO4 sample.

Battery materials for ultrafast charging and discharging.

The storage of electrical energy at high charge and discharge rate is an important technology in today's society, and can enable hybrid and plug-in hybrid electric vehicles and provide back-up for wind and solar energy. It is typically believed that in electrochemical systems very high power rates can only be achieved with supercapacitors, which trade high power for low energy density as they only store energy by surface adsorption reactions of charged species on an electrode material. Here we show that batteries which obtain high energy density by storing charge in the bulk of a material can also achieve ultrahigh discharge rates, comparable to those of supercapacitors.