Thin Interfacial Layer Research Articles

Tuning Electrolyte Solvation Structure and CEI Film to Enable Long Lasting FSI−‐Based Dual‐Ion Battery

AbstractDual‐ion battery (DIB) is a promising energy storage system because it can provide high power. However, the stability and rate performance of the battery depend strongly on the type of salt and solvents in the electrolyte. Herein, the use of lithium bis(fluorosulfonyl)imide (LiFSI) is studied, which has better high‐temperature stability, as salt in the DIB and develop a 3 m LiFSI fluoroethylene carbonate/methyl 2,2,2‐trifluoroethyl carbonate (FEC/FEMC) = 3:7 electrolyte, which stabilizes graphite–lithium DIB with 94.1% capacity retention after 2000 cycles at 5C. The DIB also exhibits excellent rate performance with 100.4 mAh g−1 capacity at 30C, with a utilization of 96.3% compared to capacity at 2C. The outstanding electrochemical performance is attributed to the thin cathode electrolyte interface (CEI) layer and fast FSI− transport kinetics, confirmed by X‐ray photoelectron spectroscopy and activation energy calculation. Superior cycle and rate performances are also obtained from a graphite–graphite full cell. Though, increasing salt concentration to 5 and 6 m leads to sluggish FSI− de‐intercalation reaction and lower capacity, which is attributed to solvent co‐intercalation. The research suggests that the electrolyte plays an important role in ion transport, surface film formation, and stability of DIB.

Evidence of Improved Thermal Stability via Nanoscale Contact Engineering in IGZO Source-Gated Thin-Film Transistors

Despite rapidly expanding interest in thin-film source-gated transistors (SGTs), the high-temperature dependence of drain current (TDDC) in devices comprising Schottky source barriers is delaying wide adoption. To reduce this effect, alternative source designs have been theorized. Specifically, introducing additional nanoscale layers at the source contact should facilitate the tunneling of charge carriers at the Fermi energy level with negligible TDDC. Here, we fabricate amorphous In <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{2}}$</tex-math> </inline-formula> Ga <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{2}}$</tex-math> </inline-formula> ZnO <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{7}}$</tex-math> </inline-formula> tunnel-contact SGTs (TC-SGTs) with three times lower TDDC than polysilicon transistors with Schottky contacts. Numerical simulations help elucidate the control mechanisms. We show that the potential profile across the semiconductor in the bulk of the source-gate overlap region determines injection current, and the introduction of a thin interfacial layer at the contact reduces the role of the contact metal work function (WF) in current control and associated temperature effects. This device architecture adds improved thermal stability to the long list of SGT benefits, including low voltage saturation, power-efficient operation, high intrinsic gain, device-to-device uniformity, and robustness to mechanical and electrical stress.

High sulfur-doped microporous carbon for high-rate potassium ion storage: Interspace design and solvent effect

Carbon materials as promising anode for potassium ion batteries (PIBs) suffer from low rate performance, which is attributed to sluggish K+ transport stemming from limited carbon interspace and elusive solvent effect. Herein, interspace design and solvent effect are investigated to resolve this issue. Through an innovative salt template assisted molten sulfur method, large hollow pores, massive micropores and expanded interlayer spacing are integrated in a high sulfur-doped porous carbon (S-PC), showing obviously higher rate capability (351.5 and 122.3 mA h g−1 at 0.1 and 20 A g−1, respectively) than pristine porous carbon (PC). Furthermore, the S-PC exhibits significantly-higher rate performance in ester-based electrolyte (1 M KFSI/EC + DEC) than in ether one (1 M KFSI/DME). Kinetic study demonstrates advantage of interspace design and ester-based electrolyte on promoting faster K+ transport. The explicit solvent effect on S-PC is further examined by XPS and HRTEM analyses, revealing a desirable inorganic KF-salt-dominated, thin solid electrolyte interface (SEI) layer in ester-based electrolyte. This work opens new avenues for precise design of advanced carbon materials for high-rate PIBs.

Interface-Engineered Organic Near-Infrared Photodetector for Imaging Applications.

We report a high-speed low dark current near-infrared (NIR) organic photodetector (OPD) on a silicon substrate with amorphous indium gallium zinc oxide (a-IGZO) as the electron transport layer (ETL). In-depth understanding of the origin of dark current is obtained using an elaborate set of characterization techniques, including temperature-dependent current-voltage measurements, current-based deep-level transient spectroscopy (Q-DLTS), and transient photovoltage decay measurements. These characterization results are complemented by energy band structures deduced from ultraviolet photoelectron spectroscopy. The presence of trap states and a strong dependency of activation energy on the applied reverse bias voltage point to a dark current mechanism based on trap-assisted field-enhanced thermal emission (Poole-Frenkel emission). We significantly reduce this emission by introducing a thin interfacial layer between the donor: acceptor blend and the a-IGZO ETL and obtain a dark current as low as 125 pA/cm2 at an applied reverse bias of -1 V. Thanks to the use of high-mobility metal-oxide transport layers, a fast photo response time of 639 ns (rise) and 1497 ns (fall) is achieved, which, to the best of our knowledge, is among the fastest reported for NIR OPDs. Finally, we present an imager integrating the NIR OPD on a complementary metal oxide semiconductor read-out circuit, demonstrating the significance of the improved dark current characteristics in capturing high-quality sample images with this technology.

RETRACTED: Interfacial passivation by Mono-ethanolamine in planar perovskite solar-cell

Aluminium doped zinc oxide (AZO) is a potential replacement for the conventionally used TiO2 as an electron transport layer (ETL) in low-temperature solution processes for hybrid perovskite solar cells (PvSCs). However, the defects and energy-band mismatch at the ETL/perovskite interface accelerate the interfacial carrier's recombination, leading to a decrease in the fill factor (FF) and current density (JSC). To address this issue, a thin interfacial modification layer of monoethanolamine (MEA) has been used which not only reduces the energy barrier between AZO/perovskite for accelerating the charge transfer but also passivates the trap states on the perovskite interface. Due to the synergistic effect of charge extraction promotion and trap density passivation , the champion PvSCs exhibit a higher value of PCE of 8.25 % with a current density (JSC) of 22.59 mA/cm2 and FF of 46.55% compared to the without MEA passivate PvSCs and the device maintains 70% of its topmost PCE after 1000 h under ambient atmosphere, without any encapsulation. This interface engineering based on MEA provides a feasible and excellent strategy to fabricate the PvSCs with improved efficiency and stability of planar device architecture.

Polyoxometalate–polymer hybrid artificial layers for ultrastable and reversible Zn metal anodes

Zn is considered a promising anode candidate for aqueous metal batteries owing to its high theoretical capacity, proper deposition potential within the electrochemical stability window of aqueous electrolytes, and low cost. However, dendrite formation, passivation layers, and hydrogen evolution reactions limit the reversibility and stability of Zn metal anodes. Herein, we demonstrate an organic–inorganic hybrid layer composed of polyoxometalate (POM) and poly(ethylene glycol) dimethyl ether (PEGDME) on the Zn metal surface. The POM–PEGDME hybrid layer, composed of POM known as an ‘electron sponge’ and PEGDME with high ionic conductivity, was obtained through a facile slurry coating method. While POM provided an energetically favorable zincophilic surface, PEGDME assisted in the formation of a thin (10–15 nm) and uniform artificial interface layer and diversified the oxidation number of molybdenum in POM. The POM-PEGDME-coated Zn metal anode achieved a high cumulative capacity of 9,050 h at 10 mA cm−2, delivering approximately 1.7 times higher capacity retention than that of bare Zn foil in a battery cell paired with a β-MnO2 cathode. This study provides significant implications for designing synergized organic–inorganic hybrid artificial layers for metal anode protection.

In situ electrochemical modification of the Li/Li1.3Al0.3Ti1.7(PO4)3 interface in solid lithium metal batteries via an electrolyte additive

Solid-state Li batteries employing Li-metal anodes and solid Li/Li1.3Al0.3Ti1.7(PO4)3 (LATP) electrolytes have emerged as promising next-generation energy storage devices due to their high energy density and safety. However, their performance is seriously limited by the irreversible reactivity of LATP with the Li-metal anode and the poor solid–solid interfacial contact between them, which result in relatively low ionic conductivity at the interface. The present work addresses these issues by presenting a method for modifying the Li/LATP interface in situ by applying 2-(trimethylsilyl) phenyl trifluoromethanesulfonate (2-(TMS)PTM) as a new type of electrolyte additive between the Li anode and the LATP electrolyte when assembling the battery, and then forming a uniform and thin interfacial layer via redox reactions occurring during the application of multiple charge–discharge cycles to the resulting battery. As a result of the significantly improved chemical compatibility between the Li anode and the LATP electrolyte, an as-assembled battery delivers a high reversible capacity of 165.7 mAh g−1 and an outstanding capacity retention of 86.2% after 300 charge–discharge cycles conducted at a rate of 0.2C and a temperature of 30 °C. Accordingly, this work provides a new strategy for developing advanced solid-state Li metal batteries by tailoring the interface between the Li anode and the solid electrolyte.

Preliminary investigation of Cr-coated F82H: Evolution of microstructure and mechanical properties at the F82H/Cr interface during solid-state diffusion bonding above Ac1 temperature

Solid-state diffusion bonding was employed to join F82H steel and pure Cr metal under high vacuum at various temperatures above Ac1 in the range 1114 to 1323 K for 60 min, and at 1323 K for 120 min. After successful bonding at all temperatures, the F82H/Cr interface and interdiffusion zone were characterised using SEM-EDS, TEM and EBSD analysis, with respect to diffusion behaviour, chemical composition and microstructure. A thin interface layer formed on the Cr side of the joint, which decreased in thickness with decreasing bonding temperature, and was rich in M23C6 with mixed columnar and particulate nature. The depth of Cr diffusion into F82H decreased with decreasing bonding temperature. At temperatures ≥1231 K a layer of ferrite grains formed in the F82H region adjacent to the interface, due to the combined stabilising effect of enhanced Cr concentration and depleted C. At the lowest bonding temperature of 1114 K, a lath martensite microstructure was retained throughout the F82H due to a significantly lower extent of Cr and C diffusion. The diffusion coefficient of Cr in F82H was determined at all temperatures examined, and the activation energy of Cr diffusion in F82H >Ac1 was approximated as 225 KJ mol−1. Finally, hardness testing of the interface and interdiffusion zone suggests the F82H properties were retained after bonding at the lowest temperature of 1114 K, however at higher temperatures the newly formed ferrite region was softer. Further research is required to understand the impact of the hard M23C6-rich interface layer on mechanical properties of the joint, and whether microstructural change can be minimised, or even eliminated, below the Ac1 temperature.

Coverage-Dependent Modulation of Charge Density at the Interface between Ag(001) and Ruthenium Phthalocyanine

When an organic film is deposited on a metal surface, charge layers are formed at the interface. These are an important feature of the interface electronic structure and play a crucial role as separation layers between electrodes and active layers in organic devices. Here, we report on a study of the interface between diruthenium phthalocyanine, (RuPc)2, and the Ag(001) surface. The molecules form two different commensurable arrangements on the substrate, a low density one for a coverage well below the first monolayer and a high density one up to the completion of the monolayer. The focus of this study is on the interface states evolution with the molecular density on the metal surface and the charge distribution in the thin interfacial layer between molecules and substrate. From this investigation, conducted by low energy electron diffraction, scanning tunneling microscopy/spectroscopy, photoemission spectroscopy, and density functional theory, we have found that, even if individual molecules are characterized by a quite similar surface-to-molecule charge transfer pattern, the two molecular arrangements present different valence band structures and, more interestingly, different modulations of the interface charge. These charge modulations are governed by interfacial states energetically resonant with the molecular states, localized at the position of the molecules as well as by a reaction of the electronic cloud of the metal surface to the molecular adsorption due to a Pauli pushback effect. This complex, spatial charge modulation makes the (RuPc)2/Ag(001) an interesting case of interaction intermediate between physisorption and chemisorption.

A Modified Thin-Layer Interface Model for Wave Propagation Across a Rock Fracture with Viscoelastic Filling

A modified thin-layer interface model (MTLIM) is established to investigate stress wave propagation across a fracture filled with viscoelastic materials in a rock mass. First, this MTLIM treats the viscoelastic filling material as a composite of elastic thin layers and viscoelastic bonds. The displacement discontinuity at the bond is described by the Zener model, and the wave propagation equation through the fracture is derived in the time domain. Then, this MTLIM is degenerated to the thin-layer interface model (TLIM) for the extreme case and verified by the transmitted wave in a dynamic experiment. Its performance is compared with those of the TLIM and a zero-thickness interface model (ZTIM). Finally, the waveform evolution, transmission and reflection coefficients, and the energy dissipation ratio for stress wave incidence are investigated for viscoelastic filled fractures at different thicknesses. Results indicate that the MTLIM has better performance than the TLIM, Maxwell model, and Kelvin model in accurately reproducing the dynamic response of stress waves through viscoelastic filled fractures. Significant differences are observed between thin and thick filled fractures in the variation of the waveform and the velocity transmission and reflection coefficients with filling thickness. A thin filled fracture can cause more total energy dissipation than a thick one in some cases. The MTLIM can describe the effects of repeated reflections and the viscoelastic effects of filled fractures on the frequency and amplitude of seismic responses.

Strain in Copper/Ceria Heterostructure Promotes Electrosynthesis of Multicarbon Products

Elastic strains in metallic catalysts induce enhanced selectivity for carbon dioxide reduction (CO2R) toward valuable multicarbon (C2+) products. However, under working conditions, the structure of catalysts inevitably undergoes reconstruction, hardly retaining the initial strain. Herein, we present a metal/metal oxide synthetic strategy to introduce and maintain the tensile strain in a copper/ceria heterostructure, enabled by the presence of a thin interface layer of Cu2O/CeO2. The tensile strain in the copper domain and deficient electron environment around interfacial Cu sites resulted in strengthened adsorption of carbonaceous intermediates and promoted *CO dimerization. The strain effect in the copper/ceria heterostructure leads to an improved C2+ selectivity with a maximum Faradaic efficiency of 76.4% and a half-cell power conversion efficiency of 49.1%. The fundamental insights gained from this system can facilitate the rational design of heterostructure catalysts for CO2R.

Interface Engineering Enabled Low Temperature Growth of Magnetic Insulator on Topological Insulator

AbstractCombining topological insulators (TIs) and magnetic materials in heterostructures is crucial for advancing spin‐based electronics. Magnetic insulators (MIs) can be deposited on TIs using the spin‐spray process, which is a unique nonvacuum, low‐temperature growth process. TIs have highly reactive surfaces that oxidize upon exposure to atmosphere, making it challenging to grow spin‐spray ferrites on TIs. In this work, it is demonstrated that a thin titanium capping layer on TI, followed by oxidation in atmosphere to produce a thin TiOx interfacial layer, protects the TI surface, without significantly compromising spin transport from the magnetic material across the TiOx to the TI surface states. First, it is demonstrated that in Bi2Te3/TiOx/Ni80Fe20 heterostructures, TiOx provides an excellent barrier against diffusion of magnetic species, yet maintains a large spin‐pumping effect. Second, the TiOx is also used as a protective capping layer on Bi2Te3, followed by the spin‐spray growth of the MI, NixZnyFe2O4 (NZFO). For the thinnest TiOx barriers, Bi2Te3/TiOx/NZFO samples have antiferromagnetic (AFM) disordered interfacial layer because of diffusion. With increasing TiOx barrier thickness, the diffusion is reduced, but still maintains strong interfacial magnetic exchange‐interaction. These experimental results demonstrate a novel method of low‐temperature growth of magnetic insulators on TIs enabled by interface engineering.

Optimizing the size and amount of CdS quantum dots for efficiency enhancement in CdS/N719 co-sensitized solar cells

Co-sensitization of TiO 2 photoanodes in solar cells with Ruthenium dye and quantum dots offer better photovoltaic performance compared to the sensitization by the dye only. In the present study, TiO 2 nanostructured photoanode was co-sensitized with CdS quantum dots and N719 dye. CdS quantum dots were deposited using successive ionic layer adsorption and reaction (SILAR). A suitable thin ZnS interfacial layer has been introduced between two sensitizers to prevent the corrosion of CdS quantum dots by the iodide-based liquid electrolyte. In order to get the highest efficiency, the number of SILAR cycles for CdS quantum dot deposition has been optimized. A power conversion efficiency of 6.79% with short-circuit current density of 15.55 mA cm −2 and open circuit voltage of 764.5 mV have been obtained for the co-sensitized solar cell made with TiO 2 /CdS/ZnS/N719 co-sensitized photoanode under the illumination of 100 mW cm −2 with AM 1.5 spectral filter. Efficiency and short-circuit current density of the solar cell have been enhanced by 11.31% and 6.58% respectively due to the co-sensitization. The optimized co-sensitized solar cell shows a higher incident photon to current conversion efficiency and a reduced electron recombination compared to the solar cell with dye-sensitized photoanode. Higher recombination resistance and longer electron lifetime of the solar cell with CdS/ZnS/N719 co-sensitized TiO 2 photoanode have contributed to the increased short circuit current and open circuit voltage leading to the enhanced efficiency of 6.79% which is among the highest for a co-sensitized dye sensitized solar cell . • TiO 2 photoanode was co-sensitized with CdS quantum dots and N719 dye. • ZnS layer was introduced between CdS and N719 to prevent the corrosion of CdS. • Number of CdS SILAR cycles was optimized to get the highest solar cell efficiency. • Solar cell efficiency of 6.79% was obtained for TiO 2 /CdS/ZnS/N719 photoanode. • New photoanode showed a high recombination resistance and long electron lifetime. • 6.79% is among the highest efficiencies reported for co-sensitized solar cells.

Electrical properties and microstructure of V/Al/Ni/Au contacts on n-Al0.65Ga0.35N:Si with different Au thicknesses and annealing temperatures

We investigated the formation of ohmic contacts as a result of intermetallic phase formation between V, Al, Ni, and Au in V/Al/Ni/Au metal stacks on n-Al0.65Ga0.35N:Si. In particular, the influence of Au metal thickness and annealing temperature was analysed. The lowest annealing temperature of 750 °C for an ohmic contact with a smooth surface and a contact resistivity of about 2.4 × 10−5 Ωcm2 was achieved for V(15 nm)/Al(120 nm)/Ni(20 nm)/Au(40 nm). The lowest contact resistivity is accompanied by formation of two thin interfacial regions consisting of AlN and an Au-rich phase. We suggest that not only the formation of thin interfacial AlN layer is important for a low contact resistance, but also the formation of the Au-rich interface can have a favourable effect on the contact properties.

High-quality dissimilar friction stir welding of Al to steel with no contacting between tool and steel plate

The stirring tools made of steels are easily worn in traditional friction stir welding (FSW) of Al alloy to steels, which limits their wide application in industry. Here, we reported a new FSW method with no contacting between the tool and the steel plate, and an ordinary H13 steel tool can be used in this case. In this study, thickened Al alloy plate was applied during FSW of 1060Al to SUS304 stainless steel. The results showed that a high-quality joint was successfully acquired at an appropriate thickness difference of 0.7 mm between Al and steel plates, where an excellent metallurgical bonding achieved in the Al-steel interface. Microstructure characterization revealed a thin interface layer (< 1 μm) consisted of Al5Fe2 intermetallic compound (IMC) and Al13Fe4 IMC as well as Al-based solid solution with enrichment of Ni. The joint failed at the heat affected zone of Al side with a high strength of 104 MPa (95% of 1060Al). This study brings a low-cost and effective method in FSW of Al alloy and high fusion-point metals, and can realize long-distance and high-quality welding in industry.

Toward a universal description of multiphase turbulence phenomena based on the vorticity transport equation

Understanding the evolution of turbulence in multiphase flows remains a challenge due to the complex inter-phase interactions at different scales. This paper attempts to enlighten the multiphase turbulence phenomenon from a new perspective by exploiting the classical concept of vorticity and its role in the evolution of the turbulent energy cascade. We start with the vorticity transport equations for two different multiphase flow formulations, which are one-fluid and two-fluid models. By extending the decaying homogeneous isotropic turbulence (HIT) problem to the multiphase flow context, we performed two highly resolved simulations of HIT in the presence of (i) a thin interface layer and (ii) homogeneously distributed solid particle. These two configurations allow for the investigation of interfacial turbulence and particulate turbulence, respectively. In addition to the analysis of the global flow characteristic in both cases, we evaluate the spectral contribution of each production/dissipation mechanism in the vorticity transport equation to the distribution of vortical energy (enstrophy) across the scales. We base our discussion on the role of the main inter-phase interaction mechanisms in vorticity transport (i.e., the surface tension for interfacial turbulence and drag force for particulate turbulence) and unveil a similar contribution from these mechanisms to the multiphase turbulence cascade. The results also explain the deviation of kinetic energy and enstrophy spectra of multiphase HIT problems from their single-phase similitudes, confirming the validity of this approach for establishing a universal description of multiphase turbulence.

Electronic structure and origin of intrinsic defects in sputtered HfTiO2 alloy dielectric on GaAs surface

In this work, we have investigated the electronic structure and electrical properties of sputter-deposited high-k dielectrics grown on p-GaAs substrate with post-deposition annealing at 500 °C/N2 ambient. Capacitance-voltage results show that co-sputtered amorphous-HfTiO2 alloy dielectric can reduce interfacial dangling bonds. HRTEM and AR- X-ray photoelectron spectroscopy results confirmed the formation of a thin interfacial layer during sputter deposition. At the atomistic level, the surface reaction and electronic interface structure were investigated by density-functional theory (DFT) calculations. Using the HSE functional, theoretical calculations of bulk HfO2, a-TiO2, and HfTiO2 band gaps are found to be 5.27, 2.61, and 4.03 eV, respectively.

Ohmic contact morphology improvement with reduced resistance using Si/Au/Ti/Al/Ni/Au (AlGaN) and Si/Au/Ti/Al/Ni/Au (InAlN) stack layers in III-Nitride HEMTs

This article reports a Ti/Al-based ohmic contact utilizing a thin interfacial Au layer for improved morphology, edge acuity and low contact resistance for applications to III-Nitride high electron mobility transistors (HEMTs). Conventional Ti/Al contacts are based on a metal stack of the form Ti/Al/X/Au, where X is any suitable barrier layer such as Ni. The formation of ohmic contact in GaN and its alloy systems is governed by the formation of TiN during annealing; Au inter-diffusion during annealing also assists the formation of TiN islands and aids in reducing the contact resistance. Furthermore, inter-metallic phase formation between Ti and Al lowers the contact resistance. It is observed that the contact surface morphology strongly depends on the top Au layer thickness. Insertion of a very thin Au layer (2–3 nm) has drastically improved the surface quality with the achievement of contact resistance as low as 0.36 Ω mm and a specific contact resistance of 2.4 × 10−6 Ω cm2 on AlGaN/GaN HEMT. The reduction in contact resistance is due to the formation of more conducting intermetallic phases during annealing, which is assisted due to the thin Au layer insertion. Further reduction in the contact resistance to 0.13 Ω mm was also achieved with the introduction of Si as a dopant layer in the reported metal scheme. The measured rms surface roughness was reduced to ∼8 nm from 0.12 µm in comparison to the conventional ohmic contact.

The plasticizer-free composite block copolymer electrolytes for ultralong lifespan all-solid-state lithium-metal batteries

Solid polymer electrolytes (SPEs) are regarded as one of the most promising substitutes for liquid electrolytes to construct highly safe electrochemical energy storage. While liquid plasticizers are frequently employed in SPEs to enhance ionic conductivity, it is inevitably accompanied by a deficiency in safety. Herein, we report plasticizer-free composite block copolymer electrolytes (BCEs) with conductive nanodomains for ultralong lifespan all-solid-state Li-metal batteries (ASSLBs). The composite BCEs with poly(ether-block-amide) (Pebax) block copolymer as a conductive framework and polyethylene glycol dimethyl ether (PEGDE) as a regulator, can connect and manipulate the highly conductive nanodomains. Compared with homopolymer poly(ethylene oxide) (PEO), the conductive nanodomains in composite BCEs with tunable size can manipulate the Li+ transport channel, effectively enhancing the Li+ conductivity and homogenizing the Li+ deposition. In addition, the thin and dense hybrid solid electrolyte interface (SEI) layer, as well as the potent mechanical strength of composite BCEs, can synergistically suppress the dendrite growth. Therefore, the all-solid-state LiFePO4/Li cells achieve impressive electrochemical performance with a tiny capacity reduction of 0.0127% per cycle for more than 1350 cycles at 0.5 C. This work aims to give impetus to the development of practical ASSLBs which meet the demands for high safety, long lifespan, and mass production.

Integrating Bi@C Nanospheres in Porous Hard Carbon Frameworks for Ultrafast Sodium Storage.

Sodium-ion batteries (SIBs) have emerged as an alternative technology because of their merits in abundance and cost. Realizing their real applications, however, remains a formidable challenge. One is that among the limitations of anode materials, the alloy-type candidates tolerate fast capacity fading during cycling. Here, a 3D framework superstructure assembled with carbon nanobelt arrays decorated with a metallic bismuth (Bi) nanospheres coated carbon layer by thermolysis of Bi-based metal-organic framework nanorods is synthesized as an anode material for SIBs. Due to the unique structural superiority, the anode design promotes excellent sodium-storage performance in terms of high capacity, excellent cycling stability, and ultrahigh rate capability up to 80Ag-1 with a capacity of 308.8mAhg-1 . The unprecedented sodium-storage ability is not only attributed to the unique hybrid architecture, but also to the production of a homogeneous and thin solid electrolyte interface layer and the formation of uniform porous nanostructures during cycling in the ether-based electrolyte. Importantly, deeper understanding of the underlying cause of the performance improvement is illuminated, which is vital to provide the theoretical basis for application of SIBs.