Salt-Assisted Recovery of Sodium Metal Anodes for High-Rate Capability Sodium Batteries.

Rechargeable sodium metal batteries are considered to be one of the most promising high energy density and cost-effective electrochemical energy storage systems. However, their practicality is constrained by the high reactivity of sodium metal anodes that readily brings about excessive accumulation of inactive Na species on the surface, either by chemical reactions with oxygen and moisture during electrode handling or through electrochemical processes with electrolytes during battery operation. Herein, this paper reports on an alkali, salt-assisted, assembly-polymerization strategy to recover Na activity and to reinforce the solid-electrolyte interphase (SEI) of sodium metal anodes.

Orderly Arranged Dipoles Regulate Anion-Derived Solid-Electrolyte Interphase for Stable Lithium Metal Chemistry.

Lithium (Li) metal batteries are considered the most promising high-energy-density electrochemical energy storage devices of the next generation. However, the unstable solid-electrolyte interphase (SEI) derived from electrolytes usually leads to high impedance, Li dendrites growth, and poor cyclability. Herein, the ferroelectric BaTiO with orderly arranged dipoles (BTOV) is integrated into the polypropylene separator as a functional layer.

Effect of Mo Oxides on the Phase Composition and Characteristics of Mo-10Re Pre-Alloyed Powders Co-Reduced with NHReO.

Mo-Re pre-alloyed powders are crucial raw materials in fabricating Mo-Re alloys, and their properties can significantly impact the properties of the resulting alloys. The powders are usually produced by the co-reduction of a mixture of Mo and Re oxides. However, it remains unclear if the overall characteristics of the produced Mo-Re powders rely on the different combinations of the Mo and Re oxide precursors.

A separator modified by barium titanate with macroscopic polarization electric field for high-performance lithium-sulfur batteries.

The detrimental "shuttling effect" of lithium polysulfides and the sluggish kinetics of the sulfur redox reaction in lithium-sulfur batteries (LSBs) impede the practical application. Considering the high polar chemistry facilitates the anchoring of polysulfides, ferroelectric materials have gradually been employed as functionalized separators to suppress the "shuttling effect". Herein, a functional separator coated with BaTiO with a macroscopic polarization electric field (poled-BaTiO) is designed for retarding the problematic shuttle effect and accelerating redox kinetics.

Integrating a Ferroelectric Interface with a Well-Tuned Electronic Structure in Lithium-Rich Layered Oxide Cathodes for Enhanced Lithium Storage.

Li-rich layered oxides (LLOs) are considered promising candidates for new high-energy-density cathode materials for next-generation power batteries. However, their large-scale applications are largely hindered by irreversible Li/O loss, structural degradation, and interfacial side reactions during cycling. Herein, we demonstrate an integration strategy that tunes the electronic structure by La/Al codoping and constructs a ferroelectric interface on the LLOs surface through BiNaTiO (BNT) coating.

Constructing a Composite Structure by a Gradient Mg Doping Strategy for High-Performance Sodium-Ion Batteries.

Layered P2-NaMnNiO has been considered an attractive cathode material for sodium-ion batteries (SIBs). Nevertheless, it is still burdened with hazardous phase transformation of P2-O2 under high voltage and harmful reactions at the interface of the electrode and electrolyte. These result in unfavorable structural degradation and rapid capacity decay.

Insights into the Enhanced Structural and Thermal Stabilities of Nb-Substituted Lithium-Rich Layered Oxide Cathodes.

Lithium-rich manganese-based layered oxides (LLOs) are considered to be the most promising cathode materials for next-generation lithium-ion batteries (LIBs) for their higher reversible capacity, higher operating voltage, and lower cost compared with those of other commercially available cathode materials. However, irreversible lattice oxygen release and associated severe structural degradation that exacerbate under high temperature and deep delithiation hinder the large-scale application of LLOs. Herein, we propose a strategy to stabilize the layered lattice framework and improve the thermal stability of cobalt-free LiMnNiO by doping with 4d transition metal niobium (Nb).

Engineering Fe-N Coordination Structures for Fast Redox Conversion in Lithium-Sulfur Batteries.

Critical drawbacks, including sluggish redox kinetics and undesirable shuttling of polysulfides (Li S , n = 4-8), seriously deteriorate the electrochemical performance of high-energy-density lithium-sulfur (Li-S) batteries. Herein, these challenges are addressed by constructing an integrated catalyst with dual active sites, where single-atom (SA)-Fe and polar Fe N are co-embedded in nitrogen-doped graphene (SA-Fe/Fe N@NG). The SA-Fe, with plane-symmetric Fe-4N coordination, and Fe N, with triangular pyramidal Fe-3N coordination, in this well-designed configuration exhibit synergistic adsorption of polysulfides and catalytic selectivity for Li S lithiation and Li S delithiation, respectively.

Synthesis, structure, and properties of carbon/carbon composites artificial rib for chest wall reconstruction.

In this work, braided carbon fiber reinforced carbon matrix composites (3D-C/C composites) are prepared by chemical vapor infiltration process. Their composite structure, mechanical properties, biocompatibility, and in vivo experiments are investigated and compared with those of traditional 2.5D-C/C composites and titanium alloys TC4.

Regulating Anion Redox and Cation Migration to Enhance the Structural Stability of Li-Rich Layered Oxides.

Lithium-rich manganese-based layered oxide cathodes (LLOs) with oxygen redox reactions are considered to be potential candidates for the next generation of high-energy-density Li-ion batteries. However, the oxygen redox process that enables ultrahigh specific capacity usually leads to irreversible O release and cation migration, which induce structure degradation and severe capacity/voltage losses and thus limit the commercial application of LLOs. Herein, we successfully synthesized chlorine (Cl)-doped Co-free LLOs (LiMnNiOCl) and analyzed the effect of anion doping on oxygen redox and structure stability of LLOs.

Shift-Twin Option in Eight-Layer Hexagonal Perovskite Niobates BaMNbO.

Two new eight-layer hexagonal perovskites with the composition BaMNbO (M = Fe and Cu) are synthesized by solid-state reaction at 1350-1400 °C. Their crystal structures have been investigated using X-ray and electron diffractions as well as high-resolution transmission electron microscopy. Although both compounds have similar M size, BaFeNbO and BaCuNbO adopt shifted and twinned structures, respectively.

Unraveling Atomically Irreversible Cation Migration in Sodium Layered Oxide Cathodes.

Transition metal (TM)-based layered oxides NaTMO (TM = Fe, Ni, Co, Mn, etc.) have been intensively pursued as high-capacity cathode materials for Na-ion batteries. Nevertheless, they still suffer from fast capacity loss and voltage decay, as a result of the layered structure instability upon extended electrochemical cycling.

An atomic scale study of two-dimensional quasicrystal nucleation controlled by multiple length scale interactions.

Formation of quasicrystal structures has always been mysterious since the discovery of these magic structures. In this work, the nucleation of decagonal, dodecagonal, heptagonal, and octagonal quasicrystal structures controlled by the coupling among multiple length scales is investigated using a dynamic phase-field crystal model. We observe that the nucleation of quasicrystals proceeds through local rearrangement of length scales, i.

Dislocation driven spiral and non-spiral growth in layered chalcogenides.

Two-dimensional materials have shown great promise for implementation in next-generation devices. However, controlling the film thickness during epitaxial growth remains elusive and must be fully understood before wide scale industrial application. Currently, uncontrolled multilayer growth is frequently observed, and not only does this growth mode contradict theoretical expectations, but it also breaks the inversion symmetry of the bulk crystal.

Core-Shell Nanocomposites for Improving the Structural Stability of Li-Rich Layered Oxide Cathode Materials for Li-Ion Batteries.

The structural stability of Li-rich layered oxide cathode materials is the ultimate frontier to allow the full development of these family of electrode materials. Here, first-principles calculations coupled with cluster expansion are presented to investigate the electrochemical activity of phase-separation, core-shell-structured xLiMnO·(1 - x)LiNiCoMnO nanocomposites. The detrimental surface effects of the core region can be countered by the LiMnO shell, which stabilizes the nanocomposites.

8-Layer Shifted Hexagonal Perovskite BaMnNbO: Long-Range Ordering of High-Spin d Mn Layers and Electronic Structure.

A new 8-layer shifted hexagonal perovskite BaMnNbO has been synthesized in air, featuring unusual long-range B-cation ordering with single octahedral high-spin d Mn layers separated by ∼1.9 nm within the corner-sharing octahedral d Nb host, analogous to Ba(Zn/Co)NbO. The large size and charge differences between high-spin Mn and Nb, as well as the out-of-center distortion of NbO octahedra associated with the bonding covalence and second-order Jahn-Teller effect of Nb, drive long-range cationic ordering, thus stabilizing BaMnNbO.

Understanding the Improved Kinetics and Cyclability of a LiMnSiO Cathode with Calcium Substitution.

Limited practical capacity and poor cyclability caused by sluggish kinetics and structural instability are essential aspects that constrain the potential application of LiMnSiO cathode materials. Herein, LiMnCa SiO/C nanoplates are synthesized using a diethylene-glycol-assisted solvothermal method, targeting to circumvent its drawbacks. Compared with the pristine material, the Ca-substituted material exhibits enhanced electrochemical kinetics and improved cycle life performance.

Ab Initio Study on Surface Segregation and Anisotropy of Ni-Rich LiNiCoMnO (NCM) (y ≤ 0.1) Cathodes.

Advances in ex situ and in situ (operando) characteristic techniques have unraveled unprecedented atomic details in the electrochemical reaction of Li-ion batteries. To bridge the gap between emerging evidences and practical material development, an elaborate understanding on the electrochemical properties of cathode materials on the atomic scale is urgently needed. In this work, we perform comprehensive first-principle calculations within the density functional theory + U framework on the surface stability, morphology, and elastic anisotropy of Ni-rich LiNiCoMnO (NCM) (y ≤ 0.

Charge-transfer modified embedded atom method dynamic charge potential for Li-Co-O system.

To overcome the limitation of conventional fixed charge potential methods for the study of Li-ion battery cathode materials, a dynamic charge potential method, charge-transfer modified embedded atom method (CT-MEAM), has been developed and applied to the Li-Co-O ternary system. The accuracy of the potential has been tested and validated by reproducing a variety of structural and electrochemical properties of LiCoO. A detailed analysis on the local charge distribution confirmed the capability of this potential for dynamic charge modeling.

First principles study of the Mn-doping effect on the physical and chemical properties of mullite-family AlSiO.

Transition metal (TM) modification is a common strategy for converting an earth-abundant mineral into a cost-effective catalyst for industrial applications. Among a variety of minerals, AlSiO, which has three phases, andalusite, sillimanite and kyanite, is emerging as a promising candidate for new catalyst development. In this paper, we use Mn to demonstrate the rationale of 3d TM doping at the Al sites in each of these three phases through first-principles calculations and the cluster expansion method.

A kinetic Monte Carlo simulation method of van der Waals epitaxy for atomistic nucleation-growth processes of transition metal dichalcogenides.

Controlled growth of crystalline solids is critical for device applications, and atomistic modeling methods have been developed for bulk crystalline solids. Kinetic Monte Carlo (KMC) simulation method provides detailed atomic scale processes during a solid growth over realistic time scales, but its application to the growth modeling of van der Waals (vdW) heterostructures has not yet been developed. Specifically, the growth of single-layered transition metal dichalcogenides (TMDs) is currently facing tremendous challenges, and a detailed understanding based on KMC simulations would provide critical guidance to enable controlled growth of vdW heterostructures.

Charge Mediated Reversible Metal-Insulator Transition in Monolayer MoTe2 and WxMo1-xTe2 Alloy.

Metal-insulator transitions in low-dimensional materials under ambient conditions are rare and worth pursuing due to their intriguing physics and rich device applications. Monolayer MoTe2 and WTe2 are distinguished from other TMDs by the existence of an exceptional semimetallic distorted octahedral structure (T') with a quite small energy difference from the semiconducting H phase. In the process of transition metal alloying, an equal stability point of the H and the T' phase is observed in the formation energy diagram of monolayer WxMo1-xTe2.