Electrostatic Shielding Boosts Electrochemical Performance of Alloy-Type Anode Materials of Sodium-Ion Batteries.

The applications of alloy-type anode materials for Na-ion batteries are always obstructed by enormous volume variation upon cycles. Here, K+ ions are introduced as an electrolyte additive to improve the electrochemical performance via electrostatic shielding, using Sn microparticles (µ-Sn) as a model. Theoretical calculations and experimental results indicate that K+ ions are not incorporated in the electrode, but accumulate on some sites. This accumulation slows down the local sodiation at the "hot spots", promotes the uniform sodiation and enhances the electrode stability. Therefore, the electrode maintains a high specific capacity of 565 mAh g-1 after 3000 cycles at 2 A g-1 , much better than the case without K+ . The electrode also remains an areal capacity of ≈3.5 mAh cm-2 after 100 cycles. This method does not involve time-consuming preparation, sophisticated instruments and expensive reagents, exhibiting the promising potential for other anode materials.

Sb nanocrystal-anchored hollow carbon microspheres for high-capacity and high-cycling performance lithium-ion batteries.

There is a great need to develop sustainable and clean energy storage devices and systems of high-energy and high-capacity densities. In this work, we synthesize antimony (Sb) nanocrystal-anchored hollow carbon microspheres (Sb@HCMs) via the calcination of cultivated yeast cells and the reduction of SbCl3 in an ethylene glycol solution on the surface of hollow carbon microspheres. The Sb@HCMs possess hollow and porous structure, and the Sb is present in the form of nanocrystals. Using the Sb@HCMs as the active-electrode material, we assemble lithium (Li)-ion half cells and full cells and investigate their electrochemical performance. The Li-ion half cells possess a charge capacity of 605 mA h g-1 after 100 cycles at a current density of 100 mA g-1 and a charge capacity of 469.9 mA h g-1 at a current density up to 1600 mA g-1, which is much higher than the theoretical capacity of 372 mA h g-1 for commercial graphite electrode. The Li-ion full cells with Sb@HCMs//LiCoO2 deliver a charge capacity of 300 mA h g-1 at a current density of 0.2 A g-1 after 50 cycles, and have potential in applications of energy storage.

Rayleigh-Instability-Induced Bismuth Nanorod@Nitrogen-Doped Carbon Nanotubes as A Long Cycling and High Rate Anode for Sodium-Ion Batteries.

Sodium-ion battery (SIB) as one of the most promising large-scale energy storage devices has drawn great attention in recent years. However, the development of SIBs is limited by the lacking of proper anodes with long cycling lifespans and large reversible capacities. Here we present rational synthesis of Rayleigh-instability-induced bismuth nanorods encapsulated in N-doped carbon nanotubes (Bi@N-C) using Bi2S3 nanobelts as the template for high-performance SIB. The Bi@N-C electrode delivers superior sodium storage performance in half cells, including a high specific capacity (410 mA h g-1 at 50 mA g-1), long cycling lifespan (1000 cycles), and superior rate capability (368 mA h g-1 at 2 A g-1). When coupled with homemade Na3V2(PO4)3/C in full cells, this electrode also exhibits excellent performances with high power density of 1190 W kg-1 and energy density of 119 Wh kg-1total. The exceptional performance of Bi@N-C is ascribed to the unique nanorod@nanotube structure, which can accommodate volume expansion of Bi during cycling and stabilize the solid electrolyte interphase layer and improve the electronic conductivity.

Hierarchical MoS2 @Carbon Microspheres as Advanced Anodes for Li-Ion Batteries.

Hierarchical hybridized nanocomposites with rationally constructed compositions and structures have been considered key for achieving superior Li-ion battery performance owing to their enhanced properties, such as fast lithium ion diffusion, good collection and transport of electrons, and a buffer zone for relieving the large volume variations during cycling processes. Hierarchical MoS2 @carbon microspheres (HMCM) have been synthesized in a facile hydrothermal treatment. The structure analyses reveal that ultrathin MoS2 nanoflakes (ca. 2-5 nm) are vertically supported on the surface of carbon nanospheres. The reversible capacity of the HMCM nanocomposite is maintained at 650 mA h g(-1) after 300 cycles at 1 A g(-1) . Furthermore, the capacity can reach 477 mA h g(-1) even at a high current density of 4 A g(-1) . The outstanding electrochemical performance of HMCM is attributed to the synergetic effect between the carbon spheres and the ultrathin MoS2 nanoflakes. Additionally, the carbon matrix can supply conductive networks and prevent the aggregation of layered MoS2 during the charge/discharge process; and ultrathin MoS2 nanoflakes with enlarged surface areas, which can guarantee the flow of the electrolyte, provide more active sites and reduce the diffusion energy barrier of Li(+) ions.

Advancements in aqueous zinc-iodine batteries: a review.

Aqueous zinc-iodine batteries stand out as highly promising energy storage systems owing to the abundance of resources and non-combustible nature of water coupled with their high theoretical capacity. Nevertheless, the development of aqueous zinc-iodine batteries has been impeded by persistent challenges associated with iodine cathodes and Zn anodes. Key obstacles include the shuttle effect of polyiodine and the sluggish kinetics of cathodes, dendrite formation, the hydrogen evolution reaction (HER), and the corrosion and passivation of anodes. Numerous strategies aimed at addressing these issues have been developed, including compositing with carbon materials, using additives, and surface modification. This review provides a recent update on various strategies and perspectives for the development of aqueous zinc-iodine batteries, with a particular emphasis on the regulation of I2 cathodes and Zn anodes, electrolyte formulation, and separator modification. Expanding upon current achievements, future initiatives for the development of aqueous zinc-iodine batteries are proposed, with the aim of advancing their commercial viability.

Bi Nanospheres Embedded in N-Doped Carbon Nanowires Facilitate Ultrafast and Ultrastable Sodium Storage.

Sodium ion batteries (SIBs) are considered as the ideal candidates for the next generation of electrochemical energy storage devices. The major challenges of anode lie in poor cycling stability and the sluggish kinetics attributed to the inherent large Na+ size. In this work, Bi nanosphere encapsulated in N-doped carbon nanowires (Bi@N-C) is assembled by facile electrospinning and carbonization. N-doped carbon mitigates the structure stress/strain during alloying/dealloying, optimizes the ionic/electronic diffusion, and provides fast electron transfer and structural stability. Due to the excellent structure, Bi@N-C shows excellent Na storage performance in SIBs in terms of good cycling stability and rate capacity in half cells and full cells. The fundamental mechanism of the outstanding electrochemical performance of Bi@N-C has been demonstrated through synchrotron in-situ XRD, atomic force microscopy, ex-situ scanning electron microscopy (SEM) and density functional theory (DFT) calculation. Importantly, a deeper understanding of the underlying reasons of the performance improvement is elucidated, which is vital for providing the theoretical basis for application of SIBs.

In Situ Molecular Engineering Strategy to Construct Hierarchical MoS2 Double-Layer Nanotubes for Ultralong Lifespan "Rocking-Chair" Aqueous Zinc-Ion Batteries.

Rechargeable aqueous zinc ion batteries (AZIBs) have gained considerable attention owing to their low cost and high safety, but dendrite growth, low plating/stripping efficiency, surface passivation, and self-erosion of the Zn metal anode are hindering their application. Herein, a one-step in situ molecular engineering strategy for the simultaneous construction of hierarchical MoS2 double-layer nanotubes (MoS2-DLTs) with expanded layer-spacing, oxygen doping, structural defects, and an abundant 1T-phase is proposed, which are designed as an intercalation-type anode for "rocking-chair" AZIBs, avoiding the Zn anode issues and therefore displaying a long cycling life. Benefiting from the structural optimization and molecular engineering, the Zn2+ diffusion efficiency and interface reaction kinetics of MoS2-DLTs are enhanced. When coupled with a homemade ZnMn2O4 cathode, the assembled MoS2-DLTs//ZnMn2O4 full battery exhibited impressive cycling stability with a capacity retention of 86.6% over 10 000 cycles under 1 A g-1anode, outperforming most of the reported "rocking-chair" AZIBs. The Zn2+/H+ cointercalation mechanism of MoS2-DLTs is investigated by synchrotron in situ powder X-ray diffraction and multiple ex situ characterizations. This research demonstrates the feasibility of MoS2 for Zn-storage anodes that can be used to construct reliable aqueous full batteries.

Molten salt-assisted synthesis of bismuth nanosheets with long-term cyclability at high rates for sodium-ion batteries.

Bismuth is a promising anode material for sodium-ion batteries (SIBs) due to its high capacity and suitable working potential. However, the large volume change during alloying/dealloying would lead to poor cycling performance. Herein, we have constructed a 3D hierarchical structure assembled by bismuth nanosheets, addressing the challenges of fast kinetics, and providing efficient stress and strain relief room. The uniform bismuth nanosheets are prepared via a molten salt-assisted aluminum thermal reduction method. Compared with the commercial bismuth powder, the bismuth nanosheets present a larger specific surface area and interlayer spacing, which is beneficial for sodium ion insertion and release. As a result, the bismuth nanosheet anode presents excellent sodium storage properties with an ultralong cycle life of 6500 cycles at a high current density of 10 A g-1, and an excellent capacity retention of 87% at an ultrahigh current rate of 30 A g-1. Moreover, the full SIBs that paired with the Na3V2(PO4)3/rGO cathode exhibited excellent performance. This work not only presents a novel strategy for preparing bismuth nanosheets with significantly increased interlayer spacing but also offers a straightforward synthesis method utilizing low-cost precursors. Furthermore, the outstanding performance demonstrated by these nanosheets indicates their potential for various practical applications.

Cation Defect-Engineered Boost Fast Kinetics of Two-Dimensional Topological Bi2 Se3 Cathode for High-Performance Aqueous Zn-Ion Batteries.

The challenge with aqueous zinc-ion batteries (ZIBs) lies in finding suitable cathode materials that can provide high capacity and fast kinetics. Herein, two-dimensional topological Bi2 Se3 with acceptable Bi-vacancies for ZIBs cathode (Cu-Bi2-x Se3 ) is constructed through one-step hydrothermal process accompanied by Cu heteroatom introduction. The cation-deficient Cu-Bi2-x Se3 nanosheets (≈4 nm) bring improved conductivity from large surface topological metal states contribution and enhanced bulk conductivity. Besides, the increased adsorption energy and reduced Zn2+ migration barrier demonstrated by density-functional theory (DFT) calculations illustrate the decreased Coulombic ion-lattice repulsion of Cu-Bi2-x Se3 . Therefore, Cu-Bi2-x Se3 exhibits both enhanced ion and electron transport capability, leading to more carrier reversible insertion proved by in situ synchrotron X-ray diffraction (SXRD). These features endow Cu-Bi2-x Se3 with sufficient specific capacity (320 mA h g-1 at 0.1 A g-1 ), high-rate performance (97 mA h g-1 at 10 A g-1 ), and reliable cycling stability (70 mA h g-1 at 10 A g-1 after 4000 cycles). Furthermore, quasi-solid-state fiber-shaped ZIBs employing the Cu-Bi2-x Se3 cathode demonstrate respectable performance and superior flexibility even under high mass loading. This work implements a conceptually innovative strategy represented by cation defect design in topological insulator cathode for achieving high-performance battery electrochemistry.

Branched mesoporous Mn3O4 nanorods: facile synthesis and catalysis in the degradation of methylene blue.

Branched MnOOH nanorods with diameters in the range of 50-150 nm and lengths of up to tens of micrometers were prepared by using potassium permanganate (KMnO(4)) and PEG 400 (PEG=polyethylene glycol) as starting materials through a simple hydrothermal process at 160 °C. After annealing at 300 °C under a N(2) atmosphere for 5 h, MnOOH nanorods became gradually dehydrated and transformed into mesoporous Mn(3)O(4) nanorods with a slight size-shrinking. The as-obtained mesoporous Mn(3)O(4) nanorods had an average surface area of 32.88 m(2) g(-1) and a mean pore size of 3.7 nm. Through tuning the experimental parameters, such as the annealing atmosphere and temperature, ß-MnO(2), Mn(2)O(3), Mn(3)O(4), MnO, and Mn(5)O(8) were selectively produced. Among these structures, mesoporous Mn(3)O(4) nanorods were efficient for the catalytic degradation of methylene blue (MB) in the presence of H(2)O(2) at 80 °C.

A Quasi-Double-Layer Solid Electrolyte with Adjustable Interphases Enabling High-Voltage Solid-State Batteries.

Increasing the energy density and long-term cycling stability of lithium-ion batteries necessitates the stability of electrolytes under high/low voltage application and stable electrode/electrolyte interfacial contact. However, neither a single polymer nor liquid electrolyte can realize this due to their limited internal energy gap, which cannot avoid lithium-metal deposition and electrolyte oxidation simultaneously. Herein, a novel type of quasi-double-layer composite polymer electrolytes (QDL-CPEs) is proposed by using plasticizers with high oxidation stability (propylene carbonate) and high reduction stability (diethylene glycol dimethyl ether) in a poly(vinylidene fluoride) (PVDF)-based electrolyte composites. In-situ-polymerized propylene carbonate can function as a cathode electrolyte interface (CEI) film, which can enhance the antioxidant ability. The nucleophilic substitution reaction between diethylene glycol dimethyl ether and PVDF increases the reduction stability of the electrolyte on the anodic side, without the formation of lithium dendrites. The QDL-CPEs has high ionic conductivity, an enhanced electrochemical reaction window, adjustable electrode/electrolyte interphases, and no additional electrolyte-electrolyte interfacial resistance. Thus, this ingenious design of the QDL-CPEs improves the cycling performance of a fabricated LiNi0.8 Co0.1 Mn0.1 O2 (NCM811)//QDL-CPEs//hard carbon full cell at room temperature, paving a new way for designing solid-state battery systems accessible for practical applications.

Zero-Dimensional Cs3BiX6 (X = Br, Cl) Single Crystal Films with Second Harmonic Generation.

The development of atomically thin single crystal films is necessary to potential applications in the 2D semiconductor field, and it is significant to explore new physical properties in low-dimensional semiconductors. Since, zero-dimensional (0D) materials without natural layering are connected by strong chemical bonds, it is challengeable to break symmetry and grow 0D Cs3BiX6 (X = Br, Cl) single crystal thin films. Here, we report the successful growth of 0D Cs3BiX6 (X = Br, Cl) single crystal films using a solvent evaporation crystallization strategy. Their phases and structures are both well evaluated to confirm 0D Cs3BiX6 (X = Br, Cl) single crystal films. Remarkably, the chemical potential dependent morphology evolution phenomenon is observed. It gives rise to morphology changes of Cs3BiBr6 films from rhombus to hexagon as BiBr3 concentration increased. Additionally, the robust second harmonic generation signal is detected in the Cs3BiBr6 single crystal film, demonstrating the broken symmetry originated from decreased dimension or shape change.

Thickness-independent scalable high-performance Li-S batteries with high areal sulfur loading via electron-enriched carbon framework.

Increasing the energy density of lithium-sulfur batteries necessitates the maximization of their areal capacity, calling for thick electrodes with high sulfur loading and content. However, traditional thick electrodes often lead to sluggish ion transfer kinetics as well as decreased electronic conductivity and mechanical stability, leading to their thickness-dependent electrochemical performance. Here, free-standing and low-tortuosity N, O co-doped wood-like carbon frameworks decorated with carbon nanotubes forest (WLC-CNTs) are synthesized and used as host for enabling scalable high-performance Li-sulfur batteries. EIS-symmetric cell examinations demonstrate that the ionic resistance and charge-transfer resistance per unit electro-active surface area of S@WLC-CNTs do not change with the variation of thickness, allowing the thickness-independent electrochemical performance of Li-S batteries. With a thickness of up to 1200 µm and sulfur loading of 52.4 mg cm-2, the electrode displays a capacity of 692 mAh g-1 after 100 cycles at 0.1 C with a low E/S ratio of 6. Moreover, the WLC-CNTs framework can also be used as a host for lithium to suppress dendrite growth. With these specific lithiophilic and sulfiphilic features, Li-S full cells were assembled and exhibited long cycling stability.

Boosting Sodium Storage of Double-Shell Sodium Titanate Microspheres Constructed from 2D Ultrathin Nanosheets via Sulfur Doping.

Sodium-ion batteries (SIBs) have drawn remarkable attention due to their low cost and the practically inexhaustible sodium sources. The major obstacle for the practical application of SIBs is the absence of suitable negative electrode materials with long cycling stability and high rate performance. Here, sulfur-doped double-shell sodium titanate (Na2 Ti3 O7 ) microspheres constructed from 2D ultrathin nanosheets are synthesized via a templating route combined with a low-temperature sulfurization process. The resulting double-shell microspheres deliver a high specific capacity (≈222 mAh g-1 at 1 C), excellent cycling stability (162 mAh g-1 after 15 000 cycles at 20 C), and superior rate capability (122 mAh g-1 at 50 C) as anode for SIBs. The improved electrochemical properties originate from synergistic effects between the unique double-shell nanostructures built from 2D nanosheets architecture and sulfur doping. This synergistic effect not only stabilize Na2 Ti3 O7 -based electrode during the cycling, but also improve the sluggish Na insertion/extraction kinetics by narrowing the bandgap of Na2 Ti3 O7 . The synthesis strategy proposed here can be developed into a technical rationale for generating high-performance sodium-storage devices.

Defect Sites-Rich Porous Carbon with Pseudocapacitive Behaviors as an Ultrafast and Long-Term Cycling Anode for Sodium-Ion Batteries.

Room-temperature sodium-ion batteries have been regarded as promising candidates for grid-scale energy storage due to their low cost and the wide distribution of sodium sources. The main scientific challenge for their practical application is to develop suitable anodes with long-term cycling stability and high rate capacity. Here, novel hierarchical three-dimensional porous carbon materials are synthesized through an in situ template carbonization process. Electrochemical examination demonstrates that carbonization temperature is a key factor that affects Na+-ion-storage performance, owing to the consequent differences in surface area, pore volume, and degree of crystallinity. The sample obtained at 600 °C delivers the best sodium-storage performance, including long-term cycling stability (15 000 cycles) and high rate capacity (126 mAh g-1 at 20 A g-1). Pseudocapacitive behavior in the Na+-ion-storage process has been confirmed and studied via cyclic voltammetry. Full cells based on the porous carbon anode and Na3V2(PO4)3-C cathode also deliver good cycling stability (400 cycles). Porous carbon, combining the merits of high energy density and extraordinary pseudocapacitive behavior after cycling stability, can be a promising replacement for battery/supercapacitors hybrid and suggest a design strategy for new energy-storage materials.

Synergistically Enhanced Interfacial Interaction to Polysulfide via N,O Dual-Doped Highly Porous Carbon Microrods for Advanced Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries have received tremendous attention because of their extremely high theoretical capacity (1672 mA h g-1) and energy density (2600 W h kg-1). Nevertheless, the commercialization of Li-S batteries has been blocked by the shuttle effect of lithium polysulfide intermediates, the insulating nature of sulfur, and the volume expansion during cycling. Here, hierarchical porous N,O dual-doped carbon microrods (NOCMs) were developed as sulfur host materials with a large pore volume (1.5 cm3 g-1) and a high surface area (1147 m2 g-1). The highly porous structure of the NOCMs can act as a physical barrier to lithium polysulfides, while N and O functional groups enhance the interfacial interaction to trap lithium polysulfides, permitting a high loading amount of sulfur (79-90 wt % in the composite). Benefiting from the physical and chemical anchoring effect to prevent shuttling of polysulfides, S@NOCMs composites successfully solve the problems of low sulfur utilization and fast capacity fade and exhibit a stable reversible capacity of 1071 mA h g-1 after 160 cycles with nearly 100% Coulombic efficiency at 0.2 C. The N,O dual doping treatment to porous carbon microrods paves a way toward rational design of high-performance Li-S cathodes with high energy density.

One-Dimensional Yolk-Shell Sb@Ti-O-P Nanostructures as a High-Capacity and High-Rate Anode Material for Sodium Ion Batteries.

Development of high energy/power density and long cycle life of anode materials is highly desirable for sodium ion batteries, because graphite anode cannot be used directly. Sb stands out from the potential candidates, due to high capacity, good electronic conductivity, and moderate sodiation voltage. Here, one-dimensional yolk-shell Sb@Ti-O-P nanostructures are synthesized by reducing core-shell Sb2O3@TiO2 nanorods with NaH2PO2. This structure has Sb nanorod as the core to increase the capacity and Ti-O-P as the shell to stabilize the interface between electrolyte and electrode material. The gap between the core and the shell accommodates the volume change during sodiation/desodiation. These features endow the structure outstanding performances. It could deliver a capacity of about 760 mA h g-1 after 200 cycles at 500 mA g-1, with a capacity retention of about 94%. Even at 10 A g-1, the reversible capacity is still at 360 mA h g-1. The full battery of Sb@Ti-O-P//Na3V2(PO4)3-C presents a high output voltage (∼2.7 V) and a capacity of 392 mA h g-1anode after 150 cycles at 1 A g-1anode.

Double-Walled Sb@TiO2-x Nanotubes as a Superior High-Rate and Ultralong-Lifespan Anode Material for Na-Ion and Li-Ion Batteries.

Double-walled Sb@TiO2- x nanotubes take full advantage of the high capacity of Sb, the good stability of TiO2- x , and their unique interaction, realizing excellent electrochemical performance both in lithium-ion batteries and sodium-ion batteries.

Direct large-scale synthesis of 3D hierarchical mesoporous NiO microspheres as high-performance anode materials for lithium ion batteries.

Hierarchically porous materials are an ideal material platform for constructing high performance Li-ion batteries (LIBs), offering great advantages such as large contact area between the electrode and the electrolyte, fast and flexible transport pathways for the electrolyte ions and the space for buffering the strain caused by repeated Li insertion/extraction. In this work, NiO microspheres with hierarchically porous structures have been synthesized via a facile thermal decomposition method by only using a simple precursor. The superstructures are composed of nanocrystals with high specific surface area, large pore volume, and broad pore size distribution. The electrochemical properties of 3D hierarchical mesoporous NiO microspheres were examined by cyclic voltammetry and galvanostatic charge-discharge studies. The results demonstrate that the as-prepared NiO nanospheres are excellent electrode materials in LIBs with high specific capacity, good retention and rate performance. The 3D hierarchical mesoporous NiO microspheres can retain a reversible capacity of 800.2 mA h g(-1) after 100 cycles at a high current density of 500 mA g(-1).

Facile synthesis of loaf-like ZnMn2O4 nanorods and their excellent performance in Li-ion batteries.

Binary transition metal oxides have been attracting extensive attention as promising anode materials for lithium-ion batteries, due to their high theoretical specific capacity, superior rate performance and good cycling stability. Here, loaf-like ZnMn2O4 nanorods with diameters of 80-150 nm and lengths of several micrometers are successfully synthesized by annealing MnOOH nanorods and Zn(OH)2 powders at 700 °C for 2 h. The electrochemical properties of the loaf-like ZnMn2O4 nanorods as an anode material are investigated in terms of their reversible capacity, and cycling performance for lithium ion batteries. The loaf-like ZnMn2O4 nanorods exhibit a reversible capacity of 517 mA h g(-1) at a current density of 500 mA g(-1) after 100 cycles. The reversible capacity of the nanorods still could be kept at 457 mA h g(-1) even at 1000 mA g(-1). The improved electrochemical performance can be ascribed to the one-dimensional shape and the porous structure of the loaf-like ZnMn2O4 nanorods, which offers the electrode convenient electron transport pathways and sufficient void spaces to tolerate the volume change during the Li(+) intercalation. These results suggest the promising potential of the loaf-like ZnMn2O4 nanorods in lithium-ion batteries.