High-Branched Natural Polysaccharide Flaxseed Gum Binder for Silicon-Based Lithium-Ion Batteries with High Capacity.

Silicon-based anodes heavily depend on the binder to preserve the unbroken electrode structure. In the present work, natural flaxseed gum (FG) is used as a binder of silicon nanoparticles (SiNPs) anode for the first time. Owing to a large number of polar groups and a rich branched structure, this material not only anchors tightly to the surface of SiNPs through bonding interactions but also formed a hydrogen bonding network structure among molecules. As a result, the FG binder can endow the silicon electrode with stable interfacial adhesion and outstanding mechanical properties. In addition, FG with a high viscosity facilitates the homogeneous dispersion of the electrode components. When FG is used as a binder, the cycling performance of the Si anode is greatly improved. After one hundred cycles at an applied current density of 1 A g-1, the electrode continues to display remarkable electrochemical properties with a significant cyclic capacity (2213 mA h g-1) and initial Coulombic efficiency (ICE) of 89.7%.

Compositing pine pollen derived carbon matrix with Na4FeV(PO4)3 nanoparticle for cost-effective sodium-ion batteries cathode.

Na super-ion conductor type material Na3V2(PO4)3 has been widely researched as the cathode of sodium-ion batteries (SIBs) in recent years, but the unsatisfying cost of Na3V2(PO4)3 impedes its wide application in SIBs. In this study, iron element is used to replace part of vanadium in Na3V2(PO4)3 to reduce its expense, and pine pollen is applied for the first time as a very effective carbon source to improve the performance of Na4FeV(PO4)3. The fabricated composite material achieves a capacity of 105 mA h g-1 under 0.2 C and fascinating cycling stability over 94 % under 2 C for 500 cycles and 98 % under 10 C for 1000 cycles. The excellent cycle performance is caused by the involvement of pine pollen that acts as a carbon matrix to enhance the electron conductivity and block the agglomeration of active material effectively, thus the well-dispersed nano sized Na4FeV(PO4)3 shortens the diffusion path of sodium ion and gains a remarkable rate capability. Moreover, the distinguished reversibility during the charge and discharge procedures is ascribed also to the robust structure of Na4FeV(PO4)3. This work provides an efficient route to realize the economic cathode material of SIBs with good performance.

Progressive activation of porous vanadium nitride microspheres with intercalation-conversion reactions toward high performance over a wide temperature range for zinc-ion batteries.

Rechargeable aqueous zinc-ion batteries have great promise for becoming next-generation storage systems, although the irreversible intercalation of Zn2+ and sluggish reaction kinetics impede their wide application. Therefore, it is urgent to develop highly reversible zinc-ion batteries. In this work, we modulate the morphology of vanadium nitride (VN) with different molar amounts of cetyltrimethylammonium bromide (CTAB). The optimal electrode has porous architecture and excellent electrical conductivity, which can alleviate volume expansion/contraction and allow for fast ion transmission during the Zn2+ storage process. Furthermore, the CTAB-modified VN cathode undergoes a phase transition that provides a better framework for vanadium oxide (VOx). With the same mass of VN and VOx, VN provides more active material after phase conversion due to the molar mass of the N atom being less than that of the O atom, thus increasing the capacity. As expected, the cathode displays an excellent electrochemical performance of 272 mAh g-1 at 5 A g-1, high cycling stability up to 7000 cycles, and excellent performance over a wide temperature range. This discovery creates new possibilities for the development of high-performance multivalent ion aqueous cathodes with rapid reaction mechanisms.

F-doped TiO2(B)/reduced graphene for enhanced capacitive lithium-ion storage.

A composite of F-doped TiO2(B) and reduced graphene oxide (F-TiO2(B)/rGO) was successfully synthesized via a one-step hydrothermal route. It was found that the introduction of F ions in the synthetic process has led to the uniform dispersion of TiO2(B) on rGO nanosheets. The F ions have also been doped into the lattice of TiO2(B), which greatly improved the conductivity of the materials. Consequently, this composite delivered a large capacity of 249.4 mA h g-1 at 0.2 A/g. It also demonstrated a capacity of 203.1 mA h g-1 and an excellent capacity retention of 96% after 500 cycles even at a high current density of 2 A/g.

Self-Powered Disinfection Using Triboelectric, Conductive Wires of Metal-Organic Frameworks.

Efficient water disinfection is vitally needed in rural and disaster-stricken areas lacking power supplies. However, conventional water disinfection methods strongly rely on external chemical input and reliable electricity. Herein, we present a self-powered water disinfection system using synergistic hydrogen peroxide (H2O2) assisted electroporation mechanisms driven by triboelectric nanogenerators (TENGs) that harvest electricity from the flow of water. The flow-driven TENG, assisted by power management systems, generates a controlled output with aimed voltages to drive a conductive metal-organic framework nanowire array for effective H2O2 generation and electroporation. The injured bacteria caused by electroporation can be further damaged by facile diffused H2O2 molecules at high throughput. A self-powered disinfection prototype enables complete disinfection (>99.9999% removal) over a wide range of flows up to 3.0 × 104 L/(m2 h) with low water flow thresholds (200 mL/min; ∼20 rpm). This rapid, self-powered water disinfection method is promising for pathogen control.

Cube-like anatase TiO2 mesocrystals as effective electron-transporting materials toward high-performance perovskite solar cells.

Electron-transporting materials (ETMs) with higher carrier mobility and a suitable band gap structure play a significant role in determining the photovoltaic performance of perovskite solar cells (PSCs). Herein, cube-like mesoporous single-crystal anatase TiO2 (Meso-TiO2) nanoparticles synthesized by using a facile hydrothermal method were utilized as an efficient ETM for PSCs. The superior semiconducting properties of the Meso-TiO2 based ETM enabled the best power conversion efficiency (PCE) of 20.05% for a PSC. Moreover, the device retained 80% of its initial PCE after being stored in ambient conditions for 20 days under 25 ± 5% relative humidity. In contrast to the commercial TiO2 ETM, the Meso-TiO2 ETM based PSC showed a distinguished interface with better interfacial conditions and improved carrier extraction originating from the cube-like mesoporous single-crystal anatase TiO2 ETM.

Iodine-doped g-C3N4 modified zinc titanate electron transporting layer for highly efficient perovskite solar cells.

The development of excellent ternary metal oxides as electron transporting layers (ETLs) is highly challenging for perovskite solar cells (PSCs). In this study, ZnTiO3 (ZTO) nanoparticles are synthesized via a facile sol-gel method, and used as an ETL in PSCs. Furthermore, for the first time, iodine-doped g-C3N4 (ICN) is introduced into ZnTiO3-based ETL as additive via a glass-assisted annealing route. Characterizations demonstrate that the ZnTiO3-based ETL with the addition of ICN will enhance the PCE, which is attributed to the improved crystalline quality and more favorable energy level alignment. Moreover, the existence of ICN will strengthen the interfacial cohesion between perovskite layer and ETL as well as retard the perovskite crystals from decomposing, leading to the high quality capping light-harvesting layer upon ICN-modified ZnTiO3 (ZTO-ICN) film. Consequently, a champion device fabricated with ZTO-ICN ETL achieves a maximum PCE of 19.17 % with an open circuit voltage (Voc) of 1.012 V, a short-circuit current density (Jsc) of 26.32 mA cm-2 and a fill factor (FF) of 0.720 under AM 1.5 G sunlight (100 mW cm-2).

Sb-Doped metallic 1T-MoS2 nanosheets embedded in N-doped carbon as high-performance anode materials for half/full sodium/potassium-ion batteries.

Metal 1T phase molybdenum disulfide (1T-MoS2) is being actively considered as a promising anode due to its high conductivity, which can improve electron transfer. Herein, we elaborately designed stable Sb-doped metallic 1T phase molybdenum sulfide (1T-MoS2-Sb) with a few-layered nanosheet structure via a simple calcination technique. The N-doping of the carbon and Sb-doping induce the formation of T-phase MoS2, which not only effectively enhances the entire stability of the structure, but also improves its cycling performance and stability. When employed as an anode of sodium-ion batteries (SIBs), 1T-MoS2-Sb exhibits a reversible capacity of 493 mA h g-1 at 0.1 A g-1 after 100 cycles and delivers prominent long-term performance (253 mA h g-1 at 1 A g-1 after 2200 cycles) along with decent rate capability. Paired with a Na3V2(PO4)3 cathode, it displays a superior capacity of 242 mA h g-1 at 0.5 A g-1 over 100 cycles, which is one of the best performances of a MoS2-based full cell for SIBs. Employed as the anode for potassium-ion batteries (PIBs), it exhibits a satisfactory specific capacity of 343 mA h g-1 at 0.1 A g-1 after 100 cycles. This facile strategy will provide new insights for designing T-phase advanced anode materials for SIBs/PIBs.

Ionic Liquid-Assisted Crystallization and Defect Passivation for Efficient Perovskite Solar Cells with Enhanced Open-Circuit Voltage.

Perovskite materials have demonstrated many excellent properties in next-generation photovoltaic devices, but the intrinsic defects and the quality of perovskite film still limit the performance and stability of PSCs. Here, 1,3-dimethylimidazolium iodide (DMII) ionic liquid was employed as an additive to passivate the various defects and produce the high-quality perovskite film with enlarged grain sizes. DMII could act as an "ionic stabilizer" for passivating the point defects including the vacancies defects of organic cations and halogen anions of perovskite. At the same time, the extra problematic PbI2 on surfaces and at grain boundaries of the perovskite film could also be reacted by DMII, leading to the reduction of recombination centers and trap states. On the other hand, the DMII ionic liquid with a "Ostwald ripening effect" could retard the crystallization process of perovskite crystals and yield better film quality with higher crystallinity, smoother morphology and larger grains. As a result, the optimal device achieved a champion power conversion efficiency (PCE) of 20.4 %. Particularly, the modified devices demonstrated a significant elevation in open-circuit voltage from 1.03 to 1.10 V. The hydrophobicity of perovskite films modified by DMII was enhanced and the un-encapsulated DMII devices retained 91 % of their initial PCE after aging 60 days under 15±5 % relative humidity.

High stability and high performance nitrogen doped carbon containers for lithium-ion batteries.

For a long time, carbon has been an ideal material for various electrochemical energy storage devices and a key component in electrochemical energy storage systems due to its advantages of rich surface states, easy tenability, and good chemical stability. Stable and high-performance carbon materials can support future applications of high specific energy electrodes. Herein and for the first time, we have designed nitrogen-doped carbon hollow containers using oleylamine-coating TiO2 mesocrystals as a precursor with a high specific surface area of 1231 m2 g-1. When applied as an anode for lithium-ion storage, a reversible capacity of 774.5 mA h g-1 is obtained at a rate of 0.5 A g-1 after 200 cycles. Meanwhile, at an even higher rate of 2 A g-1, a capacity of 721.1 mA h g-1 is still achieved after 500 cycles. Moreover, the carbon containers remain structurally intact after a series of cycles. This may be attributed to the nitrogen atoms doped on the carbon surface that can absorb multiple lithium ions and enhance the structural stability. These results provide technical support for the development of high specific energy electrode materials.

High-Rate, Large Capacity, and Long Life Dendrite-Free Zn Metal Anode Enabled by Trifunctional Electrolyte Additive with a Wide Temperature Range.

Aqueous Zn-ion batteries (AZIBs) have been recognized as promising energy storage devices due to their high theoretical energy density and cost-effectiveness. However, side reactions and Zn dendrite generation during cycling limit their practical application. Herein, ammonium acetate (CH3 COONH4 ) is selected as a trifunctional electrolyte additive to enhance the electrochemical performance of AZIBs. Research findings show that NH4 + (oxygen ligand) and CH3 COO- (hydrogenligand) with preferential adsorption on the Zn electrode surface can not only hinder Zn anode directly contact with active H2 O, but also regulate the pH value of the electrolyte, thus suppressing the parasitic reactions. Additionally, the formed SEI is mainly consisted of Zn5 (CO3 )2 (OH)6 with a high Zn2+ transference number, which could achieve a dendrite-free Zn anode by homogenizing Zn deposition. Consequently, the Zn||Zn symmetric batteries with CH3 COONH4 -based electrolyte can operate steadily at an ultrahigh current density of 40 mA cm-2 with a cumulative capacity of 6880 mAh cm-2 , especially stable cycling at -10 °C. The assembled Zn||MnO2 full cell and Zn||activated carbon capacitor also deliver prominent electrochemical reversibility. This work provides unique understanding of designing multi-functional electrolyte additive and promotes a long lifespan at ultrahigh current density for AZIBs.

A Composite of Two Dimensional GeSe2 /Nitrogen-Doped Reduced Graphene Oxide for Enhanced Capacitive Lithium-Ion Storage.

A composite of two-dimensional (2D) GeSe2 nanosheets dispersed on N-doped reduced graphene oxide (GeSe2 /N-rGO) is fabricated via a simple hydrothermal method combined with post-selenization process. The high electronic conductivity and the substantial void spaces of the wrinkled N-rGO can improve the electrical conductivity of the active material and accommodate the volume evolution of GeSe2 nanosheets during the (de)lithiation processes, while GeSe2 nanosheets can reduce ion diffusion length effectively. Meanwhile, the unique layered structure is beneficial to the contact of the active material and electrolyte, and the reversibility of conversion reaction has also been improved. Furthermore, kinetics analysis reveals a pseudocapacitance-dominated Li+ -storage mechanism at high rates. In-situ X-ray diffraction analysis discloses that the conversion reaction has played a certain part in Li+ -storage. Thus, the GeSe2 /N-rGO composite delivers excellent rate capability and good long-term stability with a high reversible capacity of 711.0 mA h g-1 after 2000 cycles at 1 A g-1 .

Structure Engineering of BiSbSx Nanocrystals Embedded within Sulfurized Polyacrylonitrile Fibers for High Performance of Potassium-Ion Batteries.

Potassium-ion batteries (PIBs) are regarded as promising candidates in next-generation energy storage technology; however, the electrode materials in PIBs are usually restricted by the shortcomings of large volume expansion and poor cycling stability stemming from a high resistance towards diffusion and insertion of large-sized K ions. In this study, BiSbSx nanocrystals are rationally integrated with sulfurized polyacrylonitrile (SPAN) fibres through electrospinning technology with an annealing process. Such a unique structure, in which BiSbSx nanocrystals are embedded inside the SPAN fibre, affords multiple binding sites and a short diffusion length for K+ to realize fast kinetics. In addition, the molecular structure of SPAN features robust chemical interactions for stationary diffluent discharge products. Thus, the electrode demonstrates a superior potassium storage performance with an excellent reversible capacity of 790 mAh g-1 (at 0.1 A g-1 after 50 cycles) and 472 mAh g-1 (at 1 A g-1 after 2000 cycles). It's one of the best performances for metal dichalcogenides anodes for PIBs to date. The unusual performance of the BiSbSx @SPAN composite is attributed to the synergistic effects of the judicious nanostructure engineering of BiSbSx nanocrystals as well as the chemical interaction and confinement of SPAN fibers.

Tin-based metal-phosphine complexes nanoparticles as long-cycle life electrodes for high-performance hybrid supercapacitors.

New tin-based metal-phosphine complexes of [Sn(OH)4(PPh3)2] and [Sn(OH)2(PPh3)2] have been successfully synthesized and used as supercapacitor electrodes for the first time, exhibiting a high specific capacitance, a good rate capability, and an excellent cycling stability. The specific capacitances (highest specific capacitance for tin-based materials) of 1204F g-1 and 764F g-1 for two samples at a current density of 1 A g-1 in 6 M KOH can respectively be achieved, and their capacitance retention remained at 95.1% and 89.2% even after 15,000 cycles at a current density of 10 A g-1. Furthermore, a flexible quasi-solid-state asymmetric supercapacitor composed of Sn(OH)2(PPh3)2 and activated carbon was assembled and exhibited a specific capacitance of 290.6 mF cm-2 at a current density of 1 mA cm-2. More importantly, this device also displayed excellent cyclic stability of ∼100% for 1800 cycles during the galvanostatic charge/discharge process at 5 mF cm-2.

Self-Optimizing Effect in Lithium Storage of GeO2 Induced by Heterointerface Regulation.

Herein, a heterostructural hexagonal@tetragonal GeO2 (HT-GeO2 ) composite has been designed based on density functional theory (DFT) calculations and synthesized via an acidic-heating route dealt with rapid cooling, where the inner hexagonal GeO2 (H-GeO2 ) phase is covered by a porous layer of tetragonal GeO2 (T-GeO2 ) owing to HF etching. Interestingly, the HT-GeO2 electrode has a self-optimizing effect in lithium storage induced by heterointerface regulation, where the porous T-GeO2 layer on the surface of HT-GeO2 can act as not only a Li+ /electron conducting layer, but also a buffer layer, while the inner H-GeO2 phase can react preferentially with Li ions owing to lower intercalation energy, which is confirmed by operando XRD measurement contributing to thorough lithiation for HT-GeO2 . Moreover, the heterointerface can enhance the pseudocapacitance effect, which can boost the Li storage and accelerate the discharge-charge process. As a result, a large capacity of 984 mAh g-1 after 500 cycles at 2 A g-1 and a capacity of 430 mAh g-1 at a high current density of 20 A g-1 are delivered. This work provides an easy and efficient way to improve the cycling stability of the GeO2 anode, and the T-GeO2 phase would be a novel anode material in energy storage devices.

A General Synthesis of Mesoporous Hollow Carbon Spheres with Extraordinary Sodium Storage Kinetics by Engineering Solvation Structure.

Porous and hollow carbon materials have great superiority and prospects in electrochemical energy applications, especially for surface charge storage due to the high active surface. Herein, a general strategy is developed to synthesize mesoporous hollow carbon spheres (MHCS) with controllable texture and compositions by the synergistic effect of dopamine polymerization and metal catalysis (Cu, Bi, Zn). Mesoporous MHCS-Cu and MHCS-Bi are regular spheres, while mesoporous MHCS-Zn possesses an inward concave texture, and simultaneously has a very high surface area of 1675.5 m2 g-1 and lower oxygen content through the catalytic deoxygenation effect. MHCS-Zn displays an exceptional sodium storage kinetics and excellent long cycling life with 171.9 mAh g-1 after 2500 cycles at 5 A g-1 in compatible ether-based electrolytes. Such electrolyte enables enhanced solvated Na+ transport kinetics with appropriate electrostatic interactions at the surface of carbon anode as revealed by molecular dynamics simulations and molecular surface electrostatic potential calculations. Such an anode also displays basically constant capacity working at 0 °C, and still delivers 140 mAh g-1 at 3 A g-1 under -20 °C. Moreover, MHCS-Zn anode is coupled with Na3 V2 (PO4 )3 cathode to construct a hybrid capacitor, which exhibits a high energy density of 145 Wh Kg-1 at a very high power of 8009 W kg-1 .

Defect passivation of a perovskite film by ZnIn2S4 nanosheets for efficient and stable perovskite solar cells.

The defects of a perovskite film were first passivated by two dimensional ZnIn2S4 nanosheets, the non-radiation recombination at interfaces was suppressed and the contact of the perovskite film with water vapour in the air was avoided, resulting in a high efficiency of 20.55%.

Facile fabrication of WS2 nanocrystals confined in chlorella-derived N, P co-doped bio-carbon for sodium-ion batteries with ultra-long lifespan.

Sodium-ion batteries (SIBs) have been regarded as a promising substitute for lithium-ion batteries but there are still formidable challenges in developing an anode material with adequate lifespan and outstanding rate performance. Transition metal dichalcogenides (TMDs) are promising anode materials for SIBs due to their high theoretical capacities. However, their severe volume expansions and low electronic conductivity impede their practical developments. In addition, the synthesis of energy storage materials from waste biomass has aroused extensive attention. Herein, we synthesize WS2 nanocrystals embedded in N and P co-doped biochar via a facile bio-sorption followed by sulphurization, employing waste chlorella as the adsorbent and bio-reactor. The WS2 nanocrystals are beneficial for storing more sodium ions and expediting the transportation of sodium ions, thus improving the capacity and reaction kinetics. Chlorella acts as a reactor and not only inhibits the stacking of WS2 nanocrystals during the synthesis process but also alleviates the mechanical pressure of composite during the charge/discharge process. As a result, the WS2/NPC-2 electrode delivers a high specific capacity (436 mA h g-1 at 0.1 A g-1) and superior rate performance of 311 mA h g-1 at 3 A g-1 for SIBs. It also exhibits excellent stability even up to 6000 cycles at 5 A g-1, which is one of the optimal long-cycle properties reported for WS2-based materials to date.

Low crystalline 1T-MoS2@S-doped carbon hollow spheres as an anode material for Lithium-ion battery.

A low crystalline 1T-MoS2@S-doped carbon (MoS2@SC) composite was successfully synthesized via a facile hydrothermal process. The composite is comprised by few-layer 1T-MoS2 nanosheets covered by an amorphous carbon layer with an expanded interlayer d-spacing of 1.01 nm. This structure is conducive to the fast transport of lithium-ions and volume accommodation during the charge-discharge process when the composite is applied as an anode material for LIBs. Additionally, the high conductivity and layered structure of 1T-MoS2 also facilitate fast of ion/electron transport, contributing to the improvement of the electrochemical properties. Therefore, this material demonstrated a high rate performance and excellent cycling stability, with the capacities of 847 and 622 mA h g-1 achieved at the current densities of 0.2 A g-1 and 2 A g-1, respectively. Even at a larger current density of 2 A g-1, MoS2@SC delivered a high reversible capacity of 659 mA h g-1 with an average capacity loss of 0.006% per cycle after 500 cycles.

A new neodymium-phosphine compound for supercapacitors with long-term cycling stability.

A new neodymium-phosphine compound (Nd-(Ph)3P) was used for the first time as an electrode for supercapacitors and exhibited an extraordinary capacitance of 951 F g-1 at 0.5 A g-1 with a high capacitance retention of 96% after 10 000 cycles at 10 A g-1, which is the highest capacitance for rare earth based materials in SCs. Such an excellent performance might be due to the fact that this material can provide plenty of electron-active sites for charge storage and electrolyte diffusion can be efficiently promoted.