Towards metal selenides: a promising anode for sodium-ion batteries.

Metal selenides have garnered significant attention as promising anode materials for sodium-ion batteries, thanks to their high theoretical capacity, excellent conductivity, and natural abundance. However, their potential is hampered by disappointing capacity retention and unsatisfactory lifespan, primarily attributed to volume expansion and unwanted structural collapse resulting from the insertion and extraction of relatively large Na+ ions during the charge and discharge processes. This feature article provides a brief overview of our endeavors to address the challenges associated with metal selenide-based anode materials, aiming to achieve high-performance electrode materials for sodium-ion batteries. Our strategy encompasses nanostructure design, materials composite engineering, heteroatoms doping, and topography and interface engineering. Additionally, future research directions are also outlined.

Microwave-Assisted Hydrothermal Synthesis of Na3V2(PO4)2F3 Nanocuboid@Reduced Graphene Oxide as an Ultrahigh-Rate and Superlong-Lifespan Cathode for Fast-Charging Sodium-Ion Batteries.

Na3V2(PO4)2F3 (NVPF) has been regarded as a favorable cathode for sodium-ion batteries (SIBs) due to its high voltage and stable structure. However, the limited electronic conductivity restricts its rate performance. NVPF@reduced graphene oxide (rGO) was synthesized by a facile microwave-assisted hydrothermal approach with subsequent calcination to shorten the hydrothermal time. NVPF nanocuboids with sizes of 50-150 nm distributed on rGO can be obtained, delivering excellent electrochemical performance such as a longevity life (a high capacity retention of 85.6% after 7000 cycles at 10 C) and distinguished rate capability (116 mAh g-1 at 50 C with a short discharging/charging time of 1.2 min). The full battery with a Cu2Se anode represents a capacity of 116 mAh g-1 at 0.2 A g-1. The introduction of rGO can augment the electronic conductivity and advance the Na+ diffusion speed, boosting the cycling and rate capability. Besides, the small lattice change (3.3%) and high structural reversibility during the phase transition process between Na3V2(PO4)2F3 and NaV2(PO4)2F3 testified by in situ X-ray diffraction are also advantageous for Na storage behavior. This work furnishes a simple method to synthesize polyanionic cathodes with ultrahigh rate and ultralong lifespan for fast-charging SIBs.

One-step Solid-State Synthesis of V1.13Se2/V2O3 Heterostructure as a High Pseudocapacitance Anode for Fast-Charging Sodium-Ion Batteries.

Sodium-ion batteries (SIBs) offer several benefits, including cost-efficiency and fast-charging characteristics, positioning them as attractive substitutes for lithium-ion batteries in energy storage applications. However, the inferior capacity and cycling stability of electrodes in SIBs necessitate further enhancement due to sluggish reaction kinetics. In this respect, the utilization of heterostructures, which can provide an inherent electric field and abundant active sites on the surface, has emerged as a promising strategy for augmenting the cycling stability and rate features of the electrodes. This work delves into the utilization of V1.13Se2/V2O3 heterostructure materials as anodes, initially fabricated via a simplified one-step solid-state sintering technique. The high pseudocapacitance and low characteristic relaxation time constant give the V1.13Se2/V2O3 heterostructure impressive properties, such as a high capacity of 328.5 mAh g-1 even after 1500 cycles at a high current density of 2 A g-1 and rate capability of 278.9 mAh g-1 at 5 A g-1. Moreover, the assembled sodium-ion full battery delivers a capacity of 118.5 mAh g-1 after 1000 cycles at 1 A g-1. These findings provide novel insight and guidance for the rapid synthesis of heterojunction materials and the advancement of SIBs.

Mn(II) Optimized Sono/Chemodynamic Effect of Porphyrin-Metal-Organic Framework Nanosheets for MRI-Guided Colon Cancer Therapy and Metastasis Suppression.

Sonodynamic therapy (SDT) offers a remarkable non-invasive ultrasound (US) treatment by activating sonosensitizer and generating reactive oxygen species (ROS) to inhibit tumor growth. The development of multifunctional, biocompatible, and highly effective sonosensitizers remains a current priority for SDT. Herein, the first report that Mn(II) ions chelated Gd-TCPP (GMT) nanosheets (NSs) are synthesized via a simple reflux method and encapsulated with pluronic F-127 to form novel sonosensitizers (GMTF). The GMTF NSs produce a high yield of ROS under US irradiation due to the decreased highest occupied molecular orbital-lowest unoccupied molecular orbital gap energy (2.7-1.28 eV). Moreover, Mn(II) ions endow GMTF with a fascinating Fenton-like activity to produce hydroxyl radicals in support of chemodynamic therapy (CDT). It is also effectively used in magnetic resonance imaging (MRI) with high relaxation rate (r 1: 4.401 mM-1 s-1) to track the accumulation of NSs in tumors. In vivo results indicate that the SDT and CDT in combination with programmed cell death protein 1 antibody (anti-PD-1) show effective metastasis prevention effects, and 70% of the mice in the GMTF + US + anti-PD-1 group survived for 60 days. In conclusion, this study develops a sonosensitizer with promising potential for utilizing both MRI-guided SDT and CDT strategies.

2D-Layer-Structure Bi to Quasi-1D-Structure NiBi3 : Structural Dimensionality Reduction to Superior Sodium and Potassium Ion Storage.

Layer-structured bismuth (Bi) is an attractive anode for Na-ion and K-ion batteries due to its large volumetric capacity and suitable redox potentials. However, the cycling stability and rate capability of the Bi anode are restricted by the large volume expansion and sluggish Na/K-storage kinetics. Herein, a structural dimensionality reduction strategy is proposed and developed by converting 2D-layer-structured Bi into a quasi-1D structured NiBi3 with enhanced reaction kinetics and reversibility to realize high-rate and stable cycling performance for Na/K-ion storage. As a proof of concept, the quasi-1D intermetallic NiBi3 with low formation energy, metallic conductivity, and 3D Na/K-ion diffusion pathways delivers outstanding capacity retention of 94.1% (332 mAh g-1 ) after 15 000 cycles for Na-ion storage, and high initial coulombic efficiency of 93.4% with improved capacity retention for K-ion storage. Moreover, investigations on the highly reversible Na/K-storage reaction mechanisms and cycling-driven morphology reconstruction further reveal the origins of the high reversibility and the accommodation to volume expansion. The finding of this work provides a new strategy for high-performance anode design by structural dimensionality manipulation and cycling-driven morphology reconstruction.

High-Performance Aqueous Zinc-Ion Batteries Based on Multidimensional V2 O3 Nanosheets@Single-Walled Carbon Nanohorns@Reduced Graphene Oxide Composite and Optimized Electrolyte.

The drawbacks of poor electronic conductivity and structural instability during the cycling process limit the electrochemical property of vanadium-based cathode materials for aqueous zinc-ion batteries. In addition, continuous growth and accumulation of zinc dendrites can puncture the separator and cause an internal short circuit in the battery. In this work, a unique multidimensional nanocomposite is designed by a facile freeze-drying method with subsequent calcination, consisting of V2 O3 nanosheets and single-walled carbon nanohorns (SWCNHs) crosslinked together and wrapped by reduced graphene oxide (rGO). The multidimensional structure can largely enhance the structural stability and electronic conductivity of the electrode material. Besides, additive Na2 SO4 in the ZnSO4 aqueous electrolyte not only prevents the dissolution of cathode materials but also suppresses the Zn dendrite growth. After considering the influence of additive concentration on ionic conductivity and electrostatic force for electrolyte, V2 O3 @SWCNHs@rGO electrode delivers a high initial discharge capacity of 422 mAh g-1 at 0.2 A g-1 and a high discharge capacity of 283 mAh g-1 after 1000 cycles at 5 A g-1 in 2 m ZnSO4 + 2 m Na2 SO4 electrolyte. Experimental techniques reveal that the electrochemical reaction mechanism can be expressed as the reversible phase transformation between V2 O5 and V2 O3 with Zn3 (VO4 )2 .

Polyanion-Type Na3 V2 (PO4 )2 F3 @rGO with High-Voltage and Ultralong-Life for Aqueous Zinc Ion Batteries.

Aqueous zinc ion batteries (AZIBs) have attracted much interest in the next generation of energy storage devices because of their elevated safety and inexpensive price. Polyanionic materials have been considered as underlying cathodes owing to the high voltage, large ionic channels and fast ionic kinetics. However, the low electronic conductivity limits their cycling stability and rate performance. Herein, mesoporous Na3 V2 (PO4 )2 F3 (N3VPF) nanocuboids with the size of 80-220 nm cladded by reduced graphene oxide (rGO) have been successfully prepared to form 3D composite (N3VPF@rGO) by a novel and fast microwave hydrothermal with subsequent calcination strategy. The enhanced conductivity, strengthened pseudocapacitive behaviors, enlarged DZn 2+ , and stable structure guarantee N3VPF@rGO with splendid Zn2+ storage performance, such as high capacity of 126.9 mAh g-1 at 0.5 C (1 C = 128 mA g-1 ), high redox potentials at 1.48/1.57 V, high rate capacity of 93.9 mAh g-1 at 20 C (short charging time of 3 mins) and extreme cycling stability with capacity decay of 0.0074% per cycle after 5000 cycles at 15 C. The soft package batteries also present preeminent performance, demonstrating the practical application values. In situ X-ray diffraction, ex situ transmission electron microscopy and X-ray photoelectron spectroscopy reveal a reversible Zn2+ insertion/extraction mechanism.

VO2·0.26H2O nanobelts@reduced graphene oxides as cathode materials for high-performance aqueous zinc ion batteries.

A simple microwave-assisted hydrothermal approach is adopted to synthesize VO2·0.26H2O nanobelts@reduced graphene oxide (VO2·0.26H2O@rGO), which is regarded as a promising cathode material for ZIBs. Compared to VO2·0.26H2O, VO2·0.26H2O@rGO has a large specific surface area and low charge transfer resistance, improving its electrochemical properties. The large lattice spacing, high capacitive Zn2+ storage behavior, fast Zn2+ transfer rate and stable structure are also responsible for the performance.

In-situ fabrication of active interfaces towards FeSe as advanced performance anode for sodium-ion batteries.

Transition metal selenides have gained enormous interest as anodes for sodium ion batteries (SIBs). Nonetheless, their large volume expansion causing poor rate and inferior cycle stability during Na+ insertion/extraction process hinders their further applications in SIBs. Herein, a confined-regulated interfacial engineering strategy towards the synthesis of FeSe microparticles coated by ultrathin nitrogen-doped carbon (NC) is demonstrated (FeSe@NC). The strong interfacial interaction between FeSeand NC endows FeSe@NC with fast electron/Na+ transport kinetics and outstanding structural stability, delivering unexceptionable rate capability (364 mAh/gat 10 A/g) and preeminent cycling durability (capacity retention of 100 % at 1 A/g over 1000 cycles). Furthermore, variousex situcharacterization techniques and density functional theory (DFT) calculations have been applied to demonstrate the Na+ storage mechanism of FeSe@NC. The assembled Na3V2(PO4)2F3@rGO//FeSe@NC full cell also displays a high capacity of 241 mAh/gat 1 A/g with the capacity retention of nearly 100 % over 2000 cycles, and delivers a supreme energy density of 135 Wh kg-1 and a topmost power density of 495 W kg-1, manifesting the latent applications of FeSe@NC in the fast charging SIBs.

"Carbon quantum dots-glue" enabled high-capacitance and highly stable nickel sulphide nanosheet electrode for supercapacitors.

A facile "carbon quantum dots glue" strategy for the fabrication of honeycomb-like carbon quantum dots/nickel sulphide network arrays on Ni foam surface is successfully demonstrated. This design realizes the immobilization of nanosheet arrays and maintains a strong adhesion to the collector, forming a three-dimensional (3D) honeycomb-like architecture. Thanks to the unique structural advantages, the resulting bind-free electrode with high active mass loading of 6.16 mg cm-2 still exhibits a superior specific capacitance of 1130F g-1 at 2 A g-1, and maintains 80% of the initial capacitance even at 10 A g-1 after 3000 cycles. Furthermore, the assembled asymmetrical supercapacitor delivers an energy density of 18.8 Wh kg-1 at a power density of 134 W kg-1, and outstanding cycling stability (100% of initial capacitance retention after 5000 cycles at 5 mA cm-2). These impressive results indicate a new perspective to design various binder-free electrodes for electrochemical energy storage devices.

Robust Strategy of Quasi-Solid-State Electrolytes to Boost the Stability and Compatibility of Mg Ion Batteries.

Magnesium ion batteries (MIBs) have attracted a lot of attention because of the natural abundance of magnesium, high volumetric energy density, and superior safety. Nevertheless, MIBs are still in their infancy because of the significant challenge in developing a suitable electrolyte with low flammability, high ionic conductivity, and compatibility with the Mg anode. Herein, we construct rechargeable quasi-solid-state MIBs based on tailored polymer electrolytes. The quasi-solid state electrolyte of poly(vinylidene fluoride-co-hexafluoropropylene)-nanosized SiO2-Mg(TFSI)2 combines the outstanding dynamic property of a liquid electrolyte and the good stability of a solid-state electrolyte. It exhibits a highly reversible Mg2+ deposition-dissolution capability, high ion conductivity (0.83 mS cm-1), and superior compatibility with the Mg metal and cathode. The quasi-solid-state MIBs with a layered titanic oxide cathode show a high reversible capacity of 129 mA h g-1 at 50 mA g-1 (150 W h kg-1) without any decay after 100 cycles.

Rechargeable Na-CO2 Batteries Starting from Cathode of Na2CO3 and Carbon Nanotubes.

Na-CO2 batteries have attracted significant attentions due to their high energy density and effective utilization of greenhouse gas CO2. However, all reported Na-CO2 batteries employ excessive preloaded metal Na, which will lead to safety issues such as dendrite formation and short circuit. In addition, the charging mechanism of reported Na-CO2 batteries is not very clear. Here we report the Na-CO2 batteries, starting from the cathode of cheap Na2CO3 and multiwalled carbon nanotubes (CNTs). Due to the effective electron transfer and high reactivity, the decomposition of Na2CO3 and CNTs could take place under 3.8 V. The charging mechanism of 2Na2CO3 + C → 4Na + 3CO2 without any side reactions is revealed by in/ex situ techniques such as Raman, gas chromatograph, and optical microscope. Dendrite-free Na can quantitatively deposit on the Super P/Al anode because of large specific surface area and low nucleation barrier of the anode for Na plating. The batteries could deliver an energy density of 183 Wh kg-1 (based on the whole mass of the pouch-type batteries, 4 g) with stable cycling performance. This work reveals that safe rechargeable Na-CO2 batteries could be constructed by cheap Na2CO3 and multiwalled carbon nanotubes.

MnOOH nanorods as high-performance anodes for sodium ion batteries.

MnOOH nanorods, which were prepared using a hydrothermal method, have been used for the first time as anode materials for sodium ion batteries. The as-prepared MnOOH nanorods with lengths of 1.2-3.7 µm and diameters of 60-90 nm delivered high performance of reversible electrochemical Na/Na+ storage such as an initial discharge capacity of 485.5 mA h g-1 at 80 mA g-1, a high initial Coulombic efficiency of 86.7% and a low average potential polarization of 0.36 V. Instrumental analyses with ex situ XRD, TEM and XPS show that the sodium storage mechanism in MnOOH can be related to the reversible formation of MnO and NaOH. This work demonstrates that cheap MnOOH nanorods are potential anode materials for SIBs.

Comparison of LiVPO4F to Li4Ti5O12 as anode materials for lithium-ion batteries.

In this paper, we reported on a comparison of LiVPO4F to Li4Ti5O12 as anode materials for lithium-ion batteries. Combined with powder X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, galvanostatic discharge/charge tests and in situ X-ray diffraction technologies, we explore and compare the insertion/extraction mechanisms of LiVPO4F based on the V3+/V2+/V+ redox couples and Li4Ti5O12 based on the Ti4+/Ti3+ redox couple cycled in 1.0-3.0 V and 0.0-3.0 V. The electrochemical results indicate that both LiVPO4F and Li4Ti5O12 are solid electrolyte interphase free materials in 1.0-3.0 V. The insertion/extraction mechanisms of LiVPO4F and Li4Ti5O12 are similar with each other in 1.0-3.0 V as proved by in situ X-ray diffraction. It also demonstrates that both samples possess stable structure in 0.0-3.0 V. Additionally, the electrochemical performance tests of LiVPO4F and Li4Ti5O12 indicate that both samples cycled in 0.0-3.0 V exhibit much higher capacities than those cycled in 1.0-3.0 V but display worse cycle performance. The rate performance of Li4Ti5O12 far exceeds that of LiVPO4F in the same electrochemical potential window. In particular, the capacity retention of Li4Ti5O12 cycled in 1.0-3.0 V is as high as 98.2% after 20 cycles. By contrast, Li4Ti5O12 is expected to be a candidate anode material considering its high working potential, structural zero-strain property, and excellent cycle stability and rate performance.