Template-free fabrication of 1D core-shell MoO2@MoS2/nitrogen-doped carbon nanorods for enhanced lithium/sodium-ion storage

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%.

Recent progress in MoS2 nanostructures for biomedical applications: Experimental and computational approach

In the category of 2D materials, MoS2 a transition metal dichalcogenide, is a novel and intriguing class of materials with interesting physicochemical properties, explored in applications ranging from cutting-edge optoelectronic to the frontiers of biomedical and biotechnology. MoS2 nanostructures an alternative to heavy toxic metals exhibit biocompatibility, low toxicity and high stability, and high binding affinity to biomolecules. MoS2 nanostructures provide a lot of opportunities for the advancement of novel biosensing, nanodrug delivery system, electrochemical detection, bioimaging, and photothermal therapy. Much efforts have been made in recent years to improve their physiochemical properties by developing a better synthesis approach, surface functionalization, and biocompatibility for their safe use in the advancement of biomedical applications. The understanding of parameters involved during the development of nanostructures for their safe utilization in biomedical applications has been discussed. Computational studies are included in this article to understand better the properties of MoS2 and the mechanism involved in their interaction with biomolecules. As a result, we anticipate that this combined experimental and computational studies of MoS2 will inspire the development of nanostructures with smart drug delivery systems, and add value to the understanding of two-dimensional smart nano-carriers.

Carbonized Polymer Dots for Controlling Construction of MoS2 Flower-Like Nanospheres to Achieve High-Performance Li/Na Storage Devices

Despite being one of the most promising materials in anode materials, molybdenum sulfide (MoS2 ) encounters certain obstacles, such as inadequate cycle stability, low conductivity, and unsatisfactory charge-discharge (CD) rate performance. In this study, a novel approach is employed to address the drawbacks of MoS2 . Carbon polymer dots (CPDs) are incorporated to prepare three-dimensional (3D) nanoflower-like spheres of MoS2 @CPDs through the self-assembly of MoS2 2D nanosheets, followed by annealing at 700 °C. The CPDs play a main role in the creation of the nanoflower-like spheres and also mitigate the MoS2 nanosheet limitations. The nanoflower-like spheres minimize volume changes during cycling and improve the rate performance, leading to exceptional rate performance and cycling stability in both Lithium-ion and Sodium-ion batteries (LIBs and SIBs). The optimized MoS2 @CPDs-2 electrode achieves a superb capacity of 583.4 mA h g-1 at high current density (5 A g-1 ) after 1000 cycles in LIBs, and the capacity remaining of 302.8 mA h g-1 after 500 cycles at 5 A g-1 in SIBs. Additionally, the full cell of LIBs/SIBs exhibits high capacity and good cycling stability, demonstrating its potential for practical application in fast-charging and high-energy storage.

Bonding iron chalcogenides in a hierarchical structure for high-stability sodium storage

Owing to price-boom and low-reserve of Lithium ion batteries (LIBs), cost-cutting and well-stocked sodium ion batteries (SIBs) attract a lot of attention, aiming to develop an effective energy storage and conversion equipment. As a typical anode for SIBs, Iron sulfide (FeS) is difficult to maintain the high theoretical capacity. Structural instability and inherent low conductivity limit the cyclic and rate performance of FeS. Herein, hierarchical architecture of FeS-FeSe₂ coated with nitrogen-doped carbon (NC) is obtained by single-step solvothermal method and two-stage high-temperature treatments. Specifically, lattice imperfections provided by heterogeneous interfaces increase the Na⁺ storage sites and fasten ion/electron transfer. Synergistic effect induced by the hierarchical architecture effectively enhances the electrochemical activity and reduces the resistance, which contributes to the transfer kinetics of Na⁺. In addition, the phenomenon that heterogeneous interfaces provide more active site and extra migration Na⁺ path is also proved by density functional theory (DFT). As an anode for SIBs, FeS-FeSe₂/NC (FSSe/C) delivers highly reversible capacity (704.5 mAh·g^-1 after 120 cycles at 0.2 A·g^-1), excellent rate performance (326.3 mAh·g^-1 at 12 A·g^-1) and long-lasting durability (492.3 mAh·g^-1 after 1000 cycles at 4 A·g^-1 with 100 % capacity retention). Notably, the full battery, assembled with FSSe/C and Na₃V₂(PO₄)₃/C (NVP/C), delivers reversible capacity of 252.1 mAh·g^-1 after 300 cycles at 1 A·g^-1. This work provides a facile method to construct a hierarchical architecture anode for high-performance SIBs.

CoS2 Nanoparticles Anchored on MoS2 Nanorods As a Superior Bifunctional Electrocatalyst Boosting Li2 O2 Heteroepitaxial Growth for Rechargeable Li-O2 Batteries

Developing an excellent bifunctional catalyst is essential for the commercial application of Li-O₂ batteries. Heterostructures exhibit great application potential in the field of energy catalysis because of the accelerated charge transfer and increased active sites on their surfaces. In this work, CoS₂ nanoparticles decorated on MoS₂ nanorods are constructed and act as a superior cathode catalyst for Li-O₂ batteries. Coupling MoS₂ and CoS₂ can not only synergistically enhance their electrical conductivity and electrochemical activity, but also promote the heteroepitaxial growth of discharge products on the heterojunction interfaces, thus delivering high discharge capacity, stable cycle performance, and good rate capability.

Binary-Metal Mn2SnO4 Nanoparticles and Sn Confined in a Cubic Frame with N-Doped Carbon for Enhanced Lithium and Sodium Storage

Sn-based materials have been popularly researched as anodes for energy storage due to their high theoretical capacity. However, the sluggish reaction kinetics and unsatisfied cycling stability caused by poor conductivity and dramatic volume expansion are still pivotal barriers for the development of Sn-based materials as anodes. In this work, the binary-metal Mn₂SnO₄ nanoparticles and Sn encapsulated in N-doped carbon (Sn@Mn₂SnO₄-NC) were fabricated by multistep reactions and employed as the anode for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). The coexistence of binary metals (Sn and Mn) can improve intrinsic conductivity. Simultaneously, hollow architecture along with carbon relieves internal stress and prevents structural collapse. A Sn@Mn₂SnO₄-NC anode delivers an appealing capacity of 1039.5 mAh g^-1 for 100 cycles at 100 mA g^-1 and 823.8 mAh g^-1 for 600 cycles at 1000 mA g^-1 in LIBs. When evaluated as an anode in SIBs, the Sn@Mn₂SnO₄-NC anode tolerates up to 7000 cycles at 2000 mA g^-1 and maintains a capacity of 185.8 mAh g^-1. Quantified kinetic investigations demonstrate the high contribution of pseudocapacitive effects during the cycle process. Furthermore, density functional theory (DFT) calculations further verify that introduction of the second metal (Mn) improves the conductivity of the material, which is favorable for charge transport. This work is expected to provide a feasible preparation strategy for binary-metal materials to enhance the performance of lithium- and sodium-ion batteries.

Self-assembly of carbon nanotubes on a hollow carbon polyhedron to enhance the potassium storage cycling stability of metal organic framework-derived metallic selenide anodes

Potassium-ion batteries (PIBs) is increasingly studied because of their suitable redox potential and high natural abundance. However, potential anode materials with long-term cycling stability are still in high demand because of the large radius of K⁺. Herein, an MOF-derived hierarchical carbon structure and the self-assembly of CNTs on hollow carbon polyhedrons are used as carbon matrices to disperse and stabilize metal selenides(Co-Se@CNNCP). When the hybrid is utilized in PIBs, it displays a specific capacity of 410 mA h g^-1 at 0.1 A g^-1 after 80 cycles and 253 mA h g^-1 at 0.5 A g^-1 after 200 cycles with a capacity retention of 100%, while the metal selenides dispersed on hollow carbon polyhedrons without CNTs (Zn-Co-Se@NCP) lose 86% of their capacity after 200 cycles. The superior cycling stability of the hybrid is mainly attributed to the large amounts of CNTs suppressing the agglomeration of the metal selenide nanoparticles on the surface, and the hollow carbon polyhedrons cause a high structural integrity during the repreated K⁺ insertion and extraction process. This work offers a feasible route to design a hierarchical carbon matrix for use as the anode materials of PIBs with long-term cycling stability.