Dual effects of the carbon fibers/Ti3C2Tx interlayer on retarding shuttle of polysulfides for stable Lithium-Sulfur batteries

A Review of Electrospun Carbon-Based Nanofibers Materials used in Lithium-Sulfur Batteries

Commercial lithium-ion batteries are gradually approaching their theoretical specific energy, which cannot meet the fast-growing energy storage demands. Lithium-sulfur (Li-S) batteries are anticipated to supersede lithium-ion batteries as the next-generation energy storage system owing to their high atheoretical specific capacity (1675 mAh g-1) and energy density (2600 Wh kg-1). Nonetheless, Li-S batteries encounter several challenges, including the inadequate conductivity of sulfur and lithium sulfide, sulfur's volume expansion, and the shuttle effect of lithium polysulfides, all of which significantly impact the practical utilization of Li-S batteries. Electrospun carbon-based nanofibers can simultaneously resolve these issues with their economical preparation, distinctive nanostructure, and exceptional flexibility. This review presents the most recent research findings on electrospun carbon-based nanofibers materials serving as sulfur hosts and interlayer components in Li-S batteries. We analyzed the impact of the material's structural design on the performance of Li-S batteries and the relative underlying mechanism. Finally, the current challenges and issues faced by carbon-based nanofibers composites in the application of Li-S batteries are summarized, and the future development trajectory are outlined.

Three-Dimensional MXenes for Supercapacitors: A Review

Supercapacitors have the characteristics of high power density and long cycle life, but the low energy density limits their further development. The 2D transitional metal carbides/nitrides (MXenes) show great application prospects in the field of supercapacitors due to their superior volumetric capacitance, metallic-like conductivity, tunable surface terminations, and structural advantages. However, like other 2D materials, MXenes suffer from the inevitable problem of nanosheet restacking and aggregation, which reduces the overall active surface sites and blocks the accessibility of the electrolyte ions. The transformation of 2D MXene nanosheets into 3D architectures is proven effective to overcome the restacking problem. The review briefly summarizes the preparation strategies of 3D MXene materials, including template-assisted method, framework-assisted method, chemical assembly method, foaming method, and other methods with the discussion centered on the performances of 3D MXenes in supercapacitors. Finally, an outlook on the current progress and opportunities is given to highlight the increasing popularity of 3D MXenes in supercapacitors.

Synergistic Capture and Conversion of Soluble Polysulfides in Li-S Batteries with Composite Freestanding Carbonaceous Interlayers

Lithium-sulfur (Li-S) batteries are considered promising next-generation energy storage systems due to their high energy density and low cost. However, their practical application still faces challenges such as the "shuttle effect" caused by polysulfides (LiPS). In this work, we use environmentally friendly bacterial cellulose (BC) as the substrate and prepare a flexible Ni-containing coordination polymer-modified carbonized BC interlayer (Ni-CBC). The combined electrochemical theoretical analysis shows that Ni-CBC not only captures LiPS effectively but also facilitates the electrochemical conversion of the adsorbed LiPS. As a result of these favorable features, the battery with the Ni-CBC interlayer delivers a stable discharge performance at 0.2C during long charge-discharge cycles and a high rate capacity of 852 mAh g^-1 at 2C. This work suggests that cellulose-based materials with tailored functionality can improve the performance of Li-S batteries.

V2CTX catalyzes polysulfide conversion to enhance the redox kinetics of Li-S batteries

Lithium-sulfur (Li-S) batteries have the potential to become the future energy storage system, yet they are plagued by sluggish redox kinetics. Therefore, enhancing the redox kinetics of polysulfides is key for the development of high-energy density and long-life Li-S batteries. Herein, a Ketjen Black (KB)/V₂CT_X modified separator (KB/V₂CT_X-PP) based on the catalytic effect in continuous solid-to-liquid-to-solid reactions is proposed to accelerate the conversion of sulfur species during the charge/discharge process in which the V₂CT_X can enhance the redox kinetics and inhibit polysulfide shuttling. The cells assembled with KB/V₂CT_X-PP achieve a gratifying first discharge capacity of 1236.1 mA h g^-1 at 0.2C and the average capacity decay per cycle reaches 0.049% within 1000 cycles at 1C. The work provides an efficient idea to accelerate redox conversion and suppress shuttle effects by designing a multifunctional catalytic separator.

Three-Dimensional Engineering of Sulfur/MnO2 Composites for High-Rate Lithium-Sulfur Batteries

Herein, a three-dimensional interconnected sulfur (3DIS) system is used to construct a cathode of the lithium-sulfur battery. Compared with the traditional methods of encapsulating sulfur, the 3DIS system serves as a framework to grow MnO₂, which ensures a high sulfur content of 91.5 wt % (the ratio of sulfur/host was 10.8) and a uniform distribution of sulfur. Due to the synergistic effect of the 3D interconnected architecture and the uniform coating layer of polar MnO₂, 3DIS@MnO₂ (3DISMO) delivers a capacity of 891 mA h g^-1 after 900 cycles at 1 C. Even at a rate of 10 C, a capacity decay rate of 0.061% per cycle is achieved.

Aluminum and lithium sulfur batteries: a review of recent progress and future directions

Advanced materials with various micro-/nanostructures have attracted plenty of attention for decades in energy storage devices such as rechargeable batteries (ion- or sulfur based batteries) and supercapacitors. To improve the electrochemical performance of batteries, it is uttermost important to develop advanced electrode materials. Moreover, the cathode material is also important that it restricts the efficiency and practical application of aluminum-ion batteries. Among the potential cathode materials, sulfur has become an important candidate material for aluminum-ion batteries cause of its considerable specific capacity. Two-dimensional materials are currently potential candidates as electrodes from lab-scale experiments to possible pragmatic theoretical studies. In this review, the fundamental principles, historical progress, latest developments, and major problems in Li-S and Al-S batteries are reviewed. Finally, future directions in terms of the experimental and theoretical applications have prospected.

Performance Study of MXene/Carbon Nanotube Composites for Current Collector- and Binder-Free Mg-S Batteries

The realization of sustainable and cheap Mg-S batteries depends on significant improvements in cycling stability. Building on the immense research on cathode optimization from Li-S batteries, for the first time a beneficial role of MXenes for Mg-S batteries is reported. Through a facile, low-temperature vacuum-filtration technique, several novel current collector- and binder-free cathode films were developed, with either dipenthamethylene thiuram tetrasulfide (PMTT) or S8 nanoparticles as the source of redox-active sulfur. The importance of combining MXene with a high surface area co-host material, such as carbon nanotubes, was demonstrated. A positive effect of MXenes on the average voltage and reduced self-discharge was also discovered. Ascribed to the rich polar surface chemistry of Ti3 C2 Tx MXene, an almost doubling of the discharge capacity (530 vs. 290 mA h g-1 ) was achieved by using MXene as a polysulfide-confining interlayer, obtaining a capacity retention of 83 % after 25 cycles.

Effect of Ti3C2Tx–PEDOT:PSS modified-separators on the electrochemical performance of Li–S batteries

Lithium–sulfur (Li–S) batteries have attracted much attention due to their high theoretical energy density, environmental friendliness, and low cost. However, the practical application of Li–S batteries is impeded by a severe shuttle effect. Using polar and conductive materials to prepare a modified separator as the second collector is an effective strategy to solve the shuttle effect. Herein, a Ti₃C₂T_x–PEDOT:PSS hybrid for modifying PP separators is successfully fabricated. In this hybrid, PEDOT:PSS can effectively prevent Ti₃C₂T_x nanosheets from restacking and enhance the electrical conductivity of Li–S batteries, thereby promoting fast Li⁺/electron transport and improving the sulfur utilization. Meanwhile, the introduction of Ti₃C₂T_x–PEDOT:PSS makes Ti₃C₂T_x nanosheets effectively anchor polysulfide, thus inhibiting the shuttle effect. As a result, Li–S cells with Ti₃C₂T_x–PEDOT:PSS modified-separators exhibit superior performances, including a high discharge capacity of 1241.4 mA h g⁻¹ at 0.2C, a long cycling stability, and a low decay rate of 0.030% per cycle at 0.5C for 1000 cycles.

Lithium–sulfur (Li–S) batteries have attracted much attention due to their high theoretical energy density, environmental friendliness, and low cost.

Sulfur encapsulated in a wafer-like carbon substrate with interconnected meso/micropores for high-performance lithium–sulfur batteries

A wafer-like graphene-based porous carbon substrate was synthesized for high-performance lithium–sulfur batteries.