Mo2C-Co heterostructure with carbon nanosheets decorated carbon microtubules: Different means for high-performance lithium-sulfur batteries

The practical applications of lithium sulfur batteries (LSBs) are hindered by notorious shuttle effect and sluggish conversion kinetics of intermediate polysulfides. Herein, Mo2C-Co heterogeneous particles decorated two-dimensional (2D) carbon nanosheets grown on hollow carbon microtubes (CCC@MCC) are synthesized. Three-dimensional (3D) carbon framework with Mo2C-Co heterogeneous particles combines the conductivity, adsorption and catalysis, effectively trapping and accelerating the conversion of polysulfides. As evidenced experimentally, the hetero-structured Mo2C-Co with high Li+ diffusion coefficient enables uniform precipitation and complete oxidation of Li2S. Meanwhile, CCC@MCC is found to have multiple application possibilities for lithium-sulfur batteries. As an interlayer, the cells deliver an excellent capacity of 881.1 mAh/g at 2C and still retain 438.2 mAh/g after 500 cycles under the low temperature of 0 ℃. As a sulfur carrier, the cell with a sulfur loading of 7.0 mg cm-2 exhibits a high area capacity of 5.3 mAh cm-2. This work provides an effective strategy to prepare heterostructured material and imaginatively exploit the application potential of it.

Size Effect for Inhibiting Polysulfides Shuttle in Lithium-Sulfur Batteries

It is undeniable that the dissolution of polysulfides is beneficial in speeding up the conversion rate of sulfur in electrochemical reactions. But it also brings the bothersome "shuttle effect". Therefore, if polysulfides can be retained on the cathode side, the efficient utilization of the polysulfides can be guaranteed to achieve the excellent performance of lithium-sulfur batteries. Based on this idea, considerable methods have been developed to inhibit the shuttling of polysulfides. It is necessary to emphasize that no matter which method is used, the solvation mechanism, and existence forms of polysulfides are essential to analyze. Especially, it is important to clarify the sizes of different forms of polysulfides when using the size effect to inhibit the shuttling of polysulfides. In this review, a comprehensive summary and in-depth discussion of the solvation mechanism, the existing forms of polysulfides, and the influencing factors affecting polysulfides species are presented. Meanwhile, the size of diverse polysulfide species is sorted out for the first time. Depending on the size of polysulfides, tactics of using size effect in cathode, separator, and interlayer parts are elaborated. Finally, a design idea of materials pore size is proposed to satisfy the use of size effect to inhibit polysulfides shuttle.

The Integration of Biopolymer-Based Materials for Energy Storage Applications: A Review

Biopolymers are an emerging class of novel materials with diverse applications and properties such as superior sustainability and tunability. Here, applications of biopolymers are described in the context of energy storage devices, namely lithium-based batteries, zinc-based batteries, and capacitors. Current demand for energy storage technologies calls for improved energy density, preserved performance overtime, and more sustainable end-of-life behavior. Lithium-based and zinc-based batteries often face anode corrosion from processes such as dendrite formation. Capacitors typically struggle with achieving functional energy density caused by an inability to efficiently charge and discharge. Both classes of energy storage need to be packaged with sustainable materials due to their potential leakages of toxic metals. In this review paper, recent progress in energy applications is described for biocompatible polymers such as silk, keratin, collagen, chitosan, cellulose, and agarose. Fabrication techniques are described for various components of the battery/capacitors including the electrode, electrolyte, and separators with biopolymers. Of these methods, incorporating the porosity found within various biopolymers is commonly used to maximize ion transport in the electrolyte and prevent dendrite formations in lithium-based, zinc-based batteries, and capacitors. Overall, integrating biopolymers in energy storage solutions poses a promising alternative that can theoretically match traditional energy sources while eliminating harmful consequences to the environment.

Cerium-based nanoparticles triggered catalytic reaction for the colorimetric and ratiometric fluorimetric dual-signal sensing of vitamin C

The construction of multi-modal detection methods has attracted widespread attention in the field of biosensing due to their high sensitivity and strong anti-interference ability. In this manuscript, we developed colorimetric and ratiometric fluorescence dual-signal optical methods based on cerium-based nanoparticles (Ce NPs) for the sensitive detection of vitamin C (VC). The catalysis of Ce NPs with excellent peroxidase-like activity upon the reaction of H₂O₂ with OPD was occurred, promoting the oxidation of o-phenylenediamine (OPD) to generate 2,3-diaminophennazine (OPDox) with an obvious absorption peak at 420 nm and an emission peak at 565 nm. In the presence of VC, VC not only inhibited the generation of OPDox, but also induced the formation of quinoxaline with an obvious absorption peak at 336 nm and an emission peak at 430 nm. This can be visually observed and monitored by measuring the absorbance of peak at 336 nm (A₃₃₆) and the ratiometric fluorescence intensity (F₄₃₀/F₅₆₅). Therefore, the dual-signal methods are constructed for the detection of VC. The detection lower detection limits are 8.0 μM and 8.4 μM when using the fluorescence and colorimetric signals, respectively. Furthermore, the proposed methods are successfully applied to the detection of VC in practical samples with satisfactory results.

Advanced cathodic free-standing interlayers for lithium-sulfur batteries: understanding, fabrication, and modification

In the past decades, lithium-sulfur batteries (LSBs) have demonstrated huge practical potential due to their ultrahigh theoretical specific capacity, low price, and environmental friendliness. However, LSBs are still faced with the problems of volumetric expansion, slow reaction kinetics, and short working life due to the shuttling of polysulfides. The introduction of a free-standing interlayer is a good way to solve the problems because of the physical confinement, chemical entrapment, and conversion. This review summarizes the common fabrication methods of free-standing interlayers, including the power-originated and film-originated methods. The modification of the as-prepared free-standing interlayers is also accomplished into physical treatment, atomic doping, and compound introduction. Finally, we conclude and compare the different fabrication methods of free-standing interlayers and their modifications and put forward the outlook of the high-performance free-standing interlayers.

An integrated flexible film as cathode for High-Performance Lithium-Sulfur battery

Poor cycling stability and low volumetric capacity of sulfur cathode prevents practical application of Lithium-sulfur (Li-S) batteries. Herein, we demonstrate a strategy to address the two drawbacks of sulfur cathode by synthesizing a compact and flexible film cathode with bilayer structure using a two-step vacuum filtration method. Two layers make up the sulfur cathode, active layer (sulfur-acethlene black (SC) spheres) and barrier layer (three dimensional MnO₂-graphene oxide-multi-walled carbon nanotubes (MnO₂-GO-CNTs) composites), which are integrated together by reduced graphene oxide (rGO) through self-binding. The rGO sheets provide an electrical conductive framework and a stable architecture to accommodate volume changes of sulfur. SC spheres stacked orderly between the rGO layers facilitate fast Li⁺ storage and energy release. Polar MnO₂-GO-CNTs composites with large specific surface area have not only afforded efficient sites for chemically binding polysulfides, but also provided fast electron transfer for accelerating polysulfides redox reaction. Consequently, the integrated film cathode exhibits an unprecedented cycling stability of ~0.0279% capacity decay per cycle over more than 600 cycles at 1C and high volumetric capacity of 1021.9 Ah L^-1 at 2C. Meanwhile, a foldable Li-S battery based on this flexible cathode is fabricated and shows excellent mechanical and electrochemical properties. The integrated flexible sulfur cathode of this study sheds light on the design strategies for application in flexible high volumetric capacity system.

Limiting sulfur and mastering the diffusion of lithium ions with cerium oxide-based porous carbon rods

Cerium dioxide nanocrystals embedded in porous carbon rod materials were used for sulfur storage and embedding. Polar cerium dioxide effectively adsorbed polysulfide and inhibited the shuttle effect. By calculating the diffusion coefficient of the lithium-ions, it was concluded that the porous carbon rod material with cerium oxide was beneficial for the rapid binding of lithium ions and sulfur.

Integrated Design of Interlayer/Current-Collector: Heteronanowires Decorated Carbon Microtube Fabric for High-Loading and Lean-Electrolyte Lithium-Sulfur Batteries

Low sulfur loading, high electrolyte/sulfur (E/S) ratio, and sluggish sulfur redox reaction are the main challenges that severely impede the practical application of lithium-sulfur batteries (LSBs). To address these problems, a self-standing hollow carbonized cotton cloth (CCC) decorated with TiO₂ -TiN heteronanowires (CCC@TiO₂ -TiN) is proposed to replace the traditional cathode. Concretely, one side of CCC@TiO₂ -TiN serves as a current-collector to load sulfur (CCC@TiO₂ -TiN/S), while the other side facing the separator acts as interlayer to inhibit shuttle effect. This advanced intergrated interlayer/current-collector cathode is endowed with excellent 3D electron/ion transportation, a strong confinement barrier, and vast sulfur loading sites. Moreover, the as-developed TiO₂ -TiN heteronanowires work as in situ capture and catalysis sites for the reversible and accelerated sulfur redox reaction. Therefore, the intergrated cathode of CCC@TiO₂ -TiN/S achieves an ultrahigh sulfur loading of 13 mg cm^-2 and delivers a superb areal capacity of 9.09 mAh cm^-2 under the ultralow E/S ratio of 4.6 µL mg^-1 . This work provides a new model material to achieve high sulfur loading and lean-electrolyte toward the practical LSBs with high specific energy density.

Designing conductive networks of hybrid carbon enables stable and long-lifespan cotton-fiber-based lithium–sulfur batteries

In modern society, flexible rechargeable batteries have become a burgeoning apodictic choice for wearable devices. Conventional lithium–sulfur batteries lack sufficient flexibility because their electrode materials are too rigid to bend. Along with the inherent high theoretical capacity of sulfur, lithium–sulfur batteries have some issues, such as dissolution and shuttle effect of polysulfides, which restricts their efficiency and practicability. Here, a flexible and “dead-weight”-free lithium–sulfur battery substrate with a three-dimensional structure was prepared by a simple strategy. With the cooperative assistance of carbon nanotubes and graphene attached to cotton fibers, the lithium–sulfur battery with 2.0 mg cm⁻² sulfur provided a high initial discharge capacity of 1098.7 mA h g⁻¹ at 1C, and the decay rate after 300 cycles was only 0.046% per cycle. The initial discharge capacity at 2C was 872.4 mA h g⁻¹ and the capacity was maintained 734.4 mA h g⁻¹ after 200 cycles with only a 0.079% per cycle decay rate.

A flexible, “dead weight”-free lithium–sulfur battery substrate was prepared, and batteries using these substrates showed great electrochemical performance.

Non-tubular-biomass-derived nitrogen-doped carbon microtubes for ultrahigh-area-capacity lithium-ion batteries

The ever-increasing electric vehicles and portable electronics make lithium-ion barreries (LIBs) toward high energy density, resulting in long driving range and standby times. Generally, excellent electrochemical performance can be obtained in thin electrode materials with low mass loadings (<1 mg cm^-2), but it is difficult to be achieved in commercial electrodes with high mass loadings (>10 mg cm^-2). In this work, we report a facile method for fabricating nitrogen doped carbon microtubes (N-CMTs) consisted of crumped carbon nanosheets for high-performance LIBs with ultrahigh mass loading, where non-tubular biomass waste (i.e., peanut dregs) is employed as the precursor. Benefiting from the hollow tubular conductive network, high graphitization, and hierarchical structure, the as-synthesized N-CMTs exhibit ultrahigh area capacity of 6.27 mAh cm^-2 at a current density of 1.5 mA cm^-2 with a high mass loading of 15 mg cm^-2 and superior cycling stability for LIBs. Our approach provides an effective strategy for the preparation of nitrogen-doped carbon microtubes to develope high energy LIBs with high mass loading electrodes.

Carbon Microtube Textile with MoS2 Nanosheets Grown on Both Outer and Inner Walls as Multifunctional Interlayer for Lithium-Sulfur Batteries

The shuttle effect of soluble lithium polysulfides during the charge/discharge process is the key bottleneck hindering the practical application of lithium-sulfur batteries. Herein, a multifunctional interlayer is developed by growing metallic molybdenum disulfide nanosheets on both outer and inner walls of cotton cloth derived carbon microtube textile (MoS2@CMT). The hollow structure of CMT provides channels to favor electrolyte penetration, Li+ diffusion and restrains polysulfides via physical confinement. The hydrophilic and conductive 1T-MoS2 nanosheets facilitate chemisorption and kinetic behavior of polysulfides. The synergic effect of 1T-MoS2 nanosheets and CMT affords the MoS2@CMT interlayer with an efficient trapping-diffusion-conversion ability toward polysulfides. Therefore, the cell with the MoS2@CMT interlayer exhibits enhanced cycling life (765 mAh g-1 after 500 cycles at 0.5 C) and rate performance (974 mAh g-1 at 2 C and 740 mAh g-1 at 5 C). This study presents a pathway to develop low-cost multifunctional interlayers for advanced lithium-sulfur batteries.

Facile synthesis of porous Co3O4 nanoflakes as an interlayer for high performance lithium-sulfur batteries

The "shuttle effect" of long-chain polysulfides and the low conductivity of elemental sulfur lead to the inferior cycling stability of lithium-sulfur batteries and imped their practical applications. Herein, Co₃O₄ nanoflakes with uniform macro pores distribution were synthesized via facile oil bath and calcination methods. Coupled with super P and coated on common polypropylene separators, they were expected to hinder the migration of lithium polysulfides (LiPSs) and accelerate the redox kinetics of polysulfides. Coin cells assembled with the Co₃O₄-super P interlayer exhibited a capacity of 760 mA h g^-1 at 1 C, maintained 598 mA h g^-1 after 350 cycles, and the decay rate of discharge capacity was only about 0.062% per cycle. Such high performance can be attributed to the synergistic effects between polar Co₃O₄ and conductive super P. The facile fabrication method and high performance make the Co₃O₄-super P interlayer a feasible material to apply in lithium-sulfur batteries.

Implanting Atomic Cobalt within Mesoporous Carbon toward Highly Stable Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries hold great promise to serve as next-generation energy storage devices. However, the practical performances of Li-S batteries are severely limited by the sulfur cathode regarding its low conductivity, huge volume change, and the polysulfide shuttle effect. The first two issues have been well addressed by introducing mesoporous carbon hosts to the sulfur cathode. Unfortunately, the nonpolar nature of carbon materials renders poor affinity to polar polysulfides, leaving the shuttling issue unaddressed. In this contribution, atomic cobalt is implanted within the skeleton of mesoporous carbon via a supramolecular self-templating strategy, which simultaneously improves the interaction with polysulfides and maintains the mesoporous structure. Moreover, the atomic cobalt dopants serve as active sites to improve the kinetics of the sulfur redox reactions. With the atomic-cobalt-decorated mesoporous carbon host, a high capacity of 1130 mAh g_S ^-1 at 0.5 C and a high stability with a retention of 74.1% after 300 cycles are realized. Implanting atomic metal in mesoporous carbon demonstrates a feasible strategy to endow nanomaterials with targeted functions for Li-S batteries and broad applications.

A review of biomass materials for advanced lithium-sulfur batteries

This review summarizes recent progress of biomass-derived materials in Li–S batteries. These materials are promising due to their advantages including strong physical and chemical adsorption, high abundance, low cost, and environmental friendliness.

High energy density and low cost make lithium–sulfur (Li–S) batteries famous in the field of energy storage systems. However, the advancement of Li–S batteries is evidently hindered by the notorious shuttle effect and other issues that occur in sulfur cathodes during cycles. Among various strategies applied in Li–S batteries, using biomass-derived materials is more promising due to their outstanding advantages including strong physical and chemical adsorptions as well as abundant sources, low cost, and environmental friendliness. This review summarizes the recent progress of biomass-derived materials in Li–S batteries. By focusing on the aspects of carbon hosts, separator materials, bio-polymer binders, and all-solid-state electrolytes, the authors aim to shed light on the rational design and utilization of biomass-derived materials in Li–S batteries with high energy density and long cycle lifespan. Perspectives regarding future research opportunities in biomass-derived materials for Li–S batteries are also discussed.

Nitrogen, sulfur-codoped micro–mesoporous carbon derived from boat-fruited sterculia seed for robust lithium–sulfur batteries

The diverse textures and tunable surface properties of abundant bioresources offer great opportunities to utilize biochar materials as sulfur hosts for naturally boosting the electrochemical performances of Li–S batteries. Herein, a N, S-codoped micro–mesoporous carbon was synthesized from boat-fruited sterculia seed, and used as a sulfur host matrix for Li–S batteries. After sulfur infiltration (≈62% sulfur) and cell assembly, the obtained S/NSBC cathode shows outstanding discharge–charge performance, good rate capability, and especially long cycling stability. A high initial discharge capacity of 1478 mA h g⁻¹ was achieved at 0.1C, and the reversible discharge capacity was still retained at 649 mA h g⁻¹ after 500 cycles at 0.5C with ultralow decay rate of 0.08% per cycle, and especially zero-capacity-decay after 300 cycles. Such superior electrochemical performance of S/NSBC cathode is attributed to the synergy of the unique 3D conductive micro–mesoporous frameworks and huge N, S-codoped polar surface within the carbon matrix, which can physically confine the dissolved polysulfides within the pore structures, and chemically anchor the polysulfides through chemical interaction between lithium polysulfides and N and S sites, thus enabling the favorable reaction kinetics, efficient utilization of sulfur, and effective mitigation of polysulfide diffusion and shuttling within the cathode. This work well manifests the great feasibility and superiority of utilizing bioresources for high performance Li–S batteries.

Physical confinement and chemical adsorption of polysulfides on boat-fruited sterculia seed derived nitrogen, sulfur-codoped micro–mesoporous carbon for robust lithium–sulfur batteries.

Waste spunlaced facial puff derived monolithic flexible carbon framework (WCF): an ultralow-cost, recyclable and eco-friendly sorbent for oils and organic solvents

Due to the spunlaced effect, waste spunlaced facial puff has a high degree of fiber entanglement and an abundant three-dimensional (3D) network porous structure, which make it form a 3D carbon framework material more easily after carbonization. For the first time, the monolithic 3D carbon framework is synthesized from waste spunlaced facial puff (WCF) and used as the adsorbent for contaminants in water. The adsorption capacity of WCF for oils and organic reagents can be 34–137 times its own weight. Over five adsorption-harvesting cycles, the adsorption capacity of WCF to organic pollutants can recover up to 95% of its initial capacity. Moreover, WCF exhibits stable permeation flux and high separation efficiency in a water–heavy oil system, which is about 7714 L m⁻² h⁻¹ and higher than 99%, respectively. With a combination of waste spunlaced facial puff with monolithic 3D porous structure as a raw material, facile and green preparation process, low density, excellent hydrophobicity and lipophilicity, WCF as an adsorbent has great superiority in removal of organic pollutant solvents and environmental protection as well as other applications, such as energy storage materials, catalyst carriers, electric information, etc. Furthermore, this work would provide a new strategy for recovery use of waste spunlaced cotton materials.

A three-dimensional carbon framework material as an excellent sorbent for oils and organic solvents was synthesized using waste spunlaced facial puff.