Bifunctional K3PW12O40/Graphene Oxide-Modified Separator for Inhibiting Polysulfide Diffusion and Stabilizing Lithium Anode

Lithium-sulfur (Li-S) batteries are considered as promising candidates for next-generation batteries due to their high theoretical energy density. However, the practical application of Li-S batteries is still hindered by several challenges, such as the polysulfide shuttle and the growth of lithium dendrites. Herein, we introduce a bifunctional K3PW12O40/graphene oxide-modified polypropylene separator (KPW/GO/PP) as a highly effective solution for mitigating polysulfide diffusion and protecting the lithium anode in Li-S batteries. By incorporating KPW into a densely stacked nanostructured graphene oxide (GO) barrier membrane, we synergistically capture and rapidly convert lithium polysulfides (LiPSs) electrochemically, thus effectively suppressing the shuttling effect. Moreover, the KPW/GO/PP separator can stabilize the lithium metal anode during cycling, suppress dendrite formation, and ensure a smooth and dense lithium metal surface, owing to regulated Li+ flux and uniform Li nucleation. Consequently, the constructed KPW/GO/PP separator delivered a favorable initial specific capacity (1006 mAh g-1) and remarkable cycling performance at 1.0 C (626 mAh g-1 for up to 500 cycles with a decay rate of 0.075% per cycle).

Diffusional Features of a Lithium-Sulfur Battery Exploiting Highly Microporous Activated Carbon

Diffusion processes at the electrode/electrolyte interphase drives the performance of lithium-sulfur batteries, and activated carbon (AC) can remarkably vehicle ions and polysulfide species throughout the two-side liquid/solid region of the interphase. We reveal original findings such as the values of the diffusion coefficient at various states of charge of a Li-S battery using a highly porous AC, its notable dependence on the adopted techniques, and the correlation of the diffusion trend with the reaction mechanism. X-ray photoelectron spectroscopy (XPS) and X-ray energy dispersive spectroscopy (EDS) are used to identify in the carbon derived from bioresidues heteroatoms such as N, S, O and P, which can increase the polarity of the C framework. The transport properties are measured by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic intermittent titration technique (GITT). The study reveals Li⁺ -diffusion coefficient (D_Li ⁺ ) depending on the technique, and values correlated with the cell state of charge. EIS, CV, and GITT yield a D_Li ⁺ within 10^-7 -10^-8  cm²  s^-1 , 10^-8 -10^-9  cm²  s^-1 , and 10^-6 -10^-12  cm²  s^-1 , respectively, dropping down at the fully discharged state and increasing upon charge. GITT allows the evaluation of D_Li ⁺ during the process and evidences the formation of low-conducting media upon discharge. The sulfur composite delivers in a Li-cell a specific capacity ranging from 1300 mAh g^-1 at 0.1 C to 700 mAh g^-1 at 2C with a S loading of 2 mg cm^-2 , and from 1000 to 800 mAh g^-1 at 0.2C when the S loading is raised to 6 mg cm^-2 .

Composite capillary carbon tube Nb18W16O93as advanced anode material for aqueous ion capacitors

Niobium-tungsten bimetal oxides have received wide attention due to their excellent lattice properties. In this work, Nb₁₈W₁₆O₉₃(NbWO) with a tetragonal tungsten bronze structure was synthesized by simple hydrothermal method. NbWO was modified to provide high specific surface area via combining with hollow carbon nanotubes. Meanwhile, NbWO grows along the tube wall of carbon nanotubes, thus buffering the volume effect of NbWO particles. Also, the migration distance of Li-ion is effectively shortened, as well as the improved ion transfer efficiency and the reaction kinetics. In addition, carbon tube can enhance conductivity of NbWO, contributing to outstanding charge storage capacity and rate energy. Precisely, NbWO@C as electrode possesses large specific capacity (249.6 F g^-1at 0.5 A g^-1) and good rate performance (55.9% capacity retention from 0.5 to 2 A g^-1). The aqueous Li-ion capacitor presents the advantages of high safety, low cost and good environmental friendliness. An asymmetric aqueous capacitor AC//NbWO@C, based on 'water-in-salt' electrolyte with high concentration lithium acetate, exhibits a large energy density of 43.2 Wh kg^-1and a power density of 9 kW kg^-1. Generally, NbWO@C as anode materials shows superior application perspective.

A Hierarchically Porous ZIF@LDH Core-Shell Structure for High-Performance Supercapacitors

Designing nanocomposites with good electrochemical properties is one of the challenges in constructing supercapacitors. Adjustable metal-organic frameworks (MOFs) have potential research value in improving charge storage and transfer due to their multi-porosity. Moreover, MOFs can serve as a precursor to various derivatives. Herein, a series of core-shell structures with macro-microporous ZIF-67 (M-ZIF-67) as the core and layered double hydroxide (LDH) as the shell were synthesized based on polystyrene spheres (PSs) template via a simple ion etching method. As a result, the sample of M-ZIF-67@LDH4 shows a specific capacitance of 597.6 F g^-1 at 0.5 A g^-1 and a high rate retention of 92% at 3 A g^-1 .

Electrochemical energy storage electrodes from fruit biochar

This review investigates the electrochemical energy storage electrode (EESE) as the most important part of the electrochemical energy storage devices (EES) prepared from fruit-derived carbon. The EES devices include batteries, supercapacitors, and hybrid devices that have various regular and advanced applications. The preparation of EESE from fruit wastes not only reduce the price of the electrode but also lead to enhance the electrochemical properties of the electrode. The astonishing results of fruits biochar at electrochemical analyses guarantee the performance of these electrodes as EESE. Also, using fruit waste as the precursor of the EESE due to protect the environment and reduce environmental pollutions.

Sustainable Battery Materials from Biomass

Sustainable sources of energy have been identified as a possible way out of today's oil dependency and are being rapidly developed. In contrast, storage of energy to a large extent still relies on heavy metals in batteries. Especially when built from biomass-derived organics, organic batteries are promising alternatives and pave the way towards truly sustainable energy storage. First described in 2008, research on biomass-derived electrodes has been taken up by a multitude of researchers worldwide. Nowadays, in principle, electrodes in batteries could be composed of all kinds of carbonized and noncarbonized biomass: On one hand, all kinds of (waste) biomass may be carbonized and used in anodes of lithium- or sodium-ion batteries, cathodes in metal-sulfur or metal-oxygen batteries, or as conductive additives. On the other hand, a plethora of biomolecules, such as quinones, flavins, or carboxylates, contain redox-active groups that can be used as redox-active components in electrodes with very little chemical modification. Biomass-based binders can replace toxic halogenated commercial binders to enable a truly sustainable future of energy storage devices. Besides the electrodes, electrolytes and separators may also be synthesized from biomass. In this Review, recent research progress in this rapidly emerging field is summarized with a focus on potentially fully biowaste-derived batteries.

Biomass-derived activated carbon/sulfur composites as cathode electrodes for Li-S batteries by reducing the oxygen content

Corncob-derived activated carbon/sulfur as the cathode electrode for lithium sulfur batteries shows a good electrochemical performance, but the capacity fades rapidly with increase of cycle time. The experimental results demonstrate that such capacity fading is closely related to oxygen content of the activated carbon matrix. To investigate the effect of oxygen content on capacity fading, four carbon matrices (CAC, OAC, HAC, NAC) with different oxygen contents but similar surface areas and pore textures were obtained through a two-step method, namely, CAC was firstly oxygenated by nitric acid and then was reduced by H₂ or NH₃ at high temperature. The oxygen content of CAC, OAC, HAC and NAC was about 9.49 wt%, 20.41 wt%, 4.98 wt% and 4.74 wt%, respectively. Electrodes HAC/50S (H₂-treated carbon/sulfur composite with 50% sulfur) and NAC/50S with low oxygen content show a big improvement compared to the CAC/50S electrode. The HAC/50S and NAC/50S electrode deliver a high initial discharge of 1443 and 1504 mA h g⁻¹ respectively, which remain at 756 and 799 mA h g⁻¹ after 200 cycles at 0.3C, demonstrating a good cycle capacity and stability. It is believed that the carbon matrix with low oxygen content can effectively trap the lithium polysulfides within the carbon framework, weakening the shuttle effect and thus slowing down the capacity fade to a certain degree. Therefore, one of the effective routes to improve the electrochemical performance of Li–S batteries is to reduce the oxygen content.

Carbon matrix with low oxygen content can effectively trap the lithium polysulfides within carbon framework, weakening the shuttle effect and slowing down capacity fade in certain degree, improve the electrochemical performance of Li–S batteries.

Physical characteristics of capacitive carbons derived from the electrolytic reduction of alkali metal carbonate molten salts

Carbons have been synthesized through the reduction of molten carbonate systems under varied conditions. The mechanism and kinetics of carbon electrodeposition has been investigated. Carbon morphologies include amorphous, graphite-like, and spherical aggregate phases. Increased graphitic character is observed in carbons electrodeposited at more cathodic potentials, particularly at higher temperatures. Bonding has been investigated and oxygen functionalised sp2 and sp3 structures have been identified. The level of functionalization decreases in carbons with reduced amorphous and increased graphitic character. Thermal decomposition of electrodepositied carbons has been investigated and zero order kinetics have been identified. A relationship has been identified between elevated oxygen functionalization and increased pseudo-capacitance, with carbons deposited at 0.15 A cm-2 showing capacitances of 400 F g-1 in 0.5 M H2SO4 at sweep rates of 10 mV s-1.

Fabrication of Metal Molybdate Micro/Nanomaterials for Electrochemical Energy Storage

Currently, metal molybdates compounds can be prepared by several methods and are considered as prospective electrode materials in many fields because the metal ions possess the ability to exist in several oxidation states. These multiple oxidation states contribute to prolonging the discharge time, improving the energy density, and increasing the cycling stability. The high electrochemical performance of metal molybdates as electrochemical energy storage devices are discussed in this review. According to recent publications and research progress on relevant materials, the investigation of metal molybdate compounds are discussed via three main aspects: synthetic methods, material properties and measured electrochemical performance of these compounds as electrode materials. The recent progress in general metal molybdate nanomaterials for LIBs and supercapacitors are carefully presented here.

A review of recent developments in rechargeable lithium-sulfur batteries

The research and development of advanced energy-storage systems must meet a large number of requirements, including high energy density, natural abundance of the raw material, low cost and environmental friendliness, and particularly reasonable safety. As the demands of high-performance batteries are continuously increasing, with large-scale energy storage systems and electric mobility equipment, lithium-sulfur batteries have become an attractive candidate for the new generation of high-performance batteries due to their high theoretical capacity (1675 mA h g^-1) and energy density (2600 Wh kg^-1). However, rapid capacity attenuation with poor cycle and rate performances make the batteries far from ideal with respect to real commercial applications. Outstanding breakthroughs and achievements have been made to alleviate these problems in the past ten years. This paper presents an overview of recent advances in lithium-sulfur battery research. We cover the research and development to date on various components of lithium-sulfur batteries, including cathodes, binders, separators, electrolytes, anodes, collectors, and some novel cell configurations. The current trends in materials selection for batteries are reviewed and various choices of cathode, binder, electrolyte, separator, anode, and collector materials are discussed. The current challenges associated with the use of batteries and their materials selection are listed and future perspectives for this class of battery are also discussed.