Energy‐storage technologies, including electrical double‐layer capacitors and rechargeable batteries, have attracted significant attention for applications in portable electronic devices, electric ...vehicles, bulk electricity storage at power stations, and “load leveling” of renewable sources, such as solar energy and wind power. Transforming lithium batteries and electric double‐layer capacitors requires a step change in the science underpinning these devices, including the discovery of new materials, new electrochemistry, and an increased understanding of the processes on which the devices depend. The Review will consider some of the current scientific issues underpinning lithium batteries and electric double‐layer capacitors.
TrueLi advanced: Modern energy storage technologies, such as lithium batteries and electrical double‐layer capacitors are a central area of basic research. The aims being to develop new materials and electrochemical reactions for these energy storage units and to better understand the underlying processes. Latest developments include the Li–air (see picture) and the Li–S batteries
While biomass waste is generated in abundance, these materials and their production processes are generally environmentally friendly, low cost, non-hazardous and easily scalable. These advantages ...position biomass materials as excellent candidates to solve problems of environmental pollution, primarily by substitution of less sustainable counterparts. This also applies to energy storage systems such as batteries, where several components have large environmental impacts. Lithium–Sulfur batteries have, in this context, been extensively researched to cope with the growing energy needs, and are expected to foresee a growing commercialization. Specifically, advances in the use of renewable cathode materials for Li–S batteries is a field that has been widely addressed in recent years, with carbonaceous materials (C) and/or activated carbons (AC), obtained from biomass, being intensively studied. We here reviewed this field through a classification and discussion of carbonaceous materials from natural waste according to the type of biomass: (1) woody, (2) herbaceous and agricultural, (3) aquatic, (4) animal and human, and (5) contaminated and industrial biomass waste materials. In addition, all porous carbons or activated carbons used as sulfur hosts have been exhaustively evaluated in terms of origin, synthesis parameters, physical properties, and electrochemical performance in Li–S batteries. The purpose is to provide a general description of the progress in the preparation of carbons from biomass resources, examine the textural and electrochemical properties of these materials focusing on the last decade, and also to present an outlook for future research in this developing area.
•The use of biomass and biowaste in Li-S batteries is reviewed.•Carbonaceous and activated carbons are discussed as sulfur hosts.•Woody, agricultural, aquatic, animal and industrial biomass waste is evaluated.•Critical parameters are defined for further progress in the field.
Despite their high theoretical capacity density (1675 mAh g–1), the application of Li–S batteries has been seriously hindered by the shuttle effect of polysulfides. Here, inspired by the working ...principle of natural spider webs, we synthesized a spider-web-like nanocomposite in which many hollow mesoporous silica (mSiO2) nanospheres/Co nanoparticles were threaded by interconnected nitrogen-doped carbon nanotubes (NCNTs). Then the nanocomposite (denoted as Co/mSiO2–NCNTs) was coated on the commercial separator by a simple infiltration to mitigate the above issue. The intimate combination of three-dimensional conductive networks (NCNTs) with abundant polysulfide adsorbent sites (SiO2 and N)/polysulfide conversion catalysts (Co and Co–N x species) allows the Co/mSiO2–NCNTs coating layer to not only effectively capture polysulfides via both physical confinement and chemical bonding but also accelerate the redox kinetics of polysulfides significantly. Furthermore, the combination of ex situ experiment and theoretical calculation demonstrates that the reversible adsorption/desorption of polysulfides on mSiO2 nanospheres benefits uniform deposition of Li2S2/Li2S on the conductive networks, which contributes to long-term cycling stability. As a result, Li–S batteries with Co/mSiO2–NCNTs-coated separators exhibited both excellent cycling stability and rate performance.
With the increasing demand for efficient and economic energy storage, Li‐S batteries have become attractive candidates for the next‐generation high‐energy rechargeable Li batteries because of their ...high theoretical energy density and cost effectiveness. Starting from a brief history of Li‐S batteries, this Review introduces the electrochemistry of Li‐S batteries, and discusses issues resulting from the electrochemistry, such as the electroactivity and the polysulfide dissolution. To address these critical issues, recent advances in Li‐S batteries are summarized, including the S cathode, Li anode, electrolyte, and new designs of Li‐S batteries with a metallic Li‐free anode. Constructing S molecules confined in the conductive microporous carbon materials to improve the cyclability of Li‐S batteries serves as a prospective strategy for the industry in the future.
Electrochemical cells with high energy densities are of great importance to satisfy the urgent demand for electronic vehicles and electricity storage. The Li‐S battery is one promising candidate, yet it suffers from the low utilization of active materials and poor cycle stability. The electrochemistry and challenges facing Li‐S batteries is addressed, and recent progress of materials related to Li‐S batteries is summarized.
Hybrid sp2 carbon with a graphene backbone and graphitic carbon nanocages (G‐GCNs) is demonstrated as an ideal host for sulfur in Li–S batteries, because it serves as highly efficient electrochemical ...nanoreactors as well as polysulfides reservoirs. The as‐obtained S/(G‐GCNs) with high S content exhibits superior high‐rate capability (765 mA h g−1 at 5 C) and long‐cycle life over 1000 cycles.
•The correlation between the properties of MOFs derivatives and ideal sulfur electrode parameters is reviewed.•The design principles of advanced sulfur cathodes and reaction process of sulfur on ...ideal cathode are proposed.•Typical regulatory strategies of MOFs derivatives for advanced sulfur cathodes are highlighted.•Future development trend on MOFs derivatives for advanced Li-S batteries is analyzed.
The commercialization of Li-S batteries is hampered by the poor conductivity of sulfur species, shuttle effects, and sluggish reaction kinetics. Due to their high porosity and specific surface area, abundantly exposed active sites, and interactive conductive networks, metal–organic frameworks (MOFs) derivatives have been used as efficient sulfur adsorbents and reaction promoters. Herein, this review clarifies the clear correlation between MOFs derivatives and advanced sulfur electrode to precisely guide the functional design of MOFs derivatives for stable and fast sulfur electrodes. First, the reaction mechanism, challenges, and design principles of sulfur electrodes in Li-S batteries are briefly summarized. Meanwhile, the significance of MOFs derivatives in advanced sulfur electrodes is emphasized. Second, the characteristics of MOFs derivatives are highlighted. On this basis, a bridge between problem-feature-function is proposed. Specifically, MOFs derivatives with morphology modulation, structural engineering, various composition regulation, and the corresponding electrochemical performance in Li-S batteries are highlighted, respectively. Finally, a perspective on the future development of MOFs derivatives for stable and fast sulfur electrodes are given. This review is expected to provide enlightening guidance for the design and understanding of MOFs derivatives in Li-S batteries.
Wearable electronics require lightweight and flexible batteries, of which lithium‐sulfur (Li‐S) batteries are of great interest due to their high gravimetric energy density. Nevertheless, flexible ...Li‐S batteries have unsatisfactory electrochemical performance owing to electrode fracture during repeated bending, the volume change of sulfur species and the severe shuttle effect. Binders play essential roles in these batteries but have always lacked attention. Herein, a self‐healing polyvinylpyrrolidone‐polyethyleneimine (PVP‐PEI) binder cross‐linked by hydrogen bonds, which also regulates polysulfide redox kinetics, is reported. The dynamic hydrogen‐bonding networks repair the cracks and ensure the integrity of the electrode while numerous polar groups such as CO and ‐NH2 suppress the shuttle effect by immobilizing polysulfides. Therefore, Li‐S batteries with the PVP‐PEI binder exhibit excellent cycling stability (a capacity decay rate of 0.0718% per cycle at 1 C after 450 cycles), an outstanding areal capacity of 7.67 mAh cm−2 even under a high sulfur loading (7.1 mg cm−2) and relatively lean electrolyte conditions (E/S ratio = 8 µL mg−1). Flexible Li‐S pouch cells using the PVP‐PEI binder show a stable performance for 140 cycles and a favorable capacity retention of over 95% after 2800 bending cycles, confirming its application potential in high‐performance flexible Li‐S batteries.
A water‐soluble, self‐healing, and polysulfide‐trapping binder named polyvinylpyrrolidone‐polyethyleneimine is reported and used in flexible lithium‐sulfur batteries to improve their electrochemical performance.
Sluggish redox kinetics, shuttle effect, poor conductivity, and large volume change of sulfur limit the practical applications of lithium‐sulfur batteries. Hollow, porous, and necklace‐like ...Fe3C/N‐codoped carbon nanoboxes (Fe3C/NC) connected by N‐doped carbon (NC) nanofibers are designed by pulverizing Fe2O3 embedded in polyacrylonitrile (PAN) fibers to produce multifunctional sulfur hosts, which exhibit multiple polysulfide anchoring and catalytic conversion activities. Experimental and first‐principles density functional theory studies reveal that the uniformly distributed Fe3C and N units in the nanoboxes can significantly suppress the polysulfide shuttle effect. The conversion of polysulfides (LiPSs) to Li2S is catalyzed during discharge. The process relies on the fast electron transfer through the NC nanofibers and facilitated Li+ diffusion through the porous nanobox shells. The structural characteristics (“boxes in fibers”) of the nanoboxes influence the high sulfur loading and tolerance of volume variation of LiPSs, resulting in the synergistic catalysis of the redox reactions. A high capacity of 645 mAh g−1 after 240 cycles at 1 C, a high capacity of 712 mAh g−1 at a high sulfur loading of 5 mg cm−2 after 100 cycles at 0.2 C, and an enhanced areal capacity of 3.6 mAh cm−2 are demonstrated.
Fe3C and N units present in the nanoboxes can significantly suppress the polysulfide shuttling effect and can catalyze the conversion of the polysulfides to Li2S under conditions of discharge. S8 is formed when charged. The process relies on the fast electron transfer through the N‐doped carbon nanofibers and facilitated Li+ diffusion through the porous shells of the nanoboxes.
Several critical issues, such as the shuttling effect and the sluggish reaction kinetics, exist in the design of high‐performance lithium–sulfur (Li‐S) batteries. Here, it is reported that nitrogen ...doping can simultaneously and significantly improve both the immobilization and catalyzation effects of Co9S8 nanoparticles in Li‐S batteries. Combining the theoretical calculations with experimental investigations, it is revealed that nitrogen atoms can increase the binding energies between LiPSs and Co9S8, and as well as alleviate the sluggish kinetics of Li‐S chemistry in the Li2S6 cathode. The same effects are also observed when adding N‐Co9S8 nanoparticles into the commercial Li2S cathode (which has various intrinsic advantages, but unfortunately a high overpotential). A remarkable improvement in the battery performances in both cases is observed. The work brings heteroatom‐doped Co9S8 to the attention of designing high‐performance Li‐S batteries. A fundamental understanding of the inhibition of LiPSs shuttle and the catalytic effect of Li2S in the newly developed system may encourage more effort along this interesting direction.
Nitrogen doping simultaneously and significantly improving the immobilization and catalyzation of the polysulfides by Co9S8 nanoparticles is reported. These N‐Co9S8 nanoparticles show effective suppression of the shuttling behavior, and as well as a significant acceleration of redox reaction kinetic in Li‐S batteries, especially the catalytic effect for Li2S.
For developing lithium–sulfur (Li–S) batteries, it is critical to design advanced cathode materials with high sulfur loading/utilization ratios and strong binding interactions with sulfur species to ...prevent the dissolution of intermediate polysulfides. Here we report an effective sulfur host material prepared by implanting cerium oxide (CeO2) nanocrystals homogeneously into well-designed bimodal micromesoporous nitrogen-rich carbon (MMNC) nanospheres. With the high conductivity and abundant hierarchical pore structures, MMNC nanospheres can effectively store and entrap sulfur species. Moreover, the inserted polar and electrocatalytically active CeO2 nanocrystals and high nitrogen content of MMNC can synergistically solve the hurdle of the polysulfide dissolution and furthermore significantly promote stable redox activity. By combining these advantages, CeO2/MMNC-S cathodes with 1.4 mg cm–2 sulfur exhibit high reversible capacities (1066 mAh g–1 at 0.2 C after 200 cycles and 836 mAh g–1 at 1.0 C after 500 cycles), good rate capability (737 mAh g–1 at 2.0 C), and high cycle stability (721 mAh g–1 at 2.0 C after 1000 cycles with a low capacity decay of 0.024% per cycle). Furthermore, a high and stable reversible capacity of 611 mAh g–1 is achieved after cycling for 200 cycles with higher sulfur loading of 3.4 mg cm–2.
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