Both the energy density and cycle stability are still challenges for lithium–sulfur (Li–S) batteries in future practical applications. Usually, light‐weight and nonpolar carbon materials are used as ...the hosts of sulfur, however they struggle on the cycle stability and undermine the volumetric energy density of Li–S batteries. Here, heavy NiCo2O4 nanofibers as carbon‐free sulfur immobilizers are introduced to fabricate sulfur‐based composites. NiCo2O4 can accelerate the catalytic conversion kinetics of soluble intermediate polysulfides by strong chemical interaction, leading to a good cycle stability of sulfur cathodes. Specifically, the S/NiCo2O4 composite presents a high gravimetric capacity of 1125 mAh g−1 at 0.1 C rate with the composite as active material, and a low fading rate of 0.039% per cycle over 1500 cycles at 1 C rate. In particular, the S/NiCo2O4 composite with the high tap density of 1.66 g cm−3 delivers large volumetric capacity of 1867 mAh cm−3, almost twice that of the conventional S/carbon composites.
NiCo2O4 nanofibers serve as carbon‐free sulfur hosts to fabricate sulfur‐based composites with high volumetric capacity based on the high tap density. Furthermore, NiCo2O4 can accelerate the catalytic conversion of soluble intermediate polysulfides by strong chemical interaction, leading to a good cycle stability. Therefore, S/NiCo2O4 composite presents tremendous advantages over conventional S/carbon materials in improving the volumetric capacity and cycle stability.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Abstract
Both the energy density and cycle stability are still challenges for lithium–sulfur (Li–S) batteries in future practical applications. Usually, light‐weight and nonpolar carbon materials are ...used as the hosts of sulfur, however they struggle on the cycle stability and undermine the volumetric energy density of Li–S batteries. Here, heavy NiCo
2
O
4
nanofibers as carbon‐free sulfur immobilizers are introduced to fabricate sulfur‐based composites. NiCo
2
O
4
can accelerate the catalytic conversion kinetics of soluble intermediate polysulfides by strong chemical interaction, leading to a good cycle stability of sulfur cathodes. Specifically, the S/NiCo
2
O
4
composite presents a high gravimetric capacity of 1125 mAh g
−1
at 0.1 C rate with the composite as active material, and a low fading rate of 0.039% per cycle over 1500 cycles at 1 C rate. In particular, the S/NiCo
2
O
4
composite with the high tap density of 1.66 g cm
−3
delivers large volumetric capacity of 1867 mAh cm
−3
, almost twice that of the conventional S/carbon composites.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Lithium–sulfur batteries are the most promising candidates for high energy battery systems due to their high theoretical energy density. However, the severe degradation of the lithium anode during ...cycling is a significant issue that hinders the practical application of lithium–sulfur batteries. Herein, a gel polymer electrolyte, fabricated via the self-polymerization of polydopamine (PDA) on the surface of polyvinylidene fluoride (PVDF) gel polymer electrolyte, was introduced for the first time to stabilize the lithium anode in a quasi-solid-state lithium–sulfur battery. Specifically, polydopamine with pyrrolic nitrogen in the structure is identified to be lithiophilic owing to its Lewis acid–base interactions. Such a lithiophilic gel polymer electrolyte plays a key role in regulating the nucleation and stripping/plating process of the lithium anode, leading to a smooth anode surface with a stable solid electrolyte interphase (SEI) during long-term cycling. Moreover, polydopamine is beneficial for confining polysulfides through their strong interaction, thus reducing the polysulfide side reaction with the anode. As a result, the quasi-solid-state cell with the multifunctional gel polymer electrolyte not only possesses a stable lithium anode, but also demonstrates excellent cycling performance. Moreover, the amount of electrolyte in the quasi-solid-state cell is lower compared with the conventional cell with a liquid electrolyte, which favors an increase in energy density of the battery.
A lithium–sulfur (Li–S) battery is widely regarded as one of the most promising technologies for energy storage because of its high theoretical energy density and cost advantage. However, the ...shuttling of soluble polysulfides between the cathode and the anode and the consequent lithium anode degradation strongly limit the safety and electrochemical performance in the Li–S battery. Herein, a metal–organic-framework (MOF)-modified gel polymer electrolyte (GPE) is employed in a Li–S battery in order to stablize the lithium anode. In view of the abundant pores in the MOF skeleton, the as-prepared GPE not only immobilizes the large-size polysulfide anions but also cages electrolyte anions into the pores, thus facilitating a uniform flux of Li ions and homogeneous Li deposition. Cooperated with a sulfur–carbon composite cathode, the lithium with MOF-modified GPE exhibits a uniform surface morphology and dense solid electrolyte interphase (SEI) film, thus delivering good cycle stability and high-rate capability.
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IJS, KILJ, NUK, PNG, UL, UM
•The polychaete-to-clitellate transition was a major event in annelid evolution.•Direct development emerged in the clitellate lineage.•Pattern of cell fate segregation is conserved between ...polychaetes and clitellates.•A heterochronic shift between cell lineages results in direct development.•Modularity in axial patterning mechanism enabled the heterochronic change.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Lithium–sulfur battery is recognized as one of the most promising next-generation energy storage devices. However, the low specific capacity and inferior cycling stability of cathode are real ...bottlenecks in practical lithium–sulfur battery, owing to the low sulfur content and tap density of cathode with light-weight and nonpolar carbon host materials. In this study, conductive RuO2 stacking microspheres are designed and demonstrated as sulfur immobilizer for lithium–sulfur battery. The stacked RuO2 microspheres exhibit not only good conductive framework for both the transport of electrons and diffusion of electrolyte, but outstanding electrocatalytic activity for the conversion of lithium polysulfides. Moreover, the polarity of RuO2 is helpful to trap and confine soluble polysulfides during cycling. With a high tap density of 1.4 g cm−3 and high sulfur content of 81.8 wt%, the S/RuO2 composite delivers a high gravimetric and volumetric capacity of 985 mAh g−1-composite and 1360 mAh cm−3-composite at 0.2 C rate, respectively. Resulting from the fast redox kinetics, an excellent rate capability of 479 mAh g−1-composite can be also obtained at 5 C rate. Overall, this work unfolds a potential strategy to realize the combination of high energy density and improved cycling stability of lithium–sulfur battery.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Aminopropyl triethoxysilane is introduced to tailor the organic/inorganic interfaces in the CSSE based on the –NH2 effect.•The hydrogen bond interaction between –NH2 and PEO can ...enhance the interface interaction.•Lone pair electrons on N can react with electron-deficient -CN in solvent ACN and promote the uniform dispersion of LLZAO.•Lone pair electrons on N can complex with Li+ and promote the dissociation of Li salts and uniform Li+ diffusion.
Composite solid-state electrolyte (CSSE) with integrated strengths avoids the weaknesses of organic and inorganic electrolytes, and thus become a better choice for all-solid-state lithium battery (ASSLB). However, the poor dispersion of inorganic fillers and the organic/inorganic nature difference leads to their interface incompatibility, which greatly destroys the performance of CSSE and ASSLB. Herein, silane coupling agent (SCA) aminopropyl triethoxysilane (ATS) is introduced to tailor the organic/inorganic interfaces in CSSE by the common chemical bridging effect of SCA and the special amino effect (hydrogen bond and lone pair electron effects). It is found that the hydrogen bond interaction between –NH2 and polyethylene oxide (PEO) enhances their interface interaction. And the lone pair electrons on nitrogen atom allow it to react with solvent acetonitrile and promote the uniform dispersion of ceramic fillers. Moreover, the lone pair electrons can complex with Li+, which promotes the dissociation of Li salts, uniforms Li+ diffusion and inhibits the Li dendrite. Thanks to the above merits, the interface compatibility and stability of organic/inorganic CSSE are much enhanced by innovatively introducing ATS, showing high ionic conductivity and superior mechanical/thermal stability. The ASSLB with this modified CSSE exhibits excellent electrochemical performance with a reversible capacity of 140.9 mAh g−1 and a capacity retention of 94.4% after 280 cycles. These achievements offer a new insight into improving the stability of organic/inorganic CSSE interface and promoting their applicability into ASSLB.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Leeches are a unique group of annelids arising from an ancestor that would be characterized as a freshwater oligochaete worm. Comparative biology of the oligochaetes and the leeches reveals that body ...plan changes in the oligochaete‐to‐leech transition probably occurred by addition or modification of the terminal steps in embryonic development and that they were likely driven by a change in the feeding behavior in the ancestor of leeches. In this review article, developmental changes that are associated with the evolution of several leech‐specific traits are discussed. These include (1) the evolution of suckers, (2) the loss of chaetae, (3) the loss of septa, and (4) a fixed number of segments. An altered developmental fate of the teloblast is further proposed to be a key factor contributing to the fixation of the segment number, and the evolutionary change in teloblast development may also account for the loss of the ability to regenerate the lost body segments in the leech.
Comparative biology of the oligochaetes and the leeches reveals that body plan changes in the oligochaete‐to‐leech transition probably occurred by addition or modification of the terminal steps in embryonic development and that they were likely driven by a change in the feeding behavior in the ancestor of leeches. In this review article, developmental changes that are associated with the evolution of several leech‐specific traits are discussed.
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DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
Current genomic perspectives on animal diversity neglect two prominent phyla, the molluscs and annelids, that together account for nearly one-third of known marine species and are important both ...ecologically and as experimental systems in classical embryology. Here we describe the draft genomes of the owl limpet (Lottia gigantea), a marine polychaete (Capitella teleta) and a freshwater leech (Helobdella robusta), and compare them with other animal genomes to investigate the origin and diversification of bilaterians from a genomic perspective. We find that the genome organization, gene structure and functional content of these species are more similar to those of some invertebrate deuterostome genomes (for example, amphioxus and sea urchin) than those of other protostomes that have been sequenced to date (flies, nematodes and flatworms). The conservation of these genomic features enables us to expand the inventory of genes present in the last common bilaterian ancestor, establish the tripartite diversification of bilaterians using multiple genomic characteristics and identify ancient conserved long- and short-range genetic linkages across metazoans. Superimposed on this broadly conserved pan-bilaterian background we find examples of lineage-specific genome evolution, including varying rates of rearrangement, intron gain and loss, expansions and contractions of gene families, and the evolution of clade-specific genes that produce the unique content of each genome.
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DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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