Lithium–sulfur (Li–S) batteries are promising alternatives of conventional Li‐ion batteries attributed to their remarkable energy densities and high sustainability. However, the practical ...applications of Li–S batteries are hindered by the shuttling effect of lithium polysulfides (LiPSs) on cathode and the Li dendrite formation on anode, which together leads to inferior rate capability and cycling stability. Here, an advanced N‐doped carbon microreactors embedded with abundant Co3O4/ZnO heterojunctions (CZO/HNC) are designed as dual‐functional hosts for synergistic optimization of both S cathode and Li metal anode. Electrochemical characterization and theoretical calculations confirm that CZO/HNC exhibits an optimized band structure that effectively facilitates ion diffusion and promotes bidirectional LiPSs conversion. In addition, the lithiophilic nitrogen dopants and Co3O4/ZnO sites together regulate dendrite‐free Li deposition. The S@CZO/HNC cathode exhibits excellent cycling stability at 2 C with only 0.039% capacity fading per cycle over 1400 cycles, and the symmetrical Li@CZO/HNC cell enables stable Li plating/striping behavior for 400 h. Remarkably, Li‐S full cell using CZO/HNC as both cathode and anode hosts shows an impressive cycle life of over 1000 cycles. This work provides an exemplification of designing high‐performance heterojunctions for simultaneous protection of two electrodes, and will inspire the applications of practical Li–S batteries.
An advanced microreactor embedded with Co3O4/ZnO heterojunctions (CZO/HNC) is designed as dual‐functional hosts for synergistic optimization of both S cathode and Li anode. Electrochemical characterization and theoretical calculations confirm that CZO/HNC exhibits an optimized band structure that effectively facilitates ion diffusion and promotes polysulfides conversion. In addition, the lithiophilic nitrogen dopants and Co3O4/ZnO sites together regulate dendrite‐free Li deposition.
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•A novel 2D/2D heterostructure was developed.•The heterostructure plays a synergistic adsorption-electrocatalysis role.•The heterostructure exhibits a superior reversible ...capacity.•The heterostructure has remarkable cycling stability.
The shuttle effect of polysulfides and sluggish reaction kinetics have become current major obstacles for the development of lithium-sulfur (Li-S) batteries. Herein, a novel 2D/2D heterostructure, consisting of ultrathin Ni-Co MOFs with rich unsaturated metal sites and conductive Ti3C2Tx nanosheets (Ti3C2Tx/Ni-Co MOF), is developed as a multifunctional barrier coated on commercial separators for Li-S batteries. Based on the synergistic adsorption-electrocatalysis, the modified separators not only suppress the dissolution of polysulfides and promote their conversion effectively, but also accelerate the electron/ion transfer. Moreover, density functional theory results further confirm that the heterostructure has strong adsorption energy for polysulfides and low energy barriers for their conversion. Li-S batteries with the Ti3C2Tx/Ni-Co MOF heterostructure modified separators exhibit an excellent reversible capacity of 1260 mAh g−1 at 0.2C and a remarkable cycling stability with capacity retention of 91.1 % at 0.5C after 350 cycles. When equipped with high sulfur loading of 5.8 mg cm−2 and low electrolyte/sulfur ratio of 4 uL mg−1, the cell maintains a superior capacity. This work provides a new route to the design of modified separators for high performance Li-S batteries with especially remarkable cycling stability.
Selenium-sulfur solid solutions (SexSy) attracts soaring attention owing to its improved electrical conductivity over sulfur and higher theoretical specific capacity than selenium. Herein, ...high-performance lithium-selenium/sulfur batteries with a dual-confined cathode configuration by encapsulating SeS2 in double-layered hollow micro/mesoporous carbon spheres (DSMCs) with a conductive polyaniline (PANI) protection sheath are proposed. Polysulfides/polyselenides are efficiently restricted in the cathode via physical and chemical entrapment from DSMCs and PANI as well as chemical binding between selenium and sulfur. Benefiting from the distinct advantages of SeS2 and the well-constructed host framework, the cathode achieves high capacity utilization of 1018 mAh g−1 at 0.2 A g−1, together with outstanding rate capability of 619 mAh g−1 at 2 A g−1 and excellent cycle life over 500 cycles with almost 100% Coulombic efficiency. The novel SexSy-based cathode demonstrates a promising route to surmount some bottlenecks of current lithium-sulfur systems for high-performance rechargeable batteries.
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•Constructing SeS2 cathode within dual-confined nanoreactors.•Integrate physical barrier and chemical interaction to inhibit the shuttle effect.•Excellent Li–SeS2 battery electrochemical performance was achieved.
Nanostructured sulfur cathode with a multiple core-shelled structure, featured with the spherical double-layered hollow carbon/sulfur composite (DLHC/S) coated with a conductive layer of ...poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), is designed and synthesized for lithium-sulfur batteries. Transmission electron microscope images of DLHC/S single nanoparticle show that the sulfur aggregates predominantly in the interior space between the two carbon shells by using a vacuum infiltration process. The electric conductivity of DLHC/S@PEDOT:PSS increases over 5 times as comparing to DLHC/S without PEDOT:PSS coating. The composite cathode exhibits a high reversible capacity of 1089 mAh g−1 at 0.2C and superior rate capacity of 510 mAh g−1 even at 4 C, and also remarkable cycling stability with a capacity decay of 0.097% per cycle after 500 cycles at 1 C. The excellent electrochemical performances for DLHC/S@PEDOT:PSS cathode are primarily attributed to the engineering of the unique multiple core-shell structure of DLHC/S@PEDOT:PSS, which inhibits the sulfur dissolution into the electrolyte and the polysulfide shuttle effect, together with the conductivity enhancement due to PEDOT:PSS coating.
•Nanostructured multiple core-shelled sulfur cathode with PEDOT:PSS coating was prepared.•Introducing sulfur into the interlayer of DLHC via a vacuum infiltration process.•Inhibiting the sulfur dissolution into the electrolyte and the polysulfide shuttle effect.•DLHC/S@PEDOT:PSS cathode exhibited outstanding electrochemical performance.
The shuttle effect of polysulfides and sluggish reaction kinetics have been the main obstacles for the practical applications of lithium-sulfur (Li-S) batteries. Herein, we report a rationally ...designed sulfur cathode (DLHC/S@MnO2-ACNT) based on double-layered hollow carbon sphere (DLHC) decorated with manganese dioxide (MnO2) shielding layer and carbon nanotube conductive network (ACNT). The Ultramicrotome technique demonstrates that S and MnO2 nanosheets are mainly located into the interlayer of the DLHC. In the elaborate nanostructured protocol, the interlayer MnO2 nanosheets catalyze the conversion of polysulfides and the surface MnO2 nanosheets effectively adsorb polysulfides to suppress the shuttle effect. Additionally, the ACNT conductive network facilitates electrons/ions transport. Benefiting from the hierarchical confinement, Li-S batteries with DLHC/S@MnO2-ACNT composite cathodes exhibit a high reversible capacity of 1051 mAh g−1 at 0.5 C and a remarkable cycling stability over 500 cycles at 1 C. Even at a high sulfur loading of 4 mg cm−2, the cell delivers a superior areal capacity of 4.47 mAh cm−2. This work provides a new route to the design of hierarchical confinement sulfur hosts for high-performance Li-S batteries.
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Silicon oxycarbonitride (SiOCN) composites with different carbon contents were synthesized by pyrolysis of precursors generated from aldimine condensation of 3-aminopropyltriethoxysilane (APTES) with ...different aldehydes and simultaneous hydrolysis of APTES. Both SiOCN-1 and SiOCN-5 composites, derived from formaldehyde and glutaraldehyde respectively, display similar bulky structure composed by aggregated nanospheres with a diameter of 70–100 nm. SiOCN-5 has a higher carbon content of 30.4% than 15.9% for SiOCN-1, while a lower specific surface area of 38.2 m2 g−1 than 76.0 m2 g−1 for SiOCN-1. SiOCN/S cathodes with sulfur loading of 1.2–1.5 mg cm−2 were fabricated using SiOCN as sulfur host on different current collector of aluminum foil (AL) or carbon paper (CP). When using aluminum foil as current collector, SiOCN-5/S-AL cathode exhibits better electrochemical performance than SiOCN-1/S-AL, primarily due to the higher electrical conductivity of SiOCN-5 comparing with SiOCN-1. When using porous carbon paper as current collector, SiOCN-5/S-CP cathode shows the best cycling performance with a discharge capacity of 648.9 mA h g−1 at 0.2C after 100 cycles. Even at a high rate of 1C, SiOCN-5/S-CP also exhibits an excellent cycling stability, delivering a reversible discharge capacity of 374.5 mA h g−1 after 500 cycles with a capacity retention of 73.0%.
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•Nanostructured SiOCNs were synthesized and applied as a new category of cathode host for lithium-sulfur batteries.•The higher electrical conductivity of SiOCN host triggers an enhanced discharge capacity.•The employment of carbon paper as current collector will further elevate the electrochemical performance of SiOCN/S cathodes.
Most catalysts cannot accelerate uninterrupted conversion of polysulfides, resulting in poor long-cycle and high-loading performance of lithium-sulfur (Li-S) batteries. Herein, rich p-n junction CoS
.../ZnS heterostructures embedded on N-doped carbon nanosheets are fabricated by ion-etching and vulcanization as a continuous and efficient bidirectional catalyst. The p-n junction built-in electric field in the CoS
/ZnS heterostructure not only accelerates the transformation of lithium polysulfides (LiPSs), but also promotes the diffusion and decomposition for Li
S the from CoS
to ZnS avoiding the aggregation of lithium sulfide (Li
S). Meanwhile, the heterostructure possesses a strong chemisorption ability to anchor LiPSs and superior affinity to induce homogeneous Li deposition. The assembled cell with a CoS
/ZnS@PP separator delivers a cycling stability with a capacity decay of 0.058% per cycle at 1.0 C after 1000 cycles, and a decent areal capacity of 8.97 mA h cm
at an ultrahigh sulfur mass loading of 6 mg cm
. This work reveals that the catalyst continuously and efficiently converts polysulfides via abundant built-in electric fields to promote Li-S chemistry.
Searching for new promising electrocatalysts with favorable architectures allowing abundant active sites and remarkable structure stability is an urgent task for the practical application of ...lithium-sulfur (Li−S) batteries. Herein, inspired by the structure of natural cactus, a new efficient and robust electrocatalyst with three-dimensional (3D) hierarchical cactus-like architecture constructed by functional zero-dimensional (0D), one-dimensional (1D), and two-dimensional (2D) components is developed. The cactus-inspired catalyst (denoted as Co@NCNT/NCNS) consists of N-doped carbon nanosheets (NCNS) and standing N-doped carbon nanotubes (NCNT) forest with embedded Co nanoparticles on the top of NCNT, which was achieved by an
in situ
catalytic growth technique. The unique structure design integrates the advantages of 0D Co accelerating catalytic redox reactions, 1D NCNT providing a fast electron pathway, and 2D NCNS assuring strong structure stability. Especially, the rich Mott-Schottky heterointerfaces between metallic Co and semiconductive NCNT can further facilitate the electron transfer, thus improving the electrocatalyst activity. Consequently, a Li−S battery with the Co@NCNT/NCNS modified separator achieves ultralong cycle life over 4000 cycles at 2 C with ultralow capacity decay of 0.016% per cycle, much superior over that of recently reported batteries. This work provides a new strategy for developing ultra-stable catalysts towards long-life Li−S batteries.
Designing and synthesizing high-activity, durable, and low-cost catalysts for the electrochemically transformation of water to hydrogen are vitally important to future energy systems. Herein, a ...simple but effective strategy for manganese-metal-heteroatom doping is adopted to intrinsically elevate the electrocatalytic activities of SnS2 nanosheets by a facile two steps hydrothermal-sulfurization approach. Electrocatalytic hydrogen evolution (HER) performance of Mn–SnS2 nanosheets grown on 3D nickel foam (Mn–SnS2/NF) is efficiently optimized since the dopants and defects endow the Mn–SnS2/NF vast active sites. An overpotential as low as 71 mV is required to drive a current density of 10 mA/cm2 with a low Tafel slope of 72 mV dec−1 in alkaline environment (1 M KOH). In addition, the Mn–SnS2/NF exhibits prominent stability in 1 M KOH electrolyte, which is an indispensable index for the potential HER electrocatalysts. The present work demonstrates that the heteroatom manganese doping strategy renders a meaningful route for synthesizing cost-efficient HER electrocatalysts in alkaline condition.
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•The Mn–SnS2/NF nanosheets had rich defects induced by Mn dopants.•The optimal atomic ratio of Mn dopants was 6.9%.•The Mn dopants and defects contributed the drastically enhanced electrochemical HER activity.•Mn–SnS2/NF only required an overpotential as small as 71 mV to drive a current density of 10 mA cm−2.•Mn–SnS2/NF had exhibited remarkable stability and long-term durability of 24h.
