Cerium Oxide Nanocrystal Embedded Bimodal Micromesoporous Nitrogen-Rich Carbon Nanospheres as Effective Sulfur Host for Lithium–Sulfur Batteries

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

CsPb_0.9Sn_0.1IBr₂ Based All-Inorganic Perovskite Solar Cells with Exceptional Efficiency and Stability

The emergence of perovskite solar cells (PSCs) has generated enormous interest in the photovoltaic research community. Recently, cesium metal halides (CsMX₃, M = Pb or Sn; X = I, Br, Cl or mixed halides) as a class of inorganic perovskites showed great promise for PSCs and other optoelectronic devices. However, CsMX₃-based PSCs usually exhibit lower power conversion efficiencies (PCEs) than organic–inorganic hybrid PSCs, due to the unfavorable band gaps. Herein, a novel mixed-Pb/Sn mixed-halide inorganic perovskite, CsPb_0.9Sn_0.1IBr₂, with a suitable band gap of 1.79 eV and an appropriate level of valence band maximum, was prepared in ambient atmosphere without a glovebox. After thoroughly eliminating labile organic components and noble metals, the all-inorganic PSCs based on CsPb_0.9Sn_0.1IBr₂ and carbon counter electrodes exhibit a high open-circuit voltage of 1.26 V and a remarkable PCE up to 11.33%, which is record-breaking among the existing CsMX₃-based PSCs. Moreover, the all-inorganic PSCs show good long-term stability and improved endurance against heat and moisture. This study indicates a feasible way to design inorganic halide perovskites through energy-band engineering for the construction of high-performance all-inorganic PSCs

Self-Templated Formation of Interlaced Carbon Nanotubes Threaded Hollow Co₃S₄ Nanoboxes for High-Rate and Heat-Resistant Lithium–Sulfur Batteries

Lithium–sulfur batteries (Li–S) have attracted soaring attention due to the particularly high energy density for advanced energy storage system. However, the practical application of Li–S batteries still faces multiple challenges, including the shuttle effect of intermediate polysulfides, the low conductivity of sulfur and the large volume variation of sulfur cathode. To overcome these issues, here we reported a self-templated approach to prepare interconnected carbon nanotubes inserted/wired hollow Co₃S₄ nanoboxes (CNTs/Co₃S₄–NBs) as an efficient sulfur host material. Originating from the combination of three-dimensional CNT conductive network and polar Co₃S₄–NBs, the obtained hybrid nanocomposite of CNTs/Co₃S₄–NBs can offer ultrahigh charge transfer properties, and efficiently restrain polysulfides in hollow Co₃S₄–NBs via the synergistic effect of structural confinement and chemical bonding. Benefiting from the above advantages, the S@CNTs/Co₃S₄–NBs cathode shows a significantly improved electrochemical performance in terms of high reversible capacity, good rate performance, and long-term cyclability. More remarkably, even at an elevated temperature (50 °C), it still exhibits high capacity retention and good rate capacity

Strong Capillarity, Chemisorption, and Electrocatalytic Capability of Crisscrossed Nanostraws Enabled Flexible, High-Rate, and Long-Cycling Lithium–Sulfur Batteries

The development of flexible lithium–sulfur (Li–S) batteries with high energy density and long cycling life are very appealing for the emerging flexible, portable, and wearable electronics. However, the progress on flexible Li–S batteries was limited by the poor flexibility and serious performance decay of existing sulfur composite cathodes. Herein, we report a freestanding and highly flexible sulfur host that can simultaneously meet the flexibility, stability, and capacity requirements of flexible Li–S batteries. The host consists of a crisscrossed network of carbon nanotubes reinforced CoS nanostraws (CNTs/CoS-NSs). The CNTs/CoS-NSs with large inner space and high conductivity enable high loading and efficient utilization of sulfur. The strong capillarity effect and chemisorption of CNTs/CoS-NSs to sulfur species were verified, which can efficiently suppress the shuttle effect and promote the redox kinetics of polysulfides. The sulfur-encapsulated CNTs/CoS-NSs (S@CNTs/CoS-NSs) cathode in Li–S batteries exhibits superior performance, including high discharge capacity, rate capability (1045 mAh g^–1 at 0.5 C and 573 mAh g^–1 at 5.0 C), and cycling stability. Intriguingly, the soft-packed Li–S batteries based on S@CNTs/CoS-NSs cathode show good flexibility and stability upon bending

Highly Efficient Retention of Polysulfides in “Sea Urchin”-Like Carbon Nanotube/Nanopolyhedra Superstructures as Cathode Material for Ultralong-Life Lithium–Sulfur Batteries

Despite high theoretical energy density, the practical deployment of lithium–sulfur (Li–S) batteries is still not implemented because of the severe capacity decay caused by polysulfide shuttling and the poor rate capability induced by low electrical conductivity of sulfur. Herein, we report a novel sulfur host material based on “sea urchin”-like cobalt nanoparticle embedded and nitrogen-doped carbon nanotube/nanopolyhedra (Co-NCNT/NP) superstructures for Li–S batteries. The hierarchical micromesopores in Co-NCNT/NP can allow efficient impregnation of sulfur and block diffusion of soluble polysulfides by physical confinement, and the incorporation of embedded Co nanoparticles and nitrogen doping (∼4.6 at. %) can synergistically improve the adsorption of polysulfides, as evidenced by beaker cell tests. Moreover, the conductive networks of Co-NCNT/NP interconnected by nitrogen-doped carbon nanotubes (NCNTs) can facilitate electron transport and electrolyte infiltration. Therefore, the specific capacity, rate capability, and cycle stability of Li–S batteries are significantly enhanced. As a result, the Co-NCNT/NP based cathode (loaded with 80 wt % sulfur) delivers a high discharge capacity of 1240 mAh g^–1 after 100 cycles at 0.1 C (based on the weight of sulfur), high rate capacity (755 mAh g^–1 at 2.0 C), and ultralong cycling life (a very low capacity decay of 0.026% per cycle over 1500 cycles at 1.0 C). Remarkably, the composite cathode with high areal sulfur loading of 3.2 mg cm^–2 shows high rate capacities and stable cycling performance over 200 cycles

Porous-Shell Vanadium Nitride Nanobubbles with Ultrahigh Areal Sulfur Loading for High-Capacity and Long-Life Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries hold great promise for the applications of high energy density storage. However, the performances of Li–S batteries are restricted by the low electrical conductivity of sulfur and shuttle effect of intermediate polysulfides. Moreover, the areal loading weights of sulfur in previous studies are usually low (around 1–3 mg cm^–2) and thus cannot fulfill the requirement for practical deployment. Herein, we report that porous-shell vanadium nitride nanobubbles (VN-NBs) can serve as an efficient sulfur host in Li–S batteries, exhibiting remarkable electrochemical performances even with ultrahigh areal sulfur loading weights (5.4–6.8 mg cm^–2). The large inner space of VN-NBs can afford a high sulfur content and accommodate the volume expansion, and the high electrical conductivity of VN-NBs ensures the effective utilization and fast redox kinetics of polysulfides. Moreover, VN-NBs present strong chemical affinity/adsorption with polysulfides and thus can efficiently suppress the shuttle effect via both capillary confinement and chemical binding, and promote the fast conversion of polysulfides. Benefiting from the above merits, the Li–S batteries based on sulfur-filled VN-NBs cathodes with 5.4 mg cm^–2 sulfur exhibit impressively high areal/specific capacity (5.81 mAh cm^–2), superior rate capability (632 mAh g^–1 at 5.0 C), and long cycling stability

High-Performance Li–Se Batteries Enabled by Selenium Storage in Bottom-Up Synthesized Nitrogen-Doped Carbon Scaffolds

Selenium (Se) has great promise to serve as cathode material for rechargeable batteries because of its good conductivity and high theoretical volumetric energy density comparable to sulfur. Herein, we report the preparation of mesoporous nitrogen-doped carbon scaffolds (NCSs) to restrain selenium for advanced lithium–selenium (Li–Se) batteries. The NCSs synthesized by a bottom-up solution-phase method have graphene-like laminar structure and well-distributed mesopores. The unique architecture of NCSs can severe as conductive framework for encapsulating selenium and polyselenides, and provide sufficient pathways to facilitate ion transport. Furthermore, the laminar and porous NCSs can effectively buffer the volume variation during charge/discharge processes. The integrated composite of Se-NCSs has a high Se content and can ensure the complete electrochemical reactions of Se and Li species. When used for Li–Se batteries, the cathodes based on Se-NCSs exhibit high capacity, remarkable cyclability, and excellent rate performance

Hierarchical Ternary Carbide Nanoparticle/Carbon Nanotube-Inserted N‑Doped Carbon Concave-Polyhedrons for Efficient Lithium and Sodium Storage

Here, we report a hierarchical Co₃ZnC/carbon nanotube-inserted nitrogen-doped carbon concave-polyhedrons synthesized by direct pyrolysis of bimetallic zeolitic imidazolate framework precursors under a flow of Ar/H₂ and subsequent calcination for both high-performance rechargeable Li-ion and Na-ion batteries. In this structure, Co₃ZnC nanoparticles were homogeneously distributed in in situ growth carbon nanotube-inserted nitrogen-doped carbon concave-polyhedrons. Such a hierarchical structure offers a synergistic effect to withstand the volume variation and inhibit the aggregation of Co₃ZnC nanoparticles during long-term cycles. Meanwhile, the nitrogen-doped carbon and carbon nanotubes in the hierarchical Co₃ZnC/carbon composite offer fast electron transportation to achieve excellent rate capability. As anode of Li-ion batteries, the electrode delivered a high reversible capacity (∼800 mA h/g at 0.5 A/g), outstanding high-rate capacity (408 mA h/g at 5.0 A/g), and long-term cycling performance (585 mA h/g after 1500 cycles at 2.0 A/g). In Na-ion batteries, the Co₃ZnC/carbon composite maintains a stable capacity of 386 mA h/g at 1.0 A/g without obvious decay over 750 cycles and a superior rate capability (∼500, 448, and 415 mA h/g at 0.2, 0.5, and 1.0 A/g, respectively)

Correction to Highly Efficient Retention of Polysulfides in “Sea-Urchin”-Like Carbon Nanotube/Nanopolyhedra Superstructures as Cathode Material for Ultralong-Life Lithium–Sulfur Batteries

Correction to Highly Efficient Retention of Polysulfides in “Sea-Urchin”-Like Carbon Nanotube/Nanopolyhedra Superstructures as Cathode Material for Ultralong-Life Lithium–Sulfur Batterie

In Situ Thermal Synthesis of Inlaid Ultrathin MoS₂/Graphene Nanosheets as Electrocatalysts for the Hydrogen Evolution Reaction

Herein, we report a unique thermal synthesis method to prepare a novel two-dimensional (2D) hybrid nanostructure consisting of ultrathin and tiny-sized molybdenum disulfide nanoplatelets homogeneously inlaid in graphene sheets (MoS₂/G) with excellent electrocatalytic performance for HER. In this process, molybdenum oleate served as the source of both molybdenum and carbon, while crystalline sodium sulfate (Na₂SO₄) served as both reaction template and sulfur source. The remarkable integration of MoS₂ and graphene in a well-assembled 2D hybrid architecture provided large electrochemically active surface area and a huge number of active sites and also exhibited extraordinary collective properties for electron transport and H⁺ trapping. The MoS₂/G inlaid nanosheets deliver ultrahigh catalytic activity toward HER among the existing electrocatalysts with similar compositions, presenting a low onset overpotential approaching 30 mV, a current density of 10 mA/cm² at ∼110 mV, and a Tafel slope as small as 67.4 mV/dec. Moreover, the strong bonding between MoS₂ nanoplatelets and graphene enabled outstanding long-term electrochemical stability and structural integrity, exhibiting almost 100% activity retention after 1000 cycles and ∼97% after 100 000 s of continuous testing (under static overpotential of −0.15 V). The synthetic strategy is simple, inexpensive, and scalable for large-scale production and also can be extended to diverse inlaid 2D nanoarchitectures with great potential for many other applications