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

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

All-Inorganic Perovskite Solar Cells

The research field on perovskite solar cells (PSCs) is seeing frequent record breaking in the power conversion efficiency (PCE). However, organic–inorganic hybrid halide perovskites and organic additives in common hole-transport materials (HTMs) exhibit poor stability against moisture and heat. Here we report the successful fabrication of all-inorganic PSCs without any labile or expensive organic components. The entire fabrication process can be operated in ambient environment without humidity control (e.g., a glovebox). Even without encapsulation, the all-inorganic PSCs present no performance degradation in humid air (90–95% relative humidity, 25 °C) for over 3 months (2640 h) and can endure extreme temperatures (100 and −22 °C). Moreover, by elimination of expensive HTMs and noble-metal electrodes, the cost was significantly reduced. The highest PCE of the first-generation all-inorganic PSCs reached 6.7%. This study opens the door for next-generation PSCs with long-term stability under harsh conditions, making practical application of PSCs a real possibility