Parametric All-Optical Modulation on Chip

We demonstrate parametric all-optical modulation in a periodically-poled lithium niobate microring resonator on chip. It employs quantum Zeno blockade between two distinct waves, a signal and a pump, through their sum-frequency generation at a large per-photon efficiency of 8.2 MHz. With nanosecond pump pulses at 6 mW peak power, 85.7% modulation extinction is observed, marking over 30~times efficiency improvement across various previous implementations. With only 2 mW pump peak power, 43.0% modulation extinction is observed for a doubly-stronger signal at 4 mW. This demonstrates, for the first time, that optical transistors with cascadability and fan-out are possible with just parametric nonlinear optics. These results, together with inherent advantages in such photonic integrated circuits, open the door to scalable technology for all-optical and quantum information processing

High-Performance All-Inorganic Solid-State Sodium–Sulfur Battery

All-inorganic solid-state sodium–sulfur batteries (ASSBs) are promising technology for stationary energy storage due to their high safety, high energy, and abundant resources of both sodium and sulfur. However, current ASSB shows poor cycling and rate performances mainly due to the huge electrode/electrolyte interfacial resistance arising from the insufficient triple-phase contact among sulfur active material, ionic conductive solid electrolyte, and electronic conductive carbon. Herein, we report an innovative approach to address the interfacial problem using a Na₃PS₄–Na₂S–C (carbon) nanocomposite as the cathode for ASSBs. Highly ionic conductive Na₃PS₄ contained in the nanocomposite can function as both solid electrolyte and active material (catholyte) after mixing with electronic conductive carbon, leading to an intrinsic superior electrode/electrolyte interfacial contact because only a two-phase contact is required for the charge transfer reaction. Introducing nanosized Na₂S into the nanocomposite cathode can effectively improve the capacity. The homogeneous distribution of nanosized Na₂S, Na₃PS₄, and carbon in the nanocomposite cathode could ensure a high mixed (ionic and electronic) conductivity and a sufficient interfacial contact. The Na₃PS₄-nanosized Na₂S–carbon nanocomposite cathode delivered a high initial discharge capacity of 869.2 mAh g^–1 at 50 mA g^–1 with great cycling and rate capabilities at 60 °C, representing the best performance of ASSBs reported to date and therefore constituting a significant step toward high-performance ASSBs for practical applications

High-Performance All-Solid-State Lithium–Sulfur Battery Enabled by a Mixed-Conductive Li₂S Nanocomposite

All-solid-state lithium–sulfur batteries (ASSLSBs) using highly conductive sulfide-based solid electrolytes suffer from low sulfur utilization, poor cycle life, and low rate performance due to the huge volume change of the electrode and the poor electronic and ionic conductivities of S and Li₂S. The most promising approach to mitigate these challenges lies in the fabrication of a sulfur nanocomposite electrode consisting of a homogeneous distribution of nanosized active material, solid electrolyte, and carbon. Here, we reported a novel bottom-up method to synthesize such a nanocomposite by dissolving Li₂S as the active material, polyvinylpyrrolidone (PVP) as the carbon precursor, and Li₆PS₅Cl as the solid electrolyte in ethanol, followed by a coprecipitation and high-temperature carbonization process. Li₂S active material and Li₆PS₅Cl solid electrolyte with a particle size of ∼4 nm were uniformly confined in a nanoscale carbon matrix. The homogeneous nanocomposite electrode consisting of different nanoparticles with distinct properties of lithium storage capability, mechanical reinforcement, and ionic and electronic conductivities enabled a mechanical robust and mixed conductive (ionic and electronic conductive) sulfur electrode for ASSLSB. A large reversible capacity of 830 mAh/g (71% utilization of Li₂S) at 50 mA/g for 60 cycles with a high rate performance was achieved at room temperature even at a high loading of Li₂S (∼3.6 mg/cm²). This work provides a new strategy to design a mechanically robust, mixed conductive nanocomposite electrode for high-performance all-solid-state lithium sulfur batteries

Preparation of High-Quality Colloidal Mask for Nanosphere Lithography by a Combination of Air/Water Interface Self-Assembly and Solvent Vapor Annealing

Nanosphere lithography (NSL) has been regarded as an inexpensive, inherently parallel, high-throughput, materials-general approach to the fabrication of nanoparticle arrays. However, the order of the resulting nanoparticle array is essentially dependent on the quality of the colloidal monolayer mask. Furthermore, the lateral feature size of the nanoparticles created using NSL is coupled with the diameter of the colloidal spheres, which makes it inconvenient for studying the size-dependent properties of nanoparticles. In this work, we demonstrate a facile approach to the fabrication of a large-area, transferrable, high-quality latex colloidal mask for nanosphere lithography. The approach is based on a combination of the air/water interface self-assembly method and the solvent-vapor-annealing technique. It enables the fabrication of colloidal masks with a higher crystalline integrity compared to those produced by other strategies. By manipulating the diameter of the colloidal spheres and precisely tuning the solvent-vapor-annealing process, flexible control of the size, shape, and spacing of the interstice in a colloidal mask can be realized, which may facilitate the broad use of NSL in studying the size-, shape-, and period-dependent optical, magnetic, electronic, and catalytic properties of nanomaterials

High-Voltage Aqueous Magnesium Ion Batteries

Nonaqueous rechargeable magnesium (Mg) batteries suffer from the complicated and moisture-sensitive electrolyte chemistry. Besides electrolytes, the practicality of a Mg battery is also confined by the absence of high-performance electrode materials due to the intrinsically slow Mg²⁺ diffusion in the solids. In this work, we demonstrated a rechargeable aqueous magnesium ion battery (AMIB) concept of high energy density, fast kinetics, and reversibility. Using a superconcentration approach we expanded the electrochemical stability window of the aqueous electrolyte to 2.0 V. More importantly, two new Mg ion host materials, Li superconcentration approach we expanded the electrochemical stability window of the aqueous electrolyte to 2.0 V. More importantly, two new Mg ion host materials, Li₃V₂(PO₄)₃ and poly pyromellitic dianhydride, were developed and employed as cathode and anode electrodes, respectively. Based on comparisons of the aqueous and nonaqueous systems, the role of water is identified to be critical in the Mg ion mobility in the intercalation host but remaining little detrimental to its non-diffusion controlled process. Compared with the previously reported Mg ion cell delivers an unprecedented high power density of 6400 W kg ion cell delivers an unprecedented high power density of 6400 W kg while retaining 92% of the initial capacity after 6000 cycles, pushing the Mg ion cell to a brand new stage

Reverse Microemulsion Synthesis of Sulfur/Graphene Composite for Lithium/Sulfur Batteries

Due to its high theoretical capacity, high energy density, and easy availability, the lithium–sulfur (Li–S) system is considered to be the most promising candidate for electric and hybrid electric vehicle applications. Sulfur/carbon cathode in Li–S batteries still suffers, however, from low Coulombic efficiency and poor cycle life when sulfur loading and the ratio of sulfur to carbon are high. Here, we address these challenges by fabricating a sulfur/carboxylated–graphene composite using a reverse (water-in-oil) microemulsion technique. The fabricated sulfur–graphene composite cathode, which contains only 6 wt % graphene, can dramatically improve the cycling stability as well as provide high capacity. The electrochemical performance of the sulfur–graphene composite is further enhanced after loading into a three-dimensional heteroatom-doped (boron and nitrogen) carbon-cloth current collector. Even at high sulfur loading (∼8 mg/cm²) on carbon cloth, this composite showed 1256 mAh/g discharge capacity with more than 99% capacity retention after 200 cycles

Zn/MnO₂ Battery Chemistry With H⁺ and Zn²⁺ Coinsertion

Rechargeable aqueous Zn/MnO₂ battery chemistry in a neutral or mildly acidic electrolyte has attracted extensive attention recently because all the components (anode, cathode, and electrolyte) in a Zn/MnO₂ battery are safe, abundant, and sustainable. However, the reaction mechanism of the MnO₂ cathode remains a topic of discussion. Herein, we design a highly reversible aqueous Zn/MnO₂ battery where the binder-free MnO₂ cathode was fabricated by in situ electrodeposition of MnO₂ on carbon fiber paper in mild acidic ZnSO₄+MnSO₄ electrolyte. Electrochemical and structural analysis identify that the MnO₂ cathode experience a consequent H⁺ and Zn²⁺ insertion/extraction process with high reversibility and cycling stability. To our best knowledge, it is the first report on rechargeable aqueous batteries with a consequent ion-insertion reaction mechanism