Synergistic Effect of the Anode Interface of Garnet-Type All-Solid-State Batteries

Next-generation lithium-ion batteries must have high energy density and safety, making the development of all-solid-state batteries imperative. One of the biggest advantages of an all-solid-state lithium-ion battery (ASSLIB) is that its alloy uses lithium metal as an anode while ignoring its flammability and other dangers. Herein, high-conductivity garnet-type Li6.75La3Zr1.75Ta0.25O12 (LLZTO) was chosen as the solid electrolyte part of an all-solid-state battery. A composite anode was formed by melting Li and MXene-MAX together, reducing the interface impedance from 566 to 55 Ω cm2. The Li-MXene|LLZTO|LFP full battery displayed a high initial discharge capacity of 163.0 mAh g–1 and a Coulombic efficiency of 97.0% and maintained 90.2% of its discharge capacity over 100 cycles, but it did not maintain a good overpotential. Therefore, the synergistic effect of Li-MXene-Pt will highly improve the performance of the full battery because of its high initial discharge capacity of 150.0 mAh g–1 and Coulombic efficiency of 95.5%, discharge capacity maintained at 93.3% over 100 cycles, and low overpotential of 0.04 V

Highly Stable Red Oxynitride β-SiAlON:Pr³⁺ Phosphor for Light-Emitting Diodes

Trivalent Pr3+-doped oxynitirde red phosphors β-SiAlON with composition Si6–zAlzOzN8–z:Prx (z = 0–2.0, x = 0.016) were synthesized by gas pressure sintering (GPS) at 1950 °C for 2 h. Red luminescence in the range 600–650 nm was detected upon excitation with 460 nm blue light, indicating that the phosphor can be excited by blue InGaN light-emitting diodes (LED). The crystallization and cell parameters of samples were investigated by powder X-ray diffraction (XRD), Rietveld refinement, and high-resolution transmission electron microscopy (HRTEM). Energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM) were further adopted to examine the effect of Al substitution on the microstructure. 27Al and 29Si solid-state nuclear magnetic resonance (NMR) data are consistent with SiN4–xOx and partially substituted AlN4–xOx tetrahedra. The temperature-dependent luminescence from the 1D2 and 3P0 states of Pr3+ were studied (10–573 K), and the integrated red emission from 600 to 650 nm increased with temperature (298–473 K). This unexpected phenomenon is proposed to be the result of two crossed excitation states in the configurational coordination diagram. This investigation reveals the superior characteristics of nitride compounds and the feasibility of doping Pr3+ into phosphor

Highly Efficient Photoelectrochemical Hydrogen Generation Reaction Using Tungsten Phosphosulfide Nanosheets

The initiation of hydrogen energy production from sunlight through photoelectrochemical (PEC) system is an important strategy for resolving contemporary issues in energy requirement. Although precious Pt and other noble metals offer a desirable catalytic activity for this method, earth-abundant nonprecious metal catalysts must be developed for wide-scale application. In this regard, P-type silicon (P-Si) micropyramids (Si MPs) are a favorable photocathode because of their effective light-conversion properties and appropriate band gap position. In this study, we developed amorphous tungsten phosphosulfide nanosheets (WS2–xPx NSs) on Si MPs through a simple thermal annealing process for solar-driven hydrogen evolution reaction. The P substitution in the nanostructure effectively produced many defective sites at the edges. The product exhibited an efficient photocurrent density of 19.11 mA cm–2 at 0 V and a low onset potential of 0.21 VRHE compared with tungsten disulfide (WS2; 13.43 mA cm–2). The fabricated catalyst also showed desirable stability for up to 8 h for the WS0.60P1.40@Si MPs photocathode. The extraordinary activity could be due to numerous active sites provided by heteroatoms (sulfur and phosphorus) in the edges, resulting in dwindling reaction kinetics barrier and enhanced PEC activity

In Situ and Low-Cost Improvement of the Lithium Anode Interface in Garnet-Type Solid-State Electrolytes

In recent years, the development of electric vehicles and environmental concerns have made necessary improvements in the energy density and safety of lithium-ion batteries. Therefore, the development of all-solid-state lithium-ion batteries (ASSLIBs) has become imperative. One advantage of ASSLIBs is their potential for downsizing with the use of lithium metal as the anode. However, in this study, a garnet-type solid electrolyte (Li6.75La3Zr1.75Ta0.25O12) was used, which has low reactivity with lithium metal. Thus, interface modification using CaCl2 was employed to form a Li–Ca–Cl composite anode. The interfacial resistance was remarkably reduced to 7 Ω cm2, and the symmetric cell exhibited stable cycling for 1200 h at room temperature and a current density of 0.1 mA cm–2. The voltage ranged from ±15 to ±16 mV. The full cell demonstrated a high initial discharge capacity of 149.2 mA h g–1 and a Coulombic efficiency of 98.0% while maintaining a discharge capacity retention of 91.3% after 100 cycles. These findings lay a solid foundation for future commercial applications as interface modification was achieved through a simple spin-coating process using low-cost CaCl2 (0.7 USD g–1)

Homogeneous Catalytic Process of a Heterogeneous Ru Catalyst in Li–O₂ via X‑ray Nanodiffraction Observation

In recent years, lithium oxygen batteries (Li–O2) have received considerable research attention due to their extremely high energy density. However, the poor conductivity and ion conductivity of the discharge product lithium peroxide (Li2O2) result in a high charging overpotential, poor cycling stability, and low charging rate. Therefore, studying and improving catalysts is a top priority. This study focuses on the commonly used heterogeneous catalyst ruthenium (Ru). The local distribution of this catalyst is controlled by using sputtering technology. Moreover, X-ray nanodiffraction is applied to observe the relationship between the decomposition of Li2O2 and the local distribution of Ru. Results show that Li2O2 decomposes homogeneously in liquid systems and heterogeneously in solid-state systems. This study finds that the catalytic effect of Ru is related to electrolyte decomposition and that its soluble byproducts act as electron acceptors or redox mediators, effectively reducing charging overpotential but also shortening the cycle life

In Situ and Low-Cost Improvement of the Lithium Anode Interface in Garnet-Type Solid-State Electrolytes

In recent years, the development of electric vehicles and environmental concerns have made necessary improvements in the energy density and safety of lithium-ion batteries. Therefore, the development of all-solid-state lithium-ion batteries (ASSLIBs) has become imperative. One advantage of ASSLIBs is their potential for downsizing with the use of lithium metal as the anode. However, in this study, a garnet-type solid electrolyte (Li6.75La3Zr1.75Ta0.25O12) was used, which has low reactivity with lithium metal. Thus, interface modification using CaCl2 was employed to form a Li–Ca–Cl composite anode. The interfacial resistance was remarkably reduced to 7 Ω cm2, and the symmetric cell exhibited stable cycling for 1200 h at room temperature and a current density of 0.1 mA cm–2. The voltage ranged from ±15 to ±16 mV. The full cell demonstrated a high initial discharge capacity of 149.2 mA h g–1 and a Coulombic efficiency of 98.0% while maintaining a discharge capacity retention of 91.3% after 100 cycles. These findings lay a solid foundation for future commercial applications as interface modification was achieved through a simple spin-coating process using low-cost CaCl2 (0.7 USD g–1)

High-Performance Lithium-Ion Battery and Symmetric Supercapacitors Based on FeCo₂O₄ Nanoflakes Electrodes

A successive preparation of FeCo₂O₄ nanoflakes arrays on nickel foam substrates is achieved by a simple hydrothermal synthesis method. After 170 cycles, a high capacity of 905 mAh g^–1 at 200 mA g^–1 current density and very good rate capabilities are obtained for lithium-ion battery because of the 2D porous structures of the nanoflakes arrays. The distinctive structural features provide the battery with excellent electrochemical performance. The symmetric supercapacitor on nonaqueous electrolyte demonstrates high specific capacitance of 433 F g^–1 at 0.1 A g^–1 and 16.7 F g^–1 at high scan rate of 5 V s^–1 and excellent cyclic performance of 2500 cycles of charge–discharge cycling at 2 A g^–1 current density, revealing excellent long-term cyclability of the electrode even under rapid charge–discharge conditions

Molybdenum Disulfide/Tin Disulfide Ultrathin Nanosheets as Cathodes for Sodium–Carbon Dioxide Batteries

Metal–CO2 rechargeable batteries are of great importance due to their higher energy density and carbon capture capability. In particular, Na–CO2 batteries are potential energy-storage devices that can replace Li-based batteries due to their lower cost and abundance. However, because of the slow electrochemical processes owing to the carbonated discharge products, the cell shows a high overpotential. The charge overpotential of the Na–CO2 battery increases because of the cathode catalyst’s inability to break down the insulating discharge product Na2CO3, thereby resulting in poor cycle performance. Herein, we develop an ultrathin nanosheet MoS2/SnS2 cathode composite catalyst for Na–CO2 battery application. Insertion of SnS2 reduces the overpotential and improves the cyclic stability compared to pristine MoS2. As shown by a cycle test with a restricted capacity of 500 mAh/g at 50 mA/g, the battery is stable up to 100 discharge–charge cycles as the prepared catalyst successfully decomposes Na2CO3. Furthermore, the battery with the MoS2/SnS2 cathode catalyst has a discharge capacity of 35 889 mAh/g. The reasons for improvements in the cycle performance and overpotential of the MoS2/SnS2 composite cathode catalyst are examined by a combination of Raman, X-ray photoelectron spectroscopy, and extended X-ray absorption fine structure analysis, which reveals an underneath phase transformation and changes in the local atomic environment to be responsible. SnS2 incorporation induces S-vacancies in the basal plane and 1T character in 2H MoS2. This combined impact of SnS2 incorporation results in undercoordinated Mo atoms. Such a change in the electronic structure and the phase of the MoS2/SnS2 composite cathode catalyst results in higher catalytic activity and reduces the cell overpotential

All-Solid-State Na–O₂ Batteries with Long Cycle Performance

All-solid-state sodium oxygen (ASS Na–O2) batteries have received interest due to their higher theoretical energy density, lower cost, higher safety level, and nonflammability compared with liquid electrolyte and Li–O2 batteries. Here, we report the application of carbon nanotube (CNT) and Ru/CNT cathodes, succinonitrile with a NaClO4 (SN + NaClO4) interlayer, a Na3Zr2Si2PO12 (NZSP) solid electrolyte, and a Na film anode for ASS Na–O2 batteries. Results showed that the SN + NaClO4 interlayer plays a crucial role in the tri-conductive cathode, ionic conductivity, and interfacial charge transfer kinetics between the Ru/CNT cathode and NZSP electrolyte. The ASS Na–O2 batteries with Ru/CNT and SN + NaClO4 tri-conductive cathodes exhibited a long cycling performance of 100 cycles (current density of 100 mA g–1 and limited capacity of 500 mA h g–1), a discharge capacity of 11 034 mA h g–1 (current density of 100 mA g–1), and a small overpotential gap of 1.4 V. These values were better than those for CNT and SN + NaClO4 tri-conductive cathodes (maximum discharge capacity of 2413 mA h g–1, 27 cycles, and potential gap of 1.7 V) with a Na2O2 discharge product. Ex situ analysis showed that the Ru/CNT cathode achieved superior reversibility deposition and decomposition of the Na2O2 discharge product. Therefore, the ASS Na–O2 battery system is safe and stable for energy storage applications

Fabrication of Nanorattles with Passive Shell

This investigation describes the formation of a metal nanorattle with a pure metal shell by varying experimental parameters. The galvanic replacement reaction between silver and chloroauric acid was adopted to prepare hollow metal nanoparticles. This approach is extended to produce nanorattles of Au cores and Au shells by starting with AucoreAgshell nanoparticles as templates. The effect of temperature on the nanostructure of the final product is also considered. The composition of the shell in nanorattles can be controlled by varying the reaction temperature (to form pure gold or gold−silver alloy, for example). X-ray absorption fine structure spectroscopy is conducted to elucidate the fine structure of these nanoparticles. Partial alloying between the Au core and the Ag shell is observed by extended X-ray absorption fine structure (EXAFS)