Preparation and characterization of B2S3-based chalcogenide glasses

The discovery of the fast ion conducting B[subscript]2S[subscript]3-based glasses has been one of the most significant development in the field of solid electrolytes. Considerable experimental studies have been done to maximize conductivities and chemical stabilities of these glass systems. Recently, the study of the structure and properties of these glasses compared to their oxide analog has become important;The IR spectra of M[subscript]2S + B[subscript]2S[subscript]3 (M = Li, K, Rb and Cs) and MS + B[subscript]2S[subscript]3 (M = Sr and Ba) thioborate glasses have shown the monotonic increase in tetrahedral boron units at the expense of thioboroxyl six-membered ring groups in a manner similar to that found in the alkali borate glasses in the low alkali glasses. Although the Li and K thioborate glasses were found to have structural similarities in the high alkali glasses, the Rb, Cs, Sr and Ba thioborate glasses have significant differences which arises from the fact that the alkali and alkaline earth ion plays a dominant role in controlling local structural environments;The density data and IR spectra for these glasses have shown the monotonic increase in tetrahedral boron units in the low alkali region, whereas the destruction of tetrahedral boron units arising from the formation of trigonal boron units with terminal non-bridging sulfurs for the high alkali glasses. In contrast to this behavior, the Tg measurements have shown the decreasing Tg with the addition of alkali modifier in the alkali thioborate glasses in the low alkali region. It is apparent that, although the SRO are similar in both systems, there are significant differences in the IRO and we have proposed that sulfur ions plays a dominant role in degrading IRO structure rather than enhancing

Improvements to the Overpotential of All-Solid-State Lithium-Ion Batteries during the Past Ten Years

After the research that shows that Li10GeP2S12 (LGPS)-type sulfide solid electrolytes can reach the high ionic conductivity at the room temperature, sulfide solid electrolytes have been intensively developed with regard to ionic conductivity and mechanical properties. As a result, an increasing volume of research has been conducted to employ all-solid-state lithium batteries in electric automobiles within the next five years. To achieve this goal, it is important to review the research over the past decade, and understand the requirements for future research necessary to realize the practical applications of all-solid-state lithium batteries. To date, research on all-solid-state lithium batteries has focused on achieving overpotential properties similar to those of conventional liquid-lithium-ion batteries by increasing the ionic conductivity of the solid electrolytes. However, the increase in the ionic conductivity should be accompanied by improvements of the electronic conductivity within the electrode to enable practical applications. This essay provides a critical overview of the recent progress and future research directions of the all-solid-state lithium batteries for practical applications

Stacked porous tin phosphate nanodisk anodes

Stacked porous octahedral tin phosphate Sn(2)P(2)O(7) nanodisks, with a thickness and a width of 20 nm and 200 nm, respectively, were prepared from quenching hydrothermally prepared (SnHPO(4))(2)center dot H(2)O at 600 degrees C. The first discharge capacity was 600 mA h g(-1) while the capacity retention, even after 220 cycles, was 93%.close7

Nanoparticle iron-phosphate anode material for Li-ion battery

Nanoparticle crystalline iron phosphates (FePO4.2H(2)O and FePO4) were synthesized using a (CTAB) surfactant as an anode material for Li rechargeable batteries. The electrochemical properties of the nanoparticle iron phosphates were characterized with a voltage window of 2.4-0 V. A variscite orthorhombic FePO4.2H(2)O showed a large initial charge capacity of 609 mAh/g. On the other hand, a tridymite triclinic FePO4 exhibited excellent cyclability: the capacity retention up to 30 cycles was similar to80%, from 485 to 375 mAh/g. The iron phosphate anodes exhibited the highest reported capacity, while the cathode LiFePO4 has an ideal capacity of 170 mAh/g.open515

Fully Conjugated Phthalocyanine Copper Metal-Organic Frameworks for Sodium-Iodine Batteries with Long-Time-Cycling Durability

Rechargeable sodium-iodine (Na-I-2) batteries are attracting growing attention for grid-scale energy storage due to their abundant resources, low cost, environmental friendliness, high theoretical capacity (211 mAh g(-1)), and excellent electrochemical reversibility. Nevertheless, the practical application of Na-I-2 batteries is severely hindered by their poor cycle stability owing to the serious dissolution of polyiodide in the electrolyte during charge/discharge processes. Herein, the atomic modulation of metal-bis(dihydroxy) species in a fully conjugated phthalocyanine copper metal-organic framework (MOF) for suppression of polyiodide dissolution toward long-time cycling Na-I-2 batteries is demonstrated. The Fe-2[(2,3,9,10,16,17,23,24-octahydroxy phthalocyaninato)Cu] MOF composited with I-2 (Fe-2-O-8-PcCu/I-2) serves as a cathode for a Na-I-2 battery exhibiting a stable specific capacity of 150 mAh g(-1) after 3200 cycles and outperforming the state-of-the-art cathodes for Na-I-2 batteries. Operando spectroelectrochemical and electrochemical kinetics analyses together with density functional theory calculations reveal that the square planar iron-bis(dihydroxy) (Fe-O-4) species in Fe-2-O-8-PcCu are responsible for the binding of polyiodide to restrain its dissolution into electrolyte. Besides the monovalent Na-I-2 batteries in organic electrolytes, the Fe-2-O-8-PcCu/I-2 cathode also operates stably in other metal-I-2 batteries like aqueous multivalent Zn-I-2 batteries. Thus, this work offers a new strategy for designing stable cathode materials toward high-performance metal-iodine batteries

High-Performance Heterostructured Cathodes for Lithium-Ion Batteries with a Ni-Rich Layered Oxide Core and a Li-Rich Layered Oxide Shell

The Ni-rich layered oxides with a Ni content of >0.5 are drawing much attention recently to increase the energy density of lithium-ion batteries. However, the Ni-rich layered oxides suffer from aggressive reaction of the cathode surface with the organic electrolyte at the higher operating voltages, resulting in consequent impedance rise and capacity fade. To overcome this difficulty, we present here a heterostructure composed of a Ni-rich LiNi0.7Co0.15Mn0.15O2 core and a Li-rich Li1.2-xNi0.2Mn0.6O2 shell, incorporating the advantageous features of the structural stability of the core and chemical stability of the shell. With a unique chemical treatment for the activation of the Li2MnO3 phase of the shell, a high capacity is realized with the Li-rich shell material. Aberration-corrected scanning transmission electron microscopy (STEM) provides direct evidence for the formation of surface Li-rich shell layer. As a result, the heterostructure exhibits a high capacity retention of 98% and a discharge- voltage retention of 97% during 100 cycles with a discharge capacity of 190 mA h g(-1) (at 2.0-4.5 V under C/3 rate, 1C = 200 mA g(-1)).ope

Efficient CO2 Utilization via a Hybrid Na-CO2 System Based on CO2 Dissolution

Carbon capture, utilization, and sequestration technologies have been extensively studied to utilize carbon dioxide (CO2), a greenhouse gas, as a resource. So far, however, effective technologies have not been proposed owing to the low efficiency conversion rate and high energy requirements. Here, we present a hybrid Na-CO2 cell that can continuously produce electrical energy and hydrogen through efficient CO2 conversion with stable operation for over 1,000 hr from spontaneous CO2 dissolution in aqueous solution. In addition, this system has the advantage of not regenerating CO2 during charging process, unlike aprotic metal-CO2 cells. This system could serve as a novel CO2 utilization technology and high-value-added electrical energy and hydrogen production device

High-Performance Direct Methanol Fuel Cells with Precious-Metal-Free Cathode

Direct methanol fuel cells (DMFCs) hold great promise for applications ranging from portable power for electronics to transportation. However, apart from the high costs, current Pt-based cathodes in DMFCs suffer significantly from performance loss due to severe methanol crossover from anode to cathode. The migrated methanol in cathodes tends to contaminate Pt active sites through yielding a mixed potential region resulting from oxygen reduction reaction and methanol oxidation reaction. Therefore, highly methanol-tolerant cathodes must be developed before DMFC technologies become viable. The newly developed reduced graphene oxide (rGO)-based Fe-N-C cathode exhibits high methanol tolerance and exceeds the performance of current Pt cathodes, as evidenced by both rotating disk electrode and DMFC tests. While the morphology of 2D rGO is largely preserved, the resulting Fe-N-rGO catalyst provides a more unique porous structure. DMFC tests with various methanol concentrations are systematically studied using the best performing Fe-N-rGO catalyst. At feed concentrations greater than 2.0 m, the obtained DMFC performance from the Fe-N-rGO cathode is found to start exceeding that of a Pt/C cathode. This work will open a new avenue to use nonprecious metal cathode for advanced DMFC technologies with increased performance and at significantly reduced cost.open0

High-Performance Direct Methanol Fuel Cells with Precious-Metal-Free Cathode

Direct methanol fuel cells (DMFCs) hold great promise for applications ranging from portable power for electronics to transportation. However, apart from the high costs, current Pt-based cathodes in DMFCs suffer significantly from performance loss due to severe methanol crossover from anode to cathode. The migrated methanol in cathodes tends to contaminate Pt active sites through yielding a mixed potential region resulting from oxygen reduction reaction and methanol oxidation reaction. Therefore, highly methanol-tolerant cathodes must be developed before DMFC technologies become viable. The newly developed reduced graphene oxide (rGO)-based Fe-N-C cathode exhibits high methanol tolerance and exceeds the performance of current Pt cathodes, as evidenced by both rotating disk electrode and DMFC tests. While the morphology of 2D rGO is largely preserved, the resulting Fe-N-rGO catalyst provides a more unique porous structure. DMFC tests with various methanol concentrations are systematically studied using the best performing Fe-N-rGO catalyst. At feed concentrations greater than 2.0 m, the obtained DMFC performance from the Fe-N-rGO cathode is found to start exceeding that of a Pt/C cathode. This work will open a new avenue to use nonprecious metal cathode for advanced DMFC technologies with increased performance and at significantly reduced cost.open0

Surface and Interfacial Chemistry in the Nickel-Rich Cathode Materials

With increasing demands for high energy lithium-ion batteries, layered nickel-rich cathode materials have been considered as the most promising candidate due to their high reversible capacity and low cost. Although some of the materials with nickel contents <= 60 % were commercialized, there are tremendous obstacles for further improvement of electrochemical performance, which is strongly related to the unstable cathode surface and interfacial properties. In this regard, a specific review on the interfacial chemistry between the cathode and electrolyte during electrochemical testing is provided. We highlight the underpinning interfacial chemistry and degradation mechanisms of the cathode materials. Finally, light is shed on the recent efforts for enhancing the interfacial stability of the nickel-rich cathode materials