Single-bubble sonoluminescence (SBSL) is achieved with strong stability in sulfuric acid solutions. Bubble dynamics and the SBSL spectroscopy in the sulfuric acid solutions with different concentrations are studied with phase-locked integral stroboscopic photography method and a spectrograph, respectively. The experimental results are compared with those in water. The SBSL in sulfuric acid is brighter than that in water. One of the most important reasons for that is the larger viscosity of sulfuric acid, which results in the larger ambient radius and thus the more contents of luminous material inside the bubble. However, sonoluminescence bubble’s collapse in sulfuric acid is less violent than that in water, and the corresponding blackbody radiation temperature of the SBSL in sulfuric acid is lower than that in water.
The Cover Feature shows the cogeneration of H2 and value-added formate from the electrolysis of methanol/water by a Ni–Co double hydroxide nanoneedle array bifunctional electrocatalyst obtained through a facile hydrothermal treatment. More information can be found in the Full Paper by M. Li et al. on page 914 in Issue 5, 2020 (DOI: 10.1002/cssc.201902921).
For Li-Se batteries, cathode using carbonaceous hosts to accommodate Se performed modestly, whereas those applying metallic compounds with stronger chemical adsorption exhibited even more rapid capacity decay, the intrinsic reasons for which are still not clear. Herein, it is found that Se tends to precipitate on the surface of the electrode during cycling, and the precipitation speed depends on the polarization degree of the host. A further enhanced adsorption does not certainly generate better electrochemical activity, since hosts with overhigh adsorption ability are hard to desorb polyselenides, leading to catalyst passivation and rapid capacity decay. These findings encourage us to design a ternary anatase/rutile/titanium nitride (aTiO2 /rTiO2 /TiN@C) composite host, integrating good adsorption of TiO2 and rapid electron transport ability of TiN, and introducing rutile to weaken overall adsorption. The aTiO2 /rTiO2 /TiN@C composite with medium adsorption not only avoids rapid loss of active substances in electrolyte but also slows down the precipitation speed of Se. As a result, the aTiO2 /rTiO2 /TiN@C/Se electrode delivered good rate capability(154 mA h g-1 at 20 C) and good cycling stability(a low decay of 0.024% per cycle within 500 cycles at 2 C).
Abstract Na metal anodes have attracted widespread attention due to their ultrahigh specific capacity, low redox potential as well as the huge abundance and ubiquitous distribution of sodium resources. However, the practical application of Na metal anodes is largely hindered by their poor cycling stability and safety issues, mainly caused by the uneven deposition and terrible dendrite growth of metallic Na. To regulate the Na deposition behavior and direct uniform plating, herein, a “gradient sodiophilic” carbon skeleton prompted by the difference in the disorder degree and defect concentration is proposed. These extraordinary features render the as‐proposed structure a promising accommodation for metallic Na, with a low nucleation overpotential of only 11.1 mV at 10 mA cm –2 and a small polarization voltage of 12 mV at 5 mA cm –2 in symmetric batteries. Impressively, the resultant structure reveals outstanding advantages in suppressing Na dendrites and thus enables a dendrite‐free Na metal anode. The findings gained in this work provide solutions to construct stable and dendrite‐free Na metal anodes through tailoring the Na deposition behavior.
Abstract Disordered carbons as the most promising anode materials for sodium ion batteries (SIBs) have attracted much attention, due to the widely‐distributed sources and potentially high output voltage when applied in full cells owing to the almost lowest voltage plateau. The complex microstructure makes the sodium storage mechanism of disordered carbons controversial. Recently, many studies show that the plateau region of disordered carbons are closely related to the embedment of sodium ion/semimetal in nanopores. In this regard, the classification, characterization and construction of nanopores are exhaustively discussed in this review. In addition, perspectives about the controllable construction of nanopores are presented in the last section, aiming to catch out more valuable studies include not only the construction of closed pores to enhance capacity but also the design of carbon materials to understand Na storage mechanism.
A P2/O3 Na0.62Ni0.33Mn0.62Sb0.05O2 composite cathode was synthesized which displays superior rate electrochemical performance compared with its monophasic counterpart Na0.67Ni0.33Mn0.67O2. P2–O2 phase transition is successfully suppressed and volume strain is extremely small during the electrochemical process.
Sodium dentrite formed by uneven plating/stripping can reduce the utilization of active sodium with poor cyclic stability and, more importantly, cause internal short circuit and lead to thermal runaway and fire. Therefore, sodium dendrites and their related problems seriously hinder the practical application of sodium metal batteries (SMBs). Herein, a design concept for the incorporation of metal–organic framework (MOF) in polymer matrix (polyvinylidene fluoride‐hexafluoropropylene) is practiced to prepare a novel gel polymer electrolyte (PH@MOF polymer‐based electrolyte [GPE]) and thus to achieve high‐performance SMBs. The addition of the MOF particles can not only reduce the movement hindrance of polymer chains to promote the transfer of Na + but also anchor anions by virtue of their negative charge to reduce polarization during electrochemical reaction. A stable cycling performance with tiny overpotential for over 800 h at a current density of 5 mA cm −2 with areal capacity of 5 mA h cm −2 is achieved by symmetric cells based on the resulted GPE while the Na 3 V 2 O 2 (PO 4 ) 2 F@rGO (NVOPF)|PH@MOF|Na cell also displays impressive specific cycling capacity (113.3 mA h g −1 at 1 C) and rate capability with considerable capacity retention.
Water/Methanol Coelectrolysis NiCo2S4 is developed through electrochemical deposition on carbon cloth, with the surface magnetism fine-tuned. The surface spin enhanced NiCo2S4 electrodes possess high stable bifunctional performance even in high current density in water/methanol coelectrolysis system. Hydrogen and value-added formate are harvested on both sides of the electrodes in the membrane-less cell, simultaneously, with energy saved. More details can be found in article number 2205257 by Xian-Zhu Fu, Jing-Li Luo, and co-workers.
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