Sulfurized Carbon Composite with Unprecedentedly High Tap Density for Sodium Storage

Abstract

excellent cycle life, and inexpensive active materials, the operation conditions (300-350 °C) for which the sodium metal is in liquid state should be reconsidered to ensure battery safety. [13][14][15] This constraint suggests the exploration of room-temperature (RT) Na-S batteries that undergo the formation of Na 2 S as the final product, with an energy density of 1274 Wh kg −1 , which is higher than that of the high-temperature Na-S batteries (760 Wh kg −1 ). [16,17] Similar to Li-S batteries, RT Na-S batteries suffer from problems such as poor cycling stability and self-discharge because of compatibility issues between the electrodes and electrolytes. [18,19] The high solubility of the polysulfide in the electrolyte formed during charging and discharging processes causes the polysulfide to migrate to the sodium-metal anode, namely "shuttle effect," resulting in its failure to return to the original sulfur and high-order polysulfide. [20][21][22][23] This phenomenon leads to the continuous loss of the sulfur active materials in the cathode as well as the active area of the sodium-metal anode, which negatively affects the cyclability and rate characteristics. Because the solid-electrolytic interphase (SEI) layer formed by the reaction of the sodium-metal anode and polysulfide is insulating, it directly reflects the battery characteristics. [24,25] Even worse, the volume expansion that occurs during the formation of the polysulfide causes disintegration of the sulfur electrode. [26][27][28] Efforts have been made to overcome the aforementioned drawbacks by investigating all of the battery components, including the cathodes, electrolytes, anodes, and separators. For cathodes, notable improvements have been made by modifying A novel sulfurized carbon decorated by terephthalic acid (TPA) and polyacrylonitrile (PAN), with unprecedently high tap density (≈1.02 g cm −3 ), is investigated. Room-temperature sodium-sulfur batteries offer high energy density; however, the dissolution of the polysulfide is a major factor hindering their commercialization. This dissolution problem can be tolerated by inhibiting the formation of polysulfide through binding sulfur to the carbon structure of PAN. Low sulfur content and low volumetric energy density in the composite are other drawbacks to be resolved. Heat-treated TPA induces a high-density carbonaceous material with high conductivity. This TPA is partly replaced by PAN, and the produced carbon and sulfur are composited with dehydrated polyacrylonitrile (CS-DPAN), which exhibits higher conductivity and surface area than the sulfurized dehydrated polyacrylonitrile (S-DPAN). The CS-DPAN composite electrode exhibits excellent electrochemical performance, and the resulting volumetric capacity is also superior to that of the S-DPAN material electrode. Operando Raman and operando X-ray diffraction analyses confirm that the increased capacity is realized via the avoidance of parasitic C 60 Na 3 formation formed below 1 V, by adjusting the operation voltage range. This finding demonstra...

Solvothermal Guided V2O5 Microspherical Nanoparticles Constructing High-Performance Aqueous Zinc-Ion Batteries

“…In general, larger internal voids and particle gaps in the cathode material result in a low tap density, which is a key parameter affecting the volumetric energy density of the electrode [23]. Low tap density results in low specific volume capacity because the electrodes are thicker for the same mass of loaded material, resulting in a longer charge transport path [24,25]. From a practical point of view, a high loading capacity and a dense ordered structure are effective ways to achieve cathodes with high volume specific capacity, and it is necessary to develop V 2 O 5 electrodes with high quality/volume-specific capacity without sacrificing cycle stability and multiplicity properties.…”