Iron-based Prussian blue analogs are promising low-cost and easily prepared cathode materials for sodium-ion batteries. Their materials quality and electrochemical performance are heavily reliant on ...the precipitation process. Here we report a controllable precipitation method to synthesize high-performance Prussian blue for sodium-ion storage. Characterization of the nucleation and evolution processes of the highly crystalline Prussian blue microcubes reveals a rhombohedral structure that exhibits high initial Coulombic efficiency, excellent rate performance, and cycling properties. The phase transitions in the as-obtained material are investigated by synchrotron in situ powder X-ray diffraction, which shows highly reversible structural transformations between rhombohedral, cubic, and tetragonal structures upon sodium-ion (de)intercalations. Moreover, the Prussian blue material from a large-scale synthesis process shows stable cycling performance in a pouch full cell over 1000 times. We believe that this work could pave the way for the real application of Prussian blue materials in sodium-ion batteries.
Prussian blue analogs (PBAs) are promising cathode materials for sodium‐ion batteries (SIBs) due to their low‐cost, similar energy density comparable with that of LiFePO4 in lithium‐ion batteries, ...and long cycle life. Nevertheless, crystal water (≈10 wt%) in PBAs from aqueous synthesis environments can bring significant side effects in real SIBs, especially for calendar life and high temperature storage performance. Therefore, it is of great importance to eliminate crystal water in PBAs for future commercial applications. Herein, a facile heat‐treatment method is reported in order to remove water from Fe‐based PBAs. Although the heat‐treated sample can be easily rehydrated in air, it still exhibits a stable cycling performance over 2000 times under controlled charge cut‐off voltage. In situ synchrotron high‐temperature powder X‐ray diffraction demonstrates that the as‐prepared sample is maintained at a new trigonal phase after dehydration. Moreover, the redox reaction of low‐spin Fe2+/Fe3+ is activated and the high‐temperature storage performance of as‐prepared sample is significantly improved after removal of water.
Heat‐treated Prussian blue cathode material with kilograms yield are fabricated by a facile precipitation method, which demonstrates the potential to realize real application of low‐cost Prussian blue analogs for sodium‐ion batteries. The as‐obtained material demonstrates a stable trigonal phase with outstanding performance in both coin cells and pouch full cells.
In order to provide an efficient tool to explore alloy composition and processing conditions for Mg-based alloys with good hydriding/dehydriding (H/D) properties, investigation of the Mg-Ni-Nd-H ...quaternary system was carried out by experimental measurements and CALPHAD thermodynamic analysis combined with first-principles calculations. A new stable compound Nd16Mg96Ni12 with the space group of Cmc21 was identified in the Mg-Ni-Nd system by synchrotron powder X-ray diffraction (SR-PXRD). The phase equilibria and phase transformation related to Nd4Mg80Ni8, Nd16Mg96Ni12, NdMg5Ni and NdMg2Ni were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The formation enthalpies of these ternary compounds were calculated by the density functional theory. The existence of the quaternary hydrides NdMgNi4H4 and NdMg2Ni9H12 was taken into consideration. Based on the obtained thermodynamic description of the Mg-Ni-Nd-H system, the hydrogen storage capacities and pressure-composition-temperature (P-C-T) curves were predicted and two new ternary compounds Nd4Mg80Ni8 and Nd16Mg96Ni12 were designed as hydrogen storage alloys with excellent properties. Meanwhile, the H/D mechanism of the Mg-Ni-Nd alloy was revealed.
Abstract
K‐metal batteries have become one of the promising candidates for the large‐scale energy storage owing to the virtually inexhaustible and widely potassium resources. The uneven K
+
...deposition and dendrite growth on the anode causes the batteries prematurely failure to limit the further application. An integrated K‐metal anode is constructed by cold‐rolling K metal with a potassiphilic porous interconnected mediator. Based on the experimental results and theoretical calculations, it demonstrates that the potassiphilic porous interconnected mediator boosts the mass transportation of K‐metal anode by the K affinity enhancement, which decreases the concentration polarization and makes a dendrite‐free K‐metal anode interface. The interconnected porous structure mitigates the internal stress generated during repetitive deposition/stripping, enabling minimized the generation of electrode collapse. As a result, a durable K‐metal anode with excellent cycling ability of exceed 1, 000 h at 1 mA cm
−2
/1 mAh cm
−2
and lower polarization voltage in carbonate electrolyte is obtained. This proposed integrated anode with fast K
+
kinetics fabricated by a repeated cold rolling and folding process provides a new avenue for constructing a high‐performance dendrites‐free anode for K‐metal batteries.
Room‐temperature sodium–sulfur (RT Na–S) batteries have attracted extensive attention because of their low cost and high specific energy. RT Na–S batteries, however, usually suffer from sluggish ...reaction kinetics, low reversible capacity, and short lifespans. Herein, it is shown that chain‐mail catalysts, consisting of porous nitrogen doped carbon nanofibers (PCNFs) encapsulating Co nanoparticles (Co@PCNFs), can activate sulfur via electron engineering. The chain‐mail catalysts Co@PCNFs with a micrograde hierarchical structure as a freestanding sulfur cathode (Co@PCNFs/S) can provide space for high mass loading of sulfur and polysulfides. The electrons can rapidly transfer from chain‐mail catalysts to sulfur and polysulfides during discharge–charge processes, therefore boosting its conversion kinetics. As a result, this freestanding Co@PCNFs/S cathode achieves a high sulfur loading of 2.1 ± 0.2 mg cm−2, delivering a high reversible capacity of 398 mA h g−1 at 0.5 C (1 C = 1675 mA g−1) over 600 cycles and superior rate capability of an average capacity of 240 mA h g−1 at 5 C. Experimental results, combined with density functional theory calculations, demonstrate that the Co@PCNFs/S can efficiently improve the conversion kinetics between the polysulfides and Na2S via transferring electrons from Co to them, thereby realizing efficient sulfur redox reactions.
A chain‐mail catalyst consisting of porous nitrogen doped carbon nanofibers (PCNFs) encapsulating Co nanoparticles is developed for a freestanding sulfur cathode (Co@PCNFs/S) in room‐temperature sodium–sulfur batteries. The electron engineering in Co@PCNFs/S can transfer electrons from Co@PCNFs to sulfur and polysulfides, which activates reactivity and the conversion kinetics of the S cathode, leading to long cycling stability and high‐rate capacity.
Efficient removal of particulate matter (PM) is the major goal for various air cleaning technologies due to its huge impact on human health. Here, a washable high‐efficiency triboelectric air filter ...(TAF) that can be used multiple times is presented. The TAF consists of five layers of the polytetrafluoroethylene (PTFE) and nylon fabrics. Compared with traditional electrostatic precipitator, which requires a high‐voltage power supply, the TAF can be charged by simply rubbing the PTFE and nylon fabrics against each other. The electrical properties of the TAF are evaluated through the periodic contacting–separating of the PTFE and nylon fabrics using a linear motor, and an open‐circuit voltage of 190 V is achieved. After charging, the TAF has a removal efficiency of 84.7% for PM0.5, 96.0% for PM2.5, which are 3.22 and 1.39 times as large as the uncharged one. Most importantly, after washing several times, the removal efficiency of the TAF maintains almost the same, while the commercial face mask drops to 70% of its original efficiency. Furthermore, the removal efficiency of the PM2.5 is very stable under high relative humidity. Therefore, the TAF is promising for fabricating a reusable and high‐efficiency face mask.
A multilayer triboelectric air filter consists of five layers of polytetrafluoroethylene (PTFE) and nylon fabrics. A high removal efficiency is achieved by rubbing the fabrics against each other, and the removal efficiency maintains high under high humidity, in a durability test or after several washing cycles. Moreover, a face mask made of this air filter can be used in daily life.
The low-cost room-temperature sodium-sulfur battery system is arousing extensive interest owing to its promise for large-scale applications. Although significant efforts have been made, resolving low ...sulfur reaction activity and severe polysulfide dissolution remains challenging. Here, a sulfur host comprised of atomic cobalt-decorated hollow carbon nanospheres is synthesized to enhance sulfur reactivity and to electrocatalytically reduce polysulfide into the final product, sodium sulfide. The constructed sulfur cathode delivers an initial reversible capacity of 1081 mA h g
with 64.7% sulfur utilization rate; significantly, the cell retained a high reversible capacity of 508 mA h g
at 100 mA g
after 600 cycles. An excellent rate capability is achieved with an average capacity of 220.3 mA h g
at the high current density of 5 A g
. Moreover, the electrocatalytic effects of atomic cobalt are clearly evidenced by operando Raman spectroscopy, synchrotron X-ray diffraction, and density functional theory.
Blue hydrogenated rutile TiO2 nanoparticles (blue TiO2) are prepared by treating white rutile via an enhanced hydrogenation process (i.e., high pressure and temperature). The materials ...characterization results demonstrate that the hydrogenation process leads to the increase in the unit cell volume and decrease in the size compared with the untreated white TiO2. The electrochemical impedance spectra analyses and theoretical energy calculations using density functional theory (DFT) suggest that the hydrogenation process not only improves electronic conductivity due to the formation of oxygen vacancy in the hydrogenation process but also dramatically augments lithium-ion mass transport within the crystalline lattice due to the introduction of oxygen vacancy and crystalline dislocation. Because of these characteristics resulting from the hydrogenation process, the blue TiO2 based lithium ion batteries (LIBs) possess significantly higher energy capacity and better rate performance than the white TiO2 based LIBs. In particular, at the rate of 0.1 and 5 C (1 C = 336 mAh g–1), the discharge capacities of the blue rutile are maintained at ca.179.8 and 129.2 mAh g–1, while the capacities of the white TiO2 are just ca. 119.6 and 55.5 mAh g–1, respectively.
Despite the high theoretical capacity of the sodium–sulfur battery, its application is seriously restrained by the challenges due to its low sulfur electroactivity and accelerated shuttle effect, ...which lead to low accessible capacity and fast decay. Herein, an elaborate carbon framework, interconnected mesoporous hollow carbon nanospheres, is reported as an effective sulfur host to achieve excellent electrochemical performance. Based on in situ synchrotron X-ray diffraction, the mechanism of the room temperature Na/S battery is proposed to be reversible reactions between S8 and Na2S4, corresponding to a theoretical capacity of 418 mAh g–1. The cell is capable of achieving high capacity retention of ∼88.8% over 200 cycles, and superior rate capability with reversible capacity of ∼390 and 127 mAh g–1 at 0.1 and 5 A g–1, respectively.
Volatile organic compounds (VOCs) produced by various bacteria have significant potential to enhance plant growth and to control phytopathogens. Six of the most effective antagonistic Bacillus spp. ...were used in this study against Ralstonia solanacearum (Rsc) TBBS1, the causal agent of bacterial wilt disease in tobacco. Bacillus amyloliquefaciens FZB42 and Bacillus artrophaeus LSSC22 had the strongest inhibitory effect against Rsc. Thirteen VOCs produced by FZB42 and 10 by LSSC22 were identified using gas chromatography-mass spectrometry analysis. Benzaldehyde, 1,2-benzisothiazol-3(2 H)-one and 1,3-butadiene significantly inhibited the colony size, cell viability, and motility of pathogens and negatively influenced chemotaxis. Transmission and scanning electron microscopy revealed severe morphological and ultra-structural changes in cells of Rsc. Furthermore, VOCs altered the transcriptional expression level of PhcA (a global virulence regulator), type III secretion system (T3SS), type IV secretion system (T4SS), extracellular polysaccharides and chemotaxis-related genes, which are major contributors to pathogenicity, resulting in decreased wilt disease. The VOCs significantly up-regulated the expression of genes related to wilt resistance and pathogen defense. Over-expression of EDS1 and NPR1 suggest the involvement of SA pathway in induction of systemic resistance. Our findings provide new insights regarding the potential of antibacterial VOCs as a biocontrol tool against bacterial wilt diseases.
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