The effect of hydration number on the interfacial transport of sodium ions

Peng, Jinbo; Cao, Duanyun; He, Zi; Guo, Jing; Hapala, Prokop; Ma, Runze; Cheng, Bowei; Chen, Ji; Xie, Wen Jun; Li, Xinzheng; Jelı́nek, Pavel; Xu, Limei; Gao, Yi Qin; Wang, Enge; Jiang, Ying

doi:10.1038/s41586-018-0122-2

Cited by 253 publications

(183 citation statements)

References 47 publications

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“…And it is likely that it is the abundance of the single H 2 O molecule that controls mineral dissolution, water transfer across cell walls, and across the air‐sea interface. The transport of ionic species across cell membranes is accompanied by associated water molecules in a modified solvation shell with remarkable increases in efficiency (Peng et al, ). Some of this is implicit in the way that temperature and pressure‐dependent formulae are written today, but the direct representation of the equilibrium state of water in natural waters appears to be a more natural and teachable approach.…”

Section: Discussionmentioning

confidence: 99%

How Much H₂O Is There in the Ocean? The Structure of Water in Sea Water

2019

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We report on laboratory and field Raman spectroscopy experiments on the structure of water in sea water and describe this as a function of temperature and pressure. The Raman spectrum of water/seawater is dominated by the water stretching mode band with a frequency shift in the range 2,800-3,800 cm À1 . Here the hydrogen bonded (HB) clusters of several water molecules and nonhydrogen bonded (nHB, singlet H 2 O) forms are revealed with an isoskedastic point, similar to the isosbestic point for pH sensitive dyes. This band can be deconvolved into five Gaussian peaks, each with a specific spectroscopic assignment. We find that within the temperature range of 0-40°C the vastly greater mass and volume of ocean water (78-85%) is in the HB forms, dominantly as (H 2 O) 5 . Without hydrogen bonding there would be no ocean, and nowhere in the bulk ocean does the simple H 2 O molecule exceed 20% of the total. The fraction of water molecules in the solvation shell around ions in seawater represents a third type of water, bound to an ion but not hydrogen bonded. Approximately 6% of the water molecules present at 35 salinity are in this form, and their concentration is not affected by temperature or pressure. The HB forms are a continuum of species in rapid exchange. The fraction of nHB is driven solely by temperature. We find no evidence that increased pressure changes the population of the free singlet nHB molecule; pressure drives the dominantly (H 2 O) 5 population toward a lower volume, nested, molecular state. Plain Language SummaryFor over 50 years ocean scientists have represented the important physical properties of sea water as a collection of bulk fluid coefficients that simply provided a statistical fit to the observed compressibility, sound speed, etc.-but with no underlying molecular basis. Sea water is 96.5% water, and for over 50 years chemists describing the molecular physics of pure water have evolved an understanding that water is composed of a temperature-driven balance between the hydrogen bonded and nonhydrogen bonded forms, but this knowledge has not been applied to the oceans-the largest body of water on Earth. Here we link these two fields by using laser Raman spectroscopy. We show that by far the greater volume of the ocean-some 78-85% is composed of the hydrogen bonded form (H 2 O) 5 . Without this water would not be liquid and we would literally have no ocean at all. With this knowledge we are better able to understand the processes occurring under climate-driven ocean warming.Here we briefly review this body of knowledge, and we report on both laboratory and field spectroscopic experiments to test how well the knowledge of hydrogen bonding in pure water can be translated into the medium of sea water. We describe the chemical structures that underlie the physical properties of sea water and assess their abundance in the ocean water column.In simplest terms, the structure of water is the result of the balance between the thermal forces pulling water clusters apart and the chemical forces holding thes...

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Section: Discussionmentioning

confidence: 99%

How Much H₂O Is There in the Ocean? The Structure of Water in Sea Water

2019

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“…This process is distinctive from the electrochemical potassiation process, where new thermodynamic phases (such as the s-KBir/h-KBir samples here) are produced after the potassiation and then they could be employed as the initial structure for subsequent electrochemical tests. [35] Nevertheless, the mechanism of interlayer H 2 O contributing to the electrochemical performance begs for further detailed investigation, which is beyond the scope of this study. In addition, the interlayer H 2 O could facilitate the ion diffusion based on the specific hydration-number effect.…”

Section: Potassium Storage Chemistrymentioning

confidence: 95%

K‐Birnessite Electrode Obtained by Ion Exchange for Potassium‐Ion Batteries: Insight into the Concerted Ionic Diffusion and K Storage Mechanism

Gao

Guo

et al. 2018

Advanced Energy Materials

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kind of secondary batteries will find promising applications in large-scale energy storage. [3] Owing to the low-cost [4] and low standard potential [5] of potassium (K), KIBs could in principle offer cost-effectiveness and higher energy density, which would lead to a substantial advance in energy storage technology. The fast K + ion diffusion property provides the possibility of saving the charging time of KIBs as the next generation energy storage and transport devices. [6] Then compared with Na-ion battery (NIB), a huge advantage lies in the application of graphite anode for KIB, [7] which is not feasible for Na + insertion into the graphite. [8] And also, the weaker Lewis acidity of K + ions ensures smaller solvated ions, leading to the higher mobility and larger transference number in electrolytes and lower desolvation energy, which offers faster K + ion diffusion kinetics with regard to that of Li + or Na + ions. [4,9] Based on these advantages, many investigations on the available anode materials for KIBs, such as carbonaceous materials, [8a,10] oxides, [11] sulfides, [12] organic materials, [13] alloy, [5] prussian blue analogues, [14] etc., have been reported continuously in the past few decades, [2a,15] however, fewer studies are devoted to the development of cathode. Present cathodes could be summarized as the layered transition metal oxides, [16] polyanions and pyrophosphates, [17] prussian blue analogs, [18] nanostructured iron composite, [19] organic materials, [20] and other potential materials. Up to now, most of the available studies are working on screening for new electrode materials with enhanced electrochemical performance, while the underlying K storage and transport mechanism in the electrode materials is lack of exploration and comprehension. [2a,21] Therefore, studying the electrochemical behavior of potassium ions is very important for building a better KIBs system.In specific, alkali transition metal oxides (AMO 2 : A = Li, Na, K; M = Ni, Co, Mn, Fe, etc.) with layered structure have been widely studied as promising cathodes for rechargeable batteries, [22] because of the topotactic de/intercalation feature. However, the accommodation of the bulky K + ion is less favorable than that of Li + and Na + ion in such compact structures, [2a] which will plausibly hinder the K + ion diffusion kinetics. [23] Previous reports [16e,24] have shown the sluggish diffusion performance of K + ions in KIBs with alkali transition Novel and low-cost rechargeable batteries are of considerable interest for application in large-scale energy storage systems. In this context, K-Birnessite is synthesized using a facile solid-state reaction as a promising cathode for potassium-ion batteries. During synthesis, an ion exchange protocol is applied to increase K content in the K-Birnessite electrode, which results in a reversible capacity as high as 125 mAh g −1 at 0.2 C. Upon K + exchange the reversible phase transitions are verified by in situ X-ray diffraction (XRD) characterization. The underlying mechani...

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“…Owing to the confinement effect, the hydration shell of an ion must rearrange itself to fit the surrounding environment, which usually results in the constriction of the hydration shell . This phenomenon, termed as ion dehydration, is closely associated with many practical processes including drug delivery, capacitive mixing technology, water purification, supercapacitor, and interfacial transport …”

Section: Introductionmentioning

confidence: 99%