Confined Interlayer Water Promotes Structural Stability for High-Rate Electrochemical Proton Intercalation in Tungsten Oxide Hydrates

Abstract

There is widespread interest in determining the structural features of redox-active electrochemical energy storage materials that enable simultaneous high power and high energy density. Here, we present the discovery that confined interlayer water in crystalline tungsten oxide hydrates, WO3·nH2O, enables highly reversible proton intercalation at subsecond time scales. By comparing the structural transformation kinetics and confined water dynamics of the hydrates with anhydrous WO3, we determine that the rapid electrochemical proton intercalation is due to the ability of the confined water layers to isolate structural transformations to two dimensions while stabilizing the structure along the third dimension. As a result, these water layers provide both structural flexibility and stability to accommodate intercalation-driven bonding changes. This provides an alternative explanation for the fast energy storage kinetics of materials that incorporate structural water and provides a new strategy for enabling high power and high energy density with redox-active layered materials containing confined fluids.

Porous Metal–Organic Frameworks Containing Reversible Disulfide Linkages as Cathode Materials for Lithium‐Ion Batteries

“…To sum up, XAFS analyses confirmed the occurrence of dual redox reactions of metal ions and disulfide moieties in 1 D‐DS‐Co‐MOF, 2 D‐DS‐Cu‐MOF, and 3 D‐DS‐Mn‐MOF during charge/discharge, which resulted in high, close‐to‐theoretical capacities, although there is a possibility that water molecules remaining in MOFs contribute to the capacities as reported recently in the literature . Furthermore, the cycling performance stability was attributed to the presence of electrochemically dynamic S−S bonds in the porous DS‐MOFs.…”

Effect of Hydration on the Molecular Dynamics of Hydroxychloroquine Sulfate

“…While the upper panels of Figures 10 and 11 show the measured spectra, the lower panels present a comparison of the difference spectra between the main hydrated and dry HCQS samples to the spectra of H 2 O ice-Ih (5 K) and liquid water (295 K) as well as the structural H 2 O in WO 3 ·H 2 O data. 29 In Figure 10 , the peaks at ∼372 meV are mainly due to C–H and N–H stretching modes, and the shoulder at ∼420 meV in the main hydrated HCQS sample spectra is due to O–H stretching modes of the hydration water (this peak is prominent in the difference spectrum at 6 K). At 6 K, the peak at ∼372 meV can be fitted with two Gaussians, centered at 369 and 380 meV for the dry HCQS sample and 369 and 376 meV for the main hydrated HCQS sample.…”

Phase transformation in tungsten oxide nanoplates as a function of post-annealing temperature and its electrochemical influence on energy storage

“…24 Recently, Mitchell reported the monoclinic WO 3 $2H 2 O, orthorhombic WO 3 $H 2 O, and monoclinic g-WO 3 structure at room temperature, 120 C and 350 C, respectively. 25 The g-WO 3 structure demonstrated the highest capacity of 420 C g À1 as compared to the monoclinic WO 3 $2H 2 O (360 C g À1 ) and orthorhombic WO 3 $H 2 O (386 C g À1 ). Augustyn et al observed threefold increments in the capacitance of g-WO 3 (227 F g À1 ) as compared to monoclinic WO 3 $2H 2 O (75 F g À1 ).…”