A Single Potassium-Ion Conducting Metal–Organic Framework

Abstract

In this study, the 4-sulfobenzoic acid potassium salt is postsynthetically immobilized on the hexa-zirconium nodes of a zirconium-based MOF, MOF-808, by the solution-phase solvent-assisted ligand incorporation approach. With all of the sulfonate-based anions firmly immobilized within the rigid framework of MOF-808 along with mobile potassium ions present in the resulting material (MOF-808-SO3K), the MOF-808-SO3K-based solid-state electrolyte achieves an ionic conductivity of 3.1 × 10–5 S/cm at 303 K, a low activation energy of 0.32 eV, and a high transference number of 0.76 for potassium ions. The compound shows good long-term cycling stability with potassium metal during the charge–discharge processes. First-principles calculations are further performed to probe the structure of MOF-808-SO3K and gain insights into the ionic conduction of potassium ions in MOF-808-SO3K.

Zn-MOF-74-Derived Carbon Nanorods as an Efficient Se Host for K-Se Batteries

“…30,45 Whether at the potassiation or the depotassiation status, the K + diffusion coefficient value of Se@HCR is much higher than that of the Se/HCR mixture, indicating the superior K + diffusion kinetics of Se@HCR compared with the Se/HCR mixture (Figure 4f). 46 To elucidate the structure robustness of the Se@HCR electrode, morphology characterization is also conducted after cycling. The architecture of the Se@HCR nanorods remains almost the same as its original skeleton state, which is because of the stable chemical interaction between the carbon host and the selenium species (Figure 5a,b).…”

“…The constant current is set to be 20 mA g –1 for 10 min with a relaxation time of 20 min. As shown in Figure S14, the potassium diffusion coefficients can be obtained from Fick’s second law. , Whether at the potassiation or the depotassiation status, the K + diffusion coefficient value of Se@HCR is much higher than that of the Se/HCR mixture, indicating the superior K + diffusion kinetics of Se@HCR compared with the Se/HCR mixture (Figure f) …”

Sulfonate-Grafted Metal–Organic Framework─A Porous Alternative to Nafion for Electrochemical Sensors

“…49 After SALI, two additional peaks at 1200 and 1042 cm −1 corresponding to the S�O stretching can be clearly observed in the resulting spectrum, confirming the presence of sulfonate in SO 3 -MOF-808. 49 In addition, the negligible intensities of the FTIR peaks from C�O stretching vibration (1725 cm −1 ) and O−H bending vibration (900 cm −1 ) of the free carboxylic acid in the spectrum of SO 3 -MOF-808 also indicate the successful coordination of most sulfonate-based ligands on the hexa-zirconium nodes through the carboxylate group. 53 Zeta potentials of SO 3 -MOF-808 and MOF-808 measured in KCl aqueous solutions are −25.7 and −18.5 mV, respectively, suggesting the presence of more negatively charged moieties in the MOF after SALI.…”

“…In this study, a six-connected Zr-MOF, MOF-808, was served as a porous scaffold to postsynthetically immobilize the negatively charged sulfonate-based moieties via the solvent-assisted ligand incorporation (SALI) (Figure ). The installation of spatially dispersed sulfonate groups in Zr-MOFs by SALI has been demonstrated in our recent studies. , With the high density of sulfonate-based ligands present within the porous structure, the sulfonate-grafted MOF-808 (designated as SO 3 -MOF-808) was served as an “ion-gating membrane” to hinder the diffusion of negatively charged species (e.g., AA and UA) from the external solution to the underlying electrode surface of the partially reduced graphene oxide (GO)a well-known active material for electrochemical DA sensing. ,,, The current signals for DA detection as well as the selectivity against AA and UA of the SO 3 -MOF-808-modified electrode can outperform the conventional Nafion-coated electrode, suggesting that the porous sulfonate-grafted Zr-MOF can serve as the advanced alternative to Nafion for various electrochemical sensing applications.…”

Metal organic framework MOF-808-based solid-state electrolytes for lithium-ion batteries

“…[34][35][36][37] To further improve the transfer number (t + ) for lithium ions in MOFs, anionic species can be immobilized within the entire MOF framework along with mobile cations. [38][39][40] High-stability groups can also be grafted into MOFs to improve their electrochemical performance. 24,[41][42][43][44] Impregnating MOFs with ionic liquids has also shown potential as an SSE for LIBs.…”