High ionic conductivity of Mg–Al layered double hydroxides at intermediate temperature (100–200°C) under saturated humidity condition (100% RH)

Layered Double Hydroxides Containing an Ionic Liquid: Ionic Conductivity and Use in Composite Anion Exchange Membranes

“…[27][28] To this end, it should be noted that the LDH anion conductivity can be modulated incorporating different anions in the interlayer allowing their use as solid electrolytes or as fillers in different electrochemical applications, such as fuel cells, sensors, electrocatalysts and supercapacitors. [35] In particular, we have verified that, in agreement with the results of previous literature, [36][37][38] the measured values of conductivity are strongly dependent on the humidity; at 100 % relativity humidity (RH) they are between 3.4 10 À5 S cm À1 for NO 3 À and 7.1 10 À5 S cm À1 for F À LDHs. [35] In particular, we have verified that, in agreement with the results of previous literature, [36][37][38] the measured values of conductivity are strongly dependent on the humidity; at 100 % relativity humidity (RH) they are between 3.4 10 À5 S cm À1 for NO 3 À and 7.1 10 À5 S cm À1 for F À LDHs.…”

“…[35] In particular, we have verified that, in agreement with the results of previous literature, [36][37][38] the measured values of conductivity are strongly dependent on the humidity; at 100 % relativity humidity (RH) they are between 3.4 10 À5 S cm À1 for NO 3 À and 7.1 10 À5 S cm À1 for F À LDHs. [36][37][38] Furthermore, a decrease of the humidity dependence is a challenge for many solid electrolytes; in the case of fuel cells, the low ionic conductivity at low humidity is a serious drawback and an external humidifier is necessary to ensure the required humidification. [36] Such results suggest that the anion conduction occurs primarily in the interlayer space and the adsorbed water assists the anion conduction.…”

Hydroxide Ion Conducting Antimony(V)‐Doped Tin Pyrophosphate Electrolyte for Intermediate‐Temperature Alkaline Fuel Cells

“…Additional benefits include small polarization loss, good drainage at the anode, and effective heat dissipation from the fuel cell system. A few anion‐conducting electrolyte materials capable of operating at intermediate temperatures (100–200 °C) have been reported, such as KOH‐doped polybenzimidazole (PBI)6 and hydroxide ion‐intercalated Mg–Al layered double hydroxide (LDH) 7. However, the reaction of KOH in the former electrolyte with CO 2 present in the air to form K 2 CO 3 is a possibility, and the hydroxide ion conductivity of the latter (0.03 S cm −1 at 200 °C) is not sufficiently high to achieve satisfactory cell performance.…”

Preparation of hydroxide ion conductive KOH–layered double hydroxide electrolytes for an all-solid-state iron–air secondary battery

“…The temperature dependence of all pellets is not of the Arrhenius type but of the Vogel-Tamman-Fulcher (VTF) type. Water in the interlayer and on the surface of the layered LDH materials contributes to the mechanism of hydroxide ion conduction [19,20]. Such a strong temperature dependence of the conductivity suggests that hydroxide ions are transferred through the liquid-like phase of the LDH structures filled with water molecules.…”

“…Solidification of the electrolyte is one of the effective means to enhance the reliability of the batteries from several drawbacks like the volume change by leakage and freeze of liquids [10,16]. Layered double hydroxides (LDHs) are interesting materials for use as hydroxide ion conductors owing to their layered structure intercalated with anions and water molecules [17][18][19][20]. In this study, we report the hydroxide ion conductivities of solid electrolytes based on Mg-Al LDH with the addition of KOH.…”