Superionic conduction along ordered hydroxyl networks in molecular-thin nanosheets

Abstract

Single-layer LDH nanosheets serve as a free hydroxide ion donor and 2D hopping lane for superionic conduction.

Layered double hydroxide membrane with high hydroxide conductivity and ion selectivity for energy storage device

“…The ions transport mechanism in LDHs. It was suggested by Sun et al that the Grotthuss mechanism was responsible for the fast hydroxyl ion conduction in LDHs by performing density functional theory (DFT) simulations 34,35 . However, it remains a challenge for the direct observation of the transport behavior of hydroxide in restricted interlayer gallery of LDHs under operating conditions, and thus confirming the conduction mechanism convincingly.…”

“…Combing with their well screened channel that can selectively separate different ions with different size and strong hydrogen bond network for hydroxide ions transport, LDHs are believed to ensure the membrane with proper ion selectivity as well as fast ions transport in alkaline environment, which is expected to break the trade-off between selectivity and permeation for a membrane and further enable a high-performance separation process. Although several groups have demonstrated high hydroxide ion (OH − ) conductivity of LDHs and explored the prospect of using LDHs in alkaline environment 34,35 , the deep-going studies of LDHs in the field of ions transport and the transport mechanism of OH − along ordered hydrogen-bonded nanostructures are very limited, which hindered the application of LDHs in ion separation field.…”

Recent Insights on Catalyst Layers for Anion Exchange Membrane Fuel Cells

“…[ 127 ] Recently, advanced designs for AEMs with high ion conductivities are emerging such as those having microporous structure, [ 128 ] introducing mobile ion shuttles, [ 129 ] enhancing hydrogen‐bond networks, [ 130 ] constructing charged 1D high‐order channels, [ 131 ] decreasing the distance between conductive groups, etc. [ 132 ] Theoretically, these AEM polymers have the potential to also be used as AEIs as solvent dispersions or powders. However, AEIs have specific requirements as compared with AEMs.…”

Efficient, scalable, closed-loop synthesis of highly crystalline pure phase MgAl-layered double hydroxides intercalated with hydroxyl anions

“…40,41 Besides, OH − ions in the interlayer galleries of MgAl-LDH are highly mobile and thus easily exchangeable with other anions. 42 Conventionally, the meixnerite form of LDH was prepared according to a "memory effect" 39,40 by first dehydrating at high temperature the pre-prepared LDH intercalated with CO 3 2− anions into a mixed metal oxide and then rehydrating the resulting oxide in water to reconstruct the LDH containing OH − ions. While our present method is more efficient and should produce MgAl-LDH with intercalated anions all being OH − in principle, this meixnerite form of LDH is vulnerable to contamination by atmospheric CO 2 , which would replace OH − ions in the form of carbonate.…”