Tailoring Electronic Structure and Size of Ultrastable Metalated Metal–Organic Frameworks with Enhanced Electroconductivity for High‐Performance Supercapacitors

Abstract

Utilization of metal-organic frameworks (MOFs) as electrodes for energy storage/conversion is challenging because of the low chemical stability and poor electrical conductivity of MOFs in electrolytes.Ananoscale MOF, Co 0.24 Ni 0.76 -bpa-200, possessing ultrahigh stability with uncommon semiconductor behavior (s = 4.2 10 À3 Sm À1 )w as fabricated. The MOF comprises ar obust hydrophobic paddlewheel and an optimized Co/Ni ratio,with consequent control over MOF size and the degree of conjugation of the coligand. AD FT study revealed that appropriate Ni 2+ doping reduces the activation energy of the system, thus providing ah igher carrier concentration, and the strongly delocalized N-donor ligand notably increases the metal-ligand orbital overlap to achieve efficient charge migration, leading to continuous through-bond (-CoNi-N-CoNi-) 1 conduction paths.These structural features endow the MOF with agood cycling stability of 86.5 %(10 000 cycles) and ahigh specific capacitance of 1927.14 Fg À1 among pristine MOF-based electrodes.

Novel Electrode Materials and Redox‐Active Electrolyte for High‐Performance Supercapacitor

“…The specific capacitance of the working electrode (C s , F g À 1 ) in the three-electrode system in a 1 m H 2 SO 4 solution was evaluated from the discharge curve in GCD using Equation (5). 36] C S ¼ I Dt=ðm DVÞ (5) The specific capacity of the working electrode (Q s , mAh g À 1 ) in the three-electrode system in a KIÀ H 2 SO 4 electrolyte was evaluated from the discharge curve in GCD using Equation (6).…”

“…A tremendous amount of research on how to increase their energy density have thus been conducted. [6][7] The introduction of redox capacity is an effective strategy to increase the specific capacitance of supercapacitors. [8] Doping redox active materials in carbon materials allows the composite materials to undergo a reversible Faradaic electrochemical reaction, resulting in additional capacity.…”

Recent advances in pillar‐layered metal‐organic frameworks with interpenetrated and non‐interpenetrated topologies as supercapacitor electrodes

“…The introduction of hydrophobic paddle‐wheel SBUs can effectively avoid the attack of water molecules and hydroxide ions and therefore could be beneficial to electron transport [55] . In this regard, the multi‐carboxylate‐containing ligands were also documented to construct the hydrophobic and the paddle‐wheel‐like SBUs [56] . In 2021, Xia et al [56] .…”

“…In this regard, the multi‐carboxylate‐containing ligands were also documented to construct the hydrophobic and the paddle‐wheel‐like SBUs [56] . In 2021, Xia et al [56] . chose the hydrophobic H 2 camph (DL‐(±)‐camphoric acid) to connect distinct Co‐bpy or Co‐bpe motifs together to form 3D non‐interpenetrating pillar‐layered frameworks (bpa=1,2‐di(pyridin‐4‐yl)ethyne; bpy=4,4’‐bipyridine).…”

Metal–Organic Frameworks Constructed from Iron‐Series Elements for Supercapacitors

“…Notably, according to this strategy of documenting π ‐conjugated molecules, Xia et al adopted conjugated pillar ligands to co‐construct the conductive pillar‐layered MOFs systems, the achieved M‐MOFs (M = Co and Ni) could also display good capacitance retention of 86.5% after continuous 10 000 cycles and a maximum gravimetric capacitance of 1927.14 F g −1 (Figure 5d). [ 160 ] Apart from the good performances, this work provides a new strategy to construct highly conductive pillar‐layered MOFs reservoirs for the future because Bi and co‐workers found that the 3D conductive MOF‐based family could be expected to have advantages over the 2D MOF layers with quasi‐1D pores due to the dense stacks of 2D motifs. [ 161 ] Therefore, combining the strategy of designing 2D conductive MOFs with constructing pillar‐layered MOFs could be an optimal choice for future researchers.…”