Metal-organic frameworks and their derived materials for electrochemical energy storage and conversion: Promises and challenges

Abstract

In addition to their conventional uses, metal-organic frameworks (MOFs) have recently emerged as an interesting class of functional materials and precursors of inorganic materials for electrochemical energy storage and conversion technologies. This class of MOF-related materials can be broadly categorized into two groups: pristine MOF-based materials and MOF-derived functional materials. Although the diversity in composition and structure leads to diverse and tunable functionalities of MOF-based materials, it appears that much more effort in this emerging field is devoted to synthesizing MOF-derived materials for electrochemical applications. This is in view of two main drawbacks of MOF-based materials: the low conductivity nature and the stability issue. On the contrary, MOF-derived synthesis strategies have substantial advantages in controlling the composition and structure of MOF-derived materials. From this perspective, we review some emerging applications of both groups of MOF-related materials as electrode materials for rechargeable batteries and electrochemical capacitors, efficient electrocatalysts, and even electrolytes for electrochemical devices. By highlighting the advantages and challenges of each class of materials for different applications, we hope to shed some light on the future development of this highly exciting area.

Fig. 1. Schematic of MOF-related materials for renewable energy.

MOF-based materials with different functionalities by tuning the constituent components: (left to right) electrochemical charge storage, electrocatalytic generation of fuels, and ionic conductivity. MOF-derived materials with different compositions, structures, and functionalities: (left to right) porous carbon with electric double-layer capacitance, hollow structure for charge storage, and carbon-supported composite for electrocatalysis. These MOF-related functional materials enable the storage and utilization of electricity from renewable energy sources.

Fig. 2. MOF-related materials for charge storage.

(A to C) A redox-active MOF Cu(2,7-anthraquinonedicarboxylate) [Cu(2,7-AQDC)] for lithium batteries: (A) structural schematic, (B) charge-discharge profiles, and (C) cycling performance [(A) to (C), adapted with permission from Zhang et al. (25)]. (D) Schematic of electrochemical Na storage in Prussian blue crystal [(D), adapted with permission from You et al. (28)]. (E and F) Electrochemical capacitors fabricated with nanocrystals of MOFs (nMOFs): (E) structure of nMOF electrochemical capacitor and (F) comparison of energy and power densities for electrochemical capacitors made from nMOF-867 and activated carbon [(E) and (F), adapted with permission from Choi et al. (34)]. (G to I) Electronic conductive MOF for electrochemical capacitors: structural schematics of (G) conductive MOF Ni₃(2,3,6,7,10,11-hexaiminotriphenylene)₂ [Ni₃(HITP)₂] and (H) electrolyte components in Ni₃(HITP)₂; (I) cyclic voltammetry at a scan rate of 10 mV s⁻¹ at different cell voltages [(G) to (I), adapted with permission from Sheberla et al. (36)]. (J to L) MOFs as sulfur host for lithium-sulfur (Li-S) batteries: (J) schematic showing the interaction between polysulfides and MOF scaffold, (K) comparison of binding energy of lithium polysulfides to Ni-MOF or Co-MOF, and (L) charge-discharge profiles of MOF/S composite cathodes [(J) to (L), adapted with permission from Zheng et al. (38)].

Fig. 3. MOF-related materials for electrocatalysis.

(A) Schematic of a Zr-based MOF with Fe^III porphyrin linkers as a heterogeneous catalyst for ORR [(A), adapted with permission from Usov et al. (42)]. (B) Polarization curves of Ni₃(HITP)₂ under N₂ and O₂ atmosphere in 0.1 M KOH aqueous electrolyte at a scan rate of 5 mV s⁻¹ and a rotation rate of 2000 rpm [(B), adapted with permission from Miner et al. (45)]. (C to E) UMOFNs as an electrocatalyst for OER: (C) crystal structure and (D) transmission electron microscopy (TEM) image of NiCo-UMOFNs and (E) polarization curves of various OER catalysts in O₂-saturated 1 M KOH solution at a scan rate of 5 mV s⁻¹ [(C) to (E), adapted with permission from Zhao et al. (46)]. (F and G) A Co-based MOF, MAF-X27-OH, for OER: (F) structure of MAF-X27-OH and (G) polarization curves of various Co-based catalysts at pH = 14 [three MAF-X27-OH(Cu) samples refer to the MOF catalyst directly grown on the Cu substrate] [(F) and (G), adapted with permission from Lu et al. (53)]. (H and I) A Ni-S electrocatalyst deposited on the fluorine-doped tin oxide (FTO) substrate with an array of NU-1000 rods for HER: (H) schematic of the creation of NU-1000_Ni-S hybrid system and (I) polarization curves of various catalysts in 0.1 M HCl aqueous electrolyte [(H) and (I), adapted with permission from Hod et al. (54)]. GCE, glassy carbon electrodes; RHE, reversible hydrogen electrode.

Fig. 4. MOF-related materials for ionic conduction.

(A) Schematic of postsynthetic oxidation modification to synthesize UiO-66(SO₃H)₂ [(A), adapted with permission from Phang et al. (58)]. (B and C) PCMOF-5 with uncoordinated diprotic phosphonic acid groups for proton conduction: (B) 1D hydrogen-bonding array formed between phosphonic acid groups and free water molecules and (C) Arrhenius plots for PCMOF-5 at 90 and 98% RH [(B) and (C), adapted with permission from Taylor et al. (60)]. (D and E) A Fe-based MOF with imidazole for proton conduction: (D) structures of pristine Fe-MOF, imidazole physically absorbed in Fe-MOF (Im@Fe-MOF), and imidazole chemically coordinated in Fe-MOF (Im-Fe-MOF), and (E) their Arrhenius plots at 98% RH [(D) and (E), adapted with permission from Zhang et al. (65)]. (F and G) A layered anionic framework with interlayer-embedded counter cations for anhydrous proton conduction: (F) sandwich-type structure with cations (Me₂NH₂)⁺ periodically aligned in the interlayers (left) and the strongly hydrogen-bonded chains (right) and (G) Arrhenius plot under anhydrous condition [(F) and (G), adapted with permission from Wei et al. (66)]. (H and I) A Mg-based MOF with lithium isopropoxide as a lithium-ion conductor: (H) schematic of the modified channel of Mg-based MOF and (I) Arrhenius plots of MOF with liquid electrolyte (black cubes), with lithium isopropoxide and solvent (red dots), and with both lithium isopropoxide and liquid electrolyte (blue triangles) [(H) and (I), adapted with permission from Wiers et al. (71)].

Fig. 5. Compositional control of MOF-derived materials.

(A) Synthesis of porous carbon by carbonization of ZIF-8 with infiltrated furfuryl alcohol (FA) [(A), adapted with permission from Jiang et al. (74)]. (B) Synthesis of hybrid nanoporous carbon by carbonization of core-shell MOF particles [(B), adapted with permission from Tang et al. (78)]. (C) Synthesis of porous carbon-coated ZnO quantum dots by pyrolysis of IRMOF-1 [(C), adapted with permission from Yang et al. (86)]. (D and E) Various Ni-based inorganic compounds derived from NiNi-PBAs: (D) schematic of the synthesis strategy and (E) TEM images of the NiNi-PBAs (upper) and derived porous Ni-P (lower) [(D) and (E), adapted with permission from Yu et al. (96)]. (F) Synthesis of mesoporous MoC_x octahedral particles derived from NENU-5 [(F), adapted with permission from Wu et al. (102)]. (G) Synthesis of MoO₂-based composite (MoO₂@PC/RGO) from a MOF precursor containing POMs [(G), adapted with permission from Tang et al. (103)]. (H and I) A composite of Fe₃C@N-CNTs derived from a MOF-in-MOF composite: (H) schematic of the synthetic procedure and (I) microscope images of the composite precursor (left) and the derived Fe₃C@N-CNTs assemblies (right) [(H) and (I), adapted with permission from Guan et al. (84)].

Fig. 6. Morphological and structural control of MOF-derived materials.

(A) Synthesis of MOF-74-Rod, carbon nanorods, and graphene nanoribbons [(A), adapted with permission from Pachfule et al. (75)]. RT, room temperature. (B) TEM image of mesoporous Fe₂O₃ derived from MIL-88-Fe [(B), adapted with permission from Xu et al. (109)]. (C) High-resolution TEM image of mesoporous MoC_x derived from NENU-5 [(C), adapted with permission from Wu et al. (102)]. (D) High-angle annular dark-field scanning TEM image of single iron atoms (red circles) on N-doped porous carbon [(D), adapted with permission from Chen et al. (104)]. (E) Synthesis of complex hollow structures with multishells (left route) or multicompositions (right route) from Prussian blue [(E), adapted with permission from Zhang et al. (90)]. (F) Schematic of formation of NiS nanoframes from Ni-Co PBA nanocubes (upper) and microscope images of NiS nanoframes (lower) [(F), adapted with permission from Yu et al. (92)]. (G) Fabrication of hybrid Co₃O₄-carbon porous nanowire arrays using Co-based MOF arrays [(G), adapted with permission from Ma et al. (118)]. (H) Photograph of a MOF aerogel monolith and derived carbon monolith [(H), adapted with permission from Xia et al. (121)].

Fig. 7. Functionalities and applications of MOF-derived materials.

(A and B) Carbon nanorods and graphene nanoribbons derived from MOF-74-Rod for electrochemical capacitors: morphology illustrations and cyclic voltammograms (CVs) of (A) carbon nanorods and (B) graphene nanoribbons in 1 M H₂SO₄ electrolyte [(A) and (B), adapted with permission from Pachfule et al. (75)]. (C to E) Multishelled Ni-Co oxide hollow particles for charge storage: (C) TEM image and (D) CVs of Ni-Co oxide hollow particles and (E) in situ liquid-cell TEM observation of charge/discharge processes [(C) to (E), adapted with permission from Guan et al. (124)]. (F and G) Double-shelled hydroxide hollow particles (CH@LDH) as a sulfur host for Li-S batteries: (F) synthesis of sulfur-loaded double-shelled CH@LDH particles and (G) their cycling performance compared with a conventional mesoporous carbon/sulfur composite [(F) and (G), adapted with permission from Zhang et al. (91)]. (H) Polarization curves of various cobalt-based sulfide particles in 0.5 M H₂SO₄ [(H), adapted with permission from Huang et al. (129)]. (I) Polarization curve of isolated single Fe atoms on N-doped porous carbon (Fe-ISAs/CN) compared with N-doped carbon (CN) and Pt/C in O₂-saturated 0.1 M KOH (inset: scheme of Fe-ISAs/CN) [(I), adapted with permission from Chen et al. (104)]. (J and K) Hollow particles of N-doped carbon nanotubes (NCNTs) as a bifunctional catalyst: polarization curves at a rotation rate of 1600 rpm in (J) O₂-saturated 0.1 M KOH and (K) 1 M KOH [(J) and (K), adapted with permission from Xia et al. (82)].