Recent Advances in Metal‐Organic Framework Derivatives as Oxygen Catalysts for Zinc‐Air Batteries

Abstract

Electrochemical energy storage systems with high power output, large energy density, and stable performance are urgently needed. Zn-air batteries are one of the most promising candidates owing to abundant and inexpensive resources used, decent energy density, and the high reduction potential of Zn. The most significant challenge of primary and rechargeable aqueous Zn-air batteries is the relatively high overpotential due to the sluggish kinetics of oxygen reactions on the air cathode. Highly efficient oxygen catalysts derived from metal-organic framework (MOF) precursors have demonstrated remarkable capabilities for facilitating the oxygen reactions. In this contribution, we review the recent progress in state-of-the-art MOF-derived materials for use as oxygen catalysts in primary and rechargeable Zn-air batteries. We first summarize the development of several important MOF derivatives, including transition metal-nitrogen-carbon (TMÀNÀC) composites, carbon-based transition metal compounds, and metal-free carbons. The advantages and disadvantages of these MOF-derived catalysts are also discussed. Strategies for optimization of the gas-liquid diffusion and the long-range electronic transportation on the air cathode with these MOF-derived catalysts are also demonstrated. Finally, the main challenges and some perspectives for developing advanced MOF-derived catalysts applied in Zn-air batteries are provided.

Metal–organic framework based bifunctional oxygen electrocatalysts for rechargeable zinc–air batteries: current progress and prospects

“…[54][55][56] In addition, the clear structure and adjustable chemical coordination of MOFs not only bring great convenience to reveal the related catalytic mechanism, but also provide unlimited possibilities for their application in catalysis including using various metal active sites and appropriate ligands to construct conductive MOFs. 11,12,35,57 In a recent study, 2,3,6,7,10,11-hexaaminotriphenylene reacts with Ni 2+ in NH 3 aqueous solution to form Ni 3 (HITP) 2 . Dual probe and van der Waals electrical measurements prove that Ni 3 (HITP) 2 has a good conductivity.…”

“…[99][100][101] However, the conductivity of metal oxides limits their catalytic activity. 57,61,[102][103][104][105] It is worth noting that the use of metal oxides and metal nanoparticle composites, or xed metal oxides on a highly conductive carbon matrix and other reasonable strategies can effectively promote the internal and surface charge transfer and maximize the utilization of active sites, which can further improve the efficiency of ZABs. 102,106,107 The weak coordinate bond and uniform morphology of MOFs make them good precursors to prepare hollow nanostructures using the Kirkendall effect.…”

A Composite Bifunctional Oxygen Electrocatalyst for High‐Performance Rechargeable Zinc–Air Batteries

“…The anode process involves the reversible plating/stripping of zinc whereas the cathode reactions are the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR) during charge and discharge, respectively . Both ORR and OER are multi‐electron reactions occurring at multi‐phase boundaries and thus are heavily sluggish in kinetics, which renders large voltage gaps, reduced energy efficiency, and limited cycling stability . Consequently, the poor cathode kinetics regarding ORR and OER is considered as the bottleneck that limits the practical performances of rechargeable zinc–air batteries.…”

“…[12] Both ORR and OER are multi-electron reactionso ccurring at multi-phase boundaries and thus are heavily sluggish in kinetics, which renders large voltage gaps, [13] reduced energyefficiency, [14] andlimited cycling stability. [15,16] Consequently,t he poor cathode kineticsr egarding ORR and OER is considered as the bottleneckt hat limits the practical performances of rechargeable zinc-airbatteries.…”

Phosphorus/nitrogen co-doped and bimetallic MOF-derived cathode for all-solid-state rechargeable zinc–air batteries

“…[16][17][18][19][20] As sacricial precursors during a facile pyrolysis process, the MOFderived nanostructured-metals/metal-based compounds coupled with heteroatoms-doped porous carbonaceous materials can be obtained, resulting in a synergistically enhanced OER and ORR performance. 21 For example, the Co-N/C nanoparticles stringed with carbon bers were synthesized by electrospun and the pyrolysis of ZIF-67, showing a superior ORR activity due to the large surface areas. 22 Also, the MOF-derived hybrid cobalt/cobalt nitride nanoparticles integrated with nitrogen-doped carbon nanoarrays (Co/CoN x -NC) can be utilized as an active and durable air cathode for all-solid-state rechargeable zinc-air batteries, exhibiting excellent bifunctional catalytic properties toward ORR and OER.…”