Asymmetric Air Cathode Design for Enhanced Interfacial Electrocatalytic Reactions in High‐Performance Zinc–Air Batteries

Abstract

The rechargeable zinc–air battery (ZAB) is a promising energy storage technology owing to its high energy density and safe aqueous electrolyte, but there is a significant performance bottleneck. Generally, cathode reactions only occur at multiphase interfaces, where the electrocatalytic active sites can participate in redox reactions effectively. In the conventional air cathode, the 2D multiphase interface on the surface of the gas diffusion layer (GDL) inevitably results in an insufficient amount of active sites and poor interfacial contact, leading to sluggish reaction kinetics. To address this problem, a 3D multiphase interface strategy is proposed to extend the reactive interface into the interior of the GDL. Based on this concept, an asymmetric air cathode is designed to increase the accessible active sites, accelerate mass transfer, and generate a dynamically stabilized reactive interface. With a NiFe layered‐double‐hydroxide electrocatalyst, ZABs based on the asymmetric cathode deliver a small charge/discharge voltage gap (0.81 V at 5.0 mA cm−2), a high power density, and a stable cyclability (over 2000 cycles). This 3D reactive interface strategy provides a feasible method for enhancing the air cathode kinetics and further enlightens electrode designs for energy devices involving multiphase electrochemical reactions.

d-Orbital steered active sites through ligand editing on heterometal imidazole frameworks for rechargeable zinc-air battery

“…6g . Specifically, the valence electron configuration of Zn II is 3 d 10 with fully occupied d -orbitals in the π-symmetry t 2 ( d xy, xz, yz ) orbitals 57 . For this reason, electron repulsion is the dominating interaction between the bridging N and Zn.…”

“…These superiorities mainly originate from oxygen-based electrochemistry in aqueous systems, but their full potential has yet to be realized because of high polarization and short lifespan at the air cathodes [6][7][8] . As such, the core of ZABs development lies in exploring air cathodes that are capable of efficiently catalyzing both oxygen reduction (ORR) and evolution reactions (OER) for long working periods [9][10][11][12] . Platinum on carbon (Pt/C) and ruthenium oxide (RuO 2 ) are the respective ORR and OER benchmarks, however, their applications in rechargeable ZABs are not favored due to their scarcity and inferior bifunctionality 7,13 .…”

“…However, application of ZIFs as air electrode in ZABs remains unexplored, which is ascribed to the impediments in controls over mass/charge transfer and intrinsic activity of the materials. Specifically, pristine ZIFs are mostly microporous, which usually leads to severe electrolyte flooding due to capillarity action, and thereby impedes O 2 accessibility towards active sites 10,27,32 . Besides, their low electrical conductivity inevitably causes sluggish charge transfer 33 .…”

Advanced energy materials for flexible batteries in energy storage: A review

“…124 Current collectors can be also made from carbonaceous and polymeric materials with various dimensions. 125 Typical building blocks includes CNTs, [126][127][128] carbon fibers, [129][130][131][132][133] carbon cloth (CC), 134,135 graphene, [136][137][138][139] polyacrylonitrile (PAN), 140,141 cellulose, [142][143][144] and their hybrids. 145 These current collectors are featured with high flexibility, extraordinary conductivity, light weight and large surface area, favoring mass/charge transport, active material supports, and volume change accommodation.…”

Direct growth of ordered N‐doped carbon nanotube arrays on carbon fiber cloth as a free‐standing and binder‐free air electrode for flexible quasi‐solid‐state rechargeable Zn‐Air batteries

“…13,14 However, the random stacking or the poor dispersion of the catalyst inevitably results in poor transport of oxygen and electron through the air electrode, which may cause sluggish reaction kinetics. 15 Refer to this point, Zhang's group proposed a liquid-phase chemical method to prepare a NiFe-layer double hydroxide-loaded asymmetric air cathode with internal three-dimensional (3D) multiphase interface, thus allowing oxygen diffusion and electrolyte permeation within the 3D-air electrode, 13 and the ZAB with this 3Dair electrode demonstrated promising cell performance. By rationally designing 3D-air electrode with an ordered structure, the gas permeation within the void space of air electrode and electronic conductivity inside the electrode bulk is greatly facilitated, improved electrode reaction kinetics is then expected.…”