Revealing the effects of conductive carbon materials on the cycling stability of rechargeable Zn‐air batteries

Abstract

Summary Rechargeable zinc‐air batteries (RZABs) are considered to be one of the promising electrochemical energy sources, and considerable efforts are devoted to high‐performance bifunctional catalysts. Since the conductivity of catalysts is usually unsatisfactory, conductive carbon materials are needed in electrodes to provide the electron pathway. However, the effects of conductive carbon materials on the cycling stability of RZABs are usually overlooked. Herein, this topic is comprehensively investigated combing the electrochemical testes, in‐situ oxygen monitor during charging, and characterization of the electrodes and electrolytes. Three kinds of electrodes made of bi‐functional catalysts without additional carbon (N/A) and with Vulcan carbon (VC) and carbon nanotubes (CNT) are taken as examples. The results show that the CNT‐based electrode releases the most oxygen under the same charging current density, which is 1.43 times that of the VC‐based electrode and exhibits high stability in terms of voltage profile, structure morphology, and surface state. In addition, carbon corrosion is a serious issue for RZABs, which not only decreases the oxygen releasing efficiency but also contaminates the electrolyte. This work demonstrates the significant roles of conductive carbon materials in cycling stability and indicates that the in‐situ gas analysis is essential to more rigorously evaluate the charging performance of RZABs.

Recent advances of bifunctional catalysts for zinc air batteries with stability considerations: from selecting materials to reconstruction

“…Carbonaceous materials play an important role in zinc-air batteries; however, the effects of conductive carbon materials on the cycling stability of ZABs are usually overlooked. 120 As shown in Table 1, metal-free carbon materials exhibit similar stability in the alkaline electrolyte at least at 10 mA cm −2 for the ORR reaction, which is close to that of benchmark materials like Pt/C for ORR and Ir/C for the OER process. Most doped carbon materials are known to have long-term stability in the ORR reaction, but there is insufficient data for the OER process.…”

“…Active sites like those of metal-N-C can be embedded into a kind of layered structure and oxides can be attached to CNTs for increased conductivity. 120 (2) Choosing a high activity ORR catalyst. ORR reactions determine the discharge power density in a low ambient electrolyte.…”

Nonnoble metal oxides for high‐performance Zn‐air batteries: Design strategies and future challenges

“…Accordingly, the cation doping strategy is firstly used to improve its catalytic activity. As demonstrated in the literature, cations in A‐site are the main cause for the thermal resistance of perovskite, while cations in B‐site are relative to the ORR/OER activity 87,88 . So far, the A‐site and/or B‐site doping is commonly considered to build up perovskite oxides with high oxygen catalytic performance.…”

“…As demonstrated in the literature, cations in A-site are the main cause for the thermal resistance of perovskite, while cations in B-site are relative to the ORR/OER activity. 87,88 So far, the A-site and/or B-site doping is commonly…”

“…In general, the catalytic activity of perovskite oxides towards ORR/OER mainly relies on the B-site transition metal. 87,88 According to the Sabatier principle, the best candidate for oxygen reduction and evolution needs to have a suitable surface oxygen interaction force. 92,93 In other words, the binding capacity of the catalyst surface and related oxygen species cannot be too weak or too strong.…”