Copper Collector Generated Cu⁺/Cu²⁺ Redox Pair for Enhanced Efficiency and Lifetime of Zn–Ni/Air Hybrid Battery

Abstract

Although Zn–Ni/air hybrid batteries exhibit improved energy efficiency, power density, and stability compared with Zn–air batteries, they still cannot satisfy the high requirements of commercialization. Herein, the Cu+/Cu2+ redox pair generated from a copper collector has been introduced to construct the hybrid battery system by combining Zn–air and Zn–Cu/Zn–Ni, in which CuXO@NiFe-LDH and Co–N–C dodecahedrons are respectively adopted as oxygen evolution (OER) and oxygen reduction (ORR) electrodes. For fabricating CuXO@NiFe-LDH, the Cu foam collector is oxidized to in situ form 1D CuXO nanoneedle arrays, which could generate the Cu+/Cu2+ redox pair to enhance battery efficiency by providing an extra charging–discharging voltage plateau to reduce the charging voltage and increase the discharge voltage. Then, the 2D NiFe hydrotalcite nanosheets grow on the nanoneedle arrays to obtain 3D interdigital structures, facilitating the intimate contact of the ORR/OER electrode and electrolyte by providing a multichannel structure. Thus, the battery system could endow a high energy efficiency (79.6% at 10 mA cm–2), an outstanding energy density (940 Wh kg–1), and an ultralong lifetime (500 h). Significantly, it could stably operate under harsh environments, such as oxygen-free and any humidity. In situ X-ray diffraction (XRD) combined with ex situ X-ray photoelectron spectroscopy (XPS) analyses demonstrate the reversible process of Cu–O–Cu ↔ Cu–O and Ni–O ↔ Ni–O–O–H during the charging/discharging, which are responsible for the enhanced efficiency and lifetime of battery.

Cobalt Nanoparticles Encapsulated with N-Doped Bamboo-Like Carbon Nanofibers as Bifunctional Catalysts for Oxygen Reduction/Evolution Reactions in a Wide pH Range

“…The excellent performance of Co–N/C fiber highlights the advantage of the directly grown N-doped carbon nanofiber-encapsulated Co nanoparticles on ZIF-67-derived carbon flakes. Outwardly extending bamboo-like carbon nanofiber-encapsulated Co nanoparticles facilitate fast reactant transfer by promoting an improved contact between the electrolyte and active sites . Moreover, since the desorption of O 2 product has a significant impact on the OER process, the large surface area of the carbon nanofiber may serve as the channels to enhance the desorption of the O 2 product into the electrolyte .…”

“…Outwardly extending bamboo-like carbon nanofiber-encapsulated Co nanoparticles facilitate fast reactant transfer by promoting an improved contact between the electrolyte and active sites. 71 Moreover, since the desorption of O 2 product has a significant impact on the OER process, the large surface area of the carbon nanofiber may serve as the channels to enhance the desorption of the O 2 product into the electrolyte. 72 These 1D structures also serve as conductive pathways that rapidly transfer electrons during the OER process.…”

Research progress on the construction of synergistic electrocatalytic ORR/OER self-supporting cathodes for zinc–air batteries

“…The highest charge discharge efficiency of this hybrid battery could reach 79.6%, breaking through the 65% efficiency of traditional ZABs. 169 Ma et al synthesized a cobalt oxide rich in oxygen vacancies by plasma etching and constructed a new type of zinc-cobalt oxide and zinc-air hybrid battery. (Zinc-Co 3 O 4−x ) Co 3 O 4 was the cathode material of zinc-ion battery.…”

“…8b). 169 Li et al synthesized a porous carbon nanofiber-supported CoS 2 /Cu 2 S heterostructure composite (CoS 2 /Cu 2 S-NF) as a high-efficient air-cathode for ZABs. The stability of the catalyst were investigated by operando XRD.…”

“…The highest charge discharge efficiency of this hybrid battery could reach 79.6%, breaking through the 65% efficiency of traditional ZABs. 169…”