Probing the synergistic effect of metal-organic framework derived Co-Nx rich interwoven hierarchical porous carbon tube encapsulated dual redox active nanoalloy for high-performance Zn-air battery and supercapacitor applications.

Abstract

Rechargeable zinc-air batteries (ZABs) with high-performance and stability is desirable for encouraging the transition of the technology from academia to industries. However, achieving this balance remains a formidable challenge, primarily due to the requirement of robust, earth-abundant reversible oxygen electrocatalyst. The present study introduces a simple strategy to synthesize Co-N_x rich nanoalloy with N-doped porous carbon tubes (NiCo@NPCTs). The optimized catalyst is bestowed with high electrochemical surface area, and three dimensional (3D) interwoven N-doped PCTs. Moreover, the presence of dual redox-active sites synergistically promotes rapid mass/charge transfer for oxygen electrocatalysis. These features offer excellent reversibility for oxygen electrocatalysis with a reversible oxygen potential gap (ΔE) of 0.74 V. The NiCo@NPCTs is utilized as an air-electrode for designing ZABs and using the same electrode-material asymmetric supercapacitor device (ASC) is fabricated. The assembled ZAB delivers an impressive peak power density of 298 mW cm^-2 and specific capacity of 731mAh g^-1 at 50 mA cm^-2, along with high rate-capability, durable round-trip voltaic-efficiency. The as-fabricated ASC also shows exciting performance with negligible fading in capacitance and columbic efficiency after 10,000 continuous charge-discharge cycles at a 10 A/g current density. In addition, ZAB-ASC integrated device is assembled, showing real-time application. Thus, the synthesized electrode-material holds great promise for electrocatalysis and also for diverse energy storage applications.