WC/Co7Fe3 heterojunction embedded in N,P co-doped hierarchical carbon enables rechargeable/flexible Zn-air battery
Huimin Mao, Xiaobin Liu, Siqi Wu, Yixin Fu, Guishan Liu, Guizhong Zhou, Lei Wang
Abstract
Rational design and synthesis of bifunctional oxygen electrocatalysts with high activity and stability are key challenges in the development of rechargeable Zn-air batteries (ZABs). In this paper, tungsten carbide (WC) and Co7Fe3 embedded in N,P co-doped hierarchical carbon (WC/Co7Fe3-NPHC) was prepared by using zeolite imidazolate frameworks as precursor. Density functional theory demonstrates that the mutual adjustment among the WC, Co7Fe3, and N,P co-doped carbon at the three-phase heterojunction interface makes the catalyst possess moderate adsorption strength, and greatly improves the conductivity and electron transfer rate of the catalyst. As a result, the WC/Co7Fe3-NPHC exhibits a low overall oxygen redox potential difference of 0.72 V, while the ZAB assembled by WC/Co7Fe3-NPHC as an air cathode exhibits ultra-long cycle stability of over 550 h. Futhermore, WC/Co7Fe3-NPHC can keep good charge and discharge stability at different bending angles when applied to flexible solid ZAB.