Reversing Zincophobic/Hydrophilic Nature of Metal-N-C via Metal-Coordination Interaction for Dendrite-Free Zn Anode with High Depth-of-Discharge.

ABSTRACT

Dendrite-free Zn metal anodes with high depth-of-discharge (DoD) and robust cycle performances are highly desired for the practical application of aqueous Zn-ion batteries. Herein, the zincophobic/hydrophilic nature of Metal-N-C through manipulating the electronic interactions between metal and coordination atoms is successfully reversed, thereby fabricating a zincophilic/hydrophobic asymmetric Zn-N3Py+1Pr-C (consisting of a Zn center coordinated with 3 pyridinic N atoms and 1 pyrrolic N atom) host, which realizes uniformed Zn deposition and a long lifespan with high DoD. The experimental and theoretical investigations demonstrate weakened interaction between pyrrolic N and metal center in the asymmetric Zn-N3Py+1Pr-C triggers downshift of the Zn 3d-band-center and a new localization nonbonding state in the N and C 2p-band, resulting in preferred Zn adsorption to water adsorption. Consequently, the asymmetric Zn-N3Py+1Pr-C host delivers small Zn nucleation overpotential and high Coulombic efficiency of 98.3% over 500 cycles. The symmetric cells with Zn-N3Py+1Pr-C@Zn anode demonstrate 500 h dendrite-free cycles at DoD up to 50%. The Zn-N3Py+1Pr-C@Zn/S-PANI full cell also shows a robust long-term cycle performance of 1000 cycles at 10 A g-1. This strategy of constructing zincophilic/hydrophobic Metal-N-C may open up their application for the dendrite-free metal anode.