Negatively Charged Hydrophobic Carbon Nano‐Onion Interfacial Layer Enabling High‐Rate and Ultralong‐Life Zn‐Based Energy Storage

Abstract Zn‐based electrochemical energy storage (EES) systems are attracting more attention, whereas their large‐scale application is restricted by the dendrite and parasitic reaction‐caused unstable Zn anodes. Herein, a negatively charged hydrophobic carbon nano‐onion (CNO) interfacial layer is proposed to realize ultrastable and high‐rate Zn anodes, enabling high‐performance Zn‐based EES. For the CNO interfacial layer, its hydrophobicity not only blocks active water but also reduces the Zn 2+ desolvation barrier, and meanwhile, the negatively‐charged CNO nanoparticles adsorb Zn 2+ and repel SO 4 2− to homogenize Zn 2+ flux, accelerate Zn 2+ desolvation and suppress the self‐corrosion of Zn anodes. Besides, the conductive CNO interfacial layer increases the surface area for the Zn deposition to reduce local current density. Consequently, under the modulation of the CNO interfacial layer, Zn plating/stripping exhibits impressive reversibility with an average Coulombic efficiency of 99.4% over 800 cycles, and Zn anodes present significantly enhanced electrochemical stability and rate performance, whose operation lifetime exceeds 2000 h at 1 mA cm −2 and 350 h even at 10 mA cm −2 . Moreover, high‐rate and ultralong‐life Zn‐ion hybrid supercapacitors are achieved with the CNO interfacial layer‐modulated Zn anode and activated CNO cathode. This work provides new thinking in regulating the Zn deposition interface to realize high‐performance Zn‐based EES.