Regulating Uniform Zn Deposition via Hybrid Artificial Layer for Stable Aqueous Zn-Ion Batteries

Abstract

Aqueous Zn-ion batteries (ZIBs) have great potential as promising candidates for next-generation energy conversion and storage devices, benefiting from competitive theoretical capacity, low cost, and high security. However, further applications of ZIBs are impeded by dendrite generation and side reactions. Herein, considering that Zn dendrites are caused by nonuniform metal deposition, involving uneven electric field and Zn2+ ion flux, a dual-functional carbon-coated NaTi2(PO4)3 (NTP-C) artificial protective layer with large surface area is constructed onto the surface of metallic Zn to stabilize Zn anode and regulate uniform Zn deposition. Benefiting from a synergistic strategy, NTP-C coating not only takes advantages of carbon to provide abundant Zn deposition sites to homogenize nucleation, adjust electric field distribution, and reduce local current density but also utilizes the ionic channel in NTP structure to modulate the distribution of Zn2+ flux at the same time. Consequently, the NTP-C@Zn symmetrical cell exhibits a stable cycling for more than 600 h with a low polarization (18.6 mV) at 1 mA cm−2/1 mAh cm−2. Especially, the NTP-C@Zn symmetrical cell even enables a steady plating/stripping process at a harsh condition (100 mA cm−2) without short circuit, indicating a potential application of high-load electrodes or supercapacitors. Furthermore, the NTP-C@Zn//α-MnO2 full cell also displays enhanced electrochemical performance for 1200 cycles with a capacity retention of 76.6% under 5 C (~1.5 A g−1). This work provides a synergistic strategy combining two protective mechanisms and delivers new inspirations for the improvement of stable Zn anode in aqueous ZIBs.