Aqueous zinc (Zn)-ion batteries are considered very promising in grid-scale energy storage systems. However, the dendrite, corrosion, and H2 evolution issues of Zn anode have restricted their further applications. Herein, to solve these issues, a hydrophilic layer, consisting of a covalent organic polymer (COP) and carboxylmethyl cellulose (CMC), is designed to in situ construct a multifunctional quasi-gel (COP-CMC/QG) interface between Zn metal and the electrolyte. The COP-CMC/QG interface can significantly improve the rechargeability of the Zn anode through enhancing Zn2+ transport kinetics, guiding uniform nucleation, and suppressing Zn corrosion and H2 evolution. As a result, the COP-CMC-Zn anode exhibits a reduced overpotential (12 mV at 0.25 mA cm–2), prolonged cycle life (over 4000 h at 0.25 mA cm–2 and 2000 h at 5 mA cm–2 in symmetrical cells), and elevated full-cell (Zn/MnO2) performance. This work provides an efficient approach to achieve long-life Zn metal anodes and paves the way toward high-performance Zn-based and other metal-ion batteries.

The room-temperature liquid anode is a feasible method for building dendrite-free alkali-metal-based batteries. The Na−K phase diagram shows a eutectic point as low as 260.53 K with a long liquid range below 298 K with the molar fraction of potassium ranging from 30.48 to 84.99%. However, the NaK alloy exhibits a very high surface tension preventing it from wetting the current collector surface. Herein, a novel homogeneous dual solid−liquid composite in which the liquid alloy is fixed by the solid Na 15 Sn 4 phase and perfectly stuffed into the grid of the mesh has been designed and fabricated. Based on the liquid range of the NaK alloy, the Na−K−Sn mixture possesses a theoretical specific capacity of 768 mAh g −1 . The symmetric cells of the Na−K−Sn@mesh electrodes cycled at 2.0 mA cm −2 with 1.0 mAh cm −2 showed little fluctuations with the stable overpotential of ∼200 mV for 550 h, and the full cell coupled with Na 3 V 2 (PO 4 ) 3 showed an initial discharge capacity of 103 mAh g −1 at 2 C with a retention of 90% after 800 cycles. When the high-loading Na 3 V 2 (PO 4 ) 3 electrode is applied in the full cell, a stable cycling life is still maintained with a good capacity retention of 86% over 190 cycles (2.7 mAh cm −2 ) and 91% over 60 cycles (5.2 mAh cm −2 ).

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