An in-situ grown high-efficiency Zn-terephthalate metal-organic framework/ZnO hybrid interface protection layer to achieve highly reversible dendrite-free Zn anodes

Lately, aqueous zinc-ion batteries (AZIBs) have stood out from numerous power storage equipment owing to their considerable theoretical capacity, convenient operation and trustworthy safety; unfortunately, inevitable dendrite growth and severe side reactions on the surface of Zn metals degrade the reversibility of Zn anodes. Herein, a high-efficiency Zn-terephthalate metal-organic framework (Zn-TPA-MOF)/ZnO hybrid interface protection layer (Zn-TPA-MOF/ZnO) grown in-situ on the pre-oxidized Zn foil surface is proposed to suppress the side reactions and dendrite growth for improving the reversibility of Zn anodes. The Zn-TPA-MOF/ZnO hybrid interface protection layer with strong hydrophobicity/zincophilicity facilities the rapid desolvation of Zn (H2O)(6)(2+), improves Zn2+ deposition kinetics, homogenizes the surface electric field and simultaneously constrains the 2D diffusion of Zn2+. Moreover, the Zn anode with the hybrid protection film exhibits high ionic conductivity (3.86 mS cm(-1)), low electrical conductivity (0.00607 mS cm 1), large transfer number of Zn2+ of 0.70 and low activation energy (55.87 kJ mol(-1)), efficiently accelerating the interface transfer of zinc ions during electrochemical reactions. Therefore, the Zn-TPA-MOF/ZnO@Zn parallel to Zn-TPA-MOF/ZnO@Zn cell possesses an extremely long cycling life of over 3020 h at 1 mA cm 2/1 mAh cm(-2), 40 times longer than the cell of Zn parallel to Zn (76 h); moreover, the Zn-TPA-MOF/ZnO@Zn//Cu asymmetric cell demonstrates a superior cycling life of over 4200 cycles at 0.5 mA cm 2/0.25 mAh cm(-2), and the average Coulombic efficiency of the cell is as high as 99.65%. Besides, the Zn-TPA-MOF/ZnO@Zn//VS4 full cell displays a reversible capacity of 106.6 mAh/g with the high capacity-retention of 121.39 % at 5 A/g after 1000 cycles. This investigation proposes a feasible strategy to in situ grow hydrophobic/zincophilic hybrid interface protection layer to achieve highly reversible Zn anodes.

Automated summary

By in-situ growing a Zn-TPA-MOF/ZnO hybrid interface protection layer on pre-oxidized Zn foil surface, the side reactions and dendrite growth of Zn anodes can be suppressed, leading to improved reversibility. The hybrid protection film exhibits high ionic conductivity and low electrical conductivity, which can efficiently accelerate the interface transfer of zinc ions. The results demonstrate that the Zn anode with the hybrid protection film has a significantly longer cycling life and higher Coulombic efficiency compared to traditional Zn anodes.