Abstract:
The hydrogel-based solid-state Zn-ion batteries have attracted increasing attention in the wearable electronics as flexible energy storage due to their good mechanical stability, eco-friendliness and safety. However, their performance is limited in low temperature owing to weak interfacial adhesion and easily freezing. Therefore, how to design and develop hydrogel-based solid Zn-ion batteries with excellent interface stability and low temperature adaptability is an urgent problem to be solved. In this paper, an anti-freezing hydrogel electrolyte with high self-adhesion was prepared by introducing nanohydroxyapatite (HAp), Ag@Lignin nanoparticles (Ag@Lignin NPs), and zinc chloride (ZnCl
2) into the polyacrylamide (PAAm) network. Zn|hydrogel electrolyte|PANI Zn-ion battery with robust interfacial toughness was prepared in a layer-by-layer assembly with Zn metal electrode, hydrogel electrolyte and polyaniline (PANI). This work has investigated the effect of interfacial adhesion and low-temperature electrochemical performance. The results show that the abundant catechol groups of Ag@Lignin NPs in the hydrogel electrolyte endow the hydrogel with robust adhesion, reaching a high interfacial toughness of 467.4 J·m
−2 and shear strength of 95.7 kPa at –60℃ for the hydrogel electrolyte/Zn. Then, the interfacial compatibility between the hydrogel electrolyte and Zn electrode was studied, which indicates that the introduction of Ag@Lignin NPs reduces the overpotential of the Zn|hydrogel electrolyte|Zn symmetric cell, thus enabling stable Zn plating/stripping cycles even at –60℃. The assembled Zn||PANI solid-state battery exhibits excellent low-temperature performance, delivering high capacity of 22.1 mA·h·g
−1 at –60℃. Meanwhile, the Zn||PANI solid-state battery demonstrates satisfactory cycling stability, with an average coulombic efficiency of 95.83% and a capacity retention of 65.20% after 300 charging/discharging cycles at –40℃. More encouragingly, the assembled Zn-ion battery presents impressive deformation stability, which is able to tolerate dynamic tension deformations and sustain high capacity retention of 88.3% after 40 tension cycles at 20% strain, showing excellent flexible performance.