Self-Healing and Anti-CO₂ Hydrogels for Flexible Solid-State Zinc-Air Batteries

Abstract

Flexible solid-state zinc-air batteries (ZABs) generally suffer from poor electrolyte/electrode contact and mechanical degradation in practical applications. In addition, CO 2 corrosion is also a common issue for ZABs with alkaline electrolyte. Herein, we report a thermoreversible alkaline hydrogel electrolyte that can simultaneously solve the aforementioned problems. Through a simple cooling process, the hydrogel electrolyte transforms from solid state to liquid state that can not only restore the deformed electrolyte layer to its original state but also rebuild intimate contact between electrode and electrolyte. Moreover, the ZAB based on this hydrogel electrolyte exhibits an unprecedented anti-CO 2 property. As a result, such a battery shows almost 2.5 times discharge duration than that of ZAB based on liquid electrolyte.

Multi‐Functional Hydrogels for Flexible Zinc‐Based Batteries Working under Extreme Conditions

“…Unfortunately, this is a common problem in other thermo‐reversible hydrogels (e.g., Pluronic) as well, and no effective solution has ever been reported. [ 29,37 ] In the future, more hydrated zinc salt and hydrogel structure modification methods can be exploited to improve the compatibility with zinc ions.…”

“…Most recently, Bae and colleagues reported an application of alkaline Pluronic solid‐state electrolyte (APSE) in ZABs. [ 37 ] Besides the self‐healing ability, the APSE also exhibited an unprecedented CO 2 ‐tolerance property, which greatly elongated the battery lifetime in the ambient environment compared to the liquid KOH (Figure 16h). Furthermore, two series bent batteries could light up an LED, demonstrating its potential in wearable devices.…”

“…[ 32–34 ] For example, additives like SiO 2 and graphene oxide (GO) have been employed to promote ionic conductivity of hydrogel electrolytes, [ 35,36 ] and new strategies like sol‐gel transition have been applied to obtain an intimate electrode/electrolyte interface. [ 37 ] Recent progress about the hydrogel materials for flexible zinc‐based batteries has also been comprehensively summarized. [ 38–41 ] These reports mainly discussed strategies for improving battery performance under room temperature and undisturbed situations.…”

Integrated Bifunctional Oxygen Electrodes for Flexible Zinc–Air Batteries: From Electrode Designing to Wearable Energy Storage

“…Nevertheless, the ionic conductivity (10 −4 -10 −3 S cm −1 ) and water uptake capability of PVA are still insufficient to ensure the high energy/ power density and the long-lasting durability of FZABs. To this issue, it is rational to incorporate poly (acrylic acid) (PAA), [146] poly(ethylene glycol) (PEG), [147] poly(ethylene oxide) (PEO), [148] polyacrylate, [149,150] polyacrylamide (PAM) [151] or other inorganic additives (e.g., GO, SiO 2 ) into the polymeric gel electrolytes to improve the OH − conductivity (0.02-0.2 S cm −1 ), water take-up ability, and mechanical strength. In 2018, Zhi and coworkers developed a sodium polyacrylate hydrogel electrolyte (PANa) with enhanced ionic conductivity (0.17 S cm −1 ) and high water-retention ability, contributing to superb cycling stability (800 cycles/160 h), and especially the acrylate-ion-facilitated fulfillment of strong electrode/electrolyte interaction for FZABs.…”

Enzyme immobilization in hydrogels: A perfect liaison for efficient and sustainable biocatalysis

“… Overview of properties, materials, and applications of hydrogels. References: [i] = [ 123 , 124 , 125 ]; [ii] = [ 126 , 127 , 128 , 129 ]; [iii] = [ 130 ]; [iv] = [ 131 , 132 ]; [v] = [ 133 , 134 ]; [vi] = [ 135 , 136 ]; [vii] = [ 137 , 138 , 139 ]; [viii] = [ 140 , 141 ]; [ix] = [ 142 , 143 ]; [x] = [ 144 ]; [xi] = [ 145 ]; [xii] = [ 70 , 146 , 147 ]; [xiii] = [ 148 ]; [xiv] = [ 149 , 150 , 151 ]; [xv] = [ 152 , 153 ]; [xvi] = [ 154 , 155 ]; [xvii] = [ 156 , 157 , 158 , 159 ]; [xviii] = covered within this review …”