Gel Polymer Electrolytes for Electrochemical Energy Storage

Abstract

storage devices with adjustable shapes and high flexibility, which is promising for the burgeoning portable and wearable electronics. [7][8][9] Furthermore, the flexibility and elasticity of GPEs are also prone to tolerate the volume change of electrode materials and the dendrites of lithium metal during charge and discharge processes. [10][11][12][13] As a consequence, GPEs have become one of the most desirable alternatives among various electrolytes for the electrochemical energy storage devices, and significant progress has been made in lithium-ion batteries (LIBs), supercapacitors (SCs), lithium-oxygen (Li-O 2 ) batteries as well as the other kinds of electrochemical energy storage devices, such as sodium-ion batteries, lithium-sulfur batteries, fuel cells, and zinc-air batteries. [14][15][16] In order to meet the requirements of wearable devices for flexibility and deformability, more special GPEs with tough, [17] stretchable, [18] and compressible [19] functionalities have been also developed.Typically, a polymeric framework is adopted in GPEs as host material, providing high mechanical integrity. Several criteria for a good polymer host lie in: [20][21][22] (i) fast segmental motion of polymer chain; (ii) special groups promoting the dissolution of salts; (iii) low glass transition temperature (T g ); (iv) high molecular weight; (v) wide electrochemical window; (vi) high degradation temperature. Within the framework, the salts in the GPEs serve as the sources of the charge carriers, which are generally required to have large anions and low dissociation energy for easier dissociating-induced free/mobile ions. According to the types of electrolytes, there are four categories of GPEs based on proton, [23] alkaline, [24] conducting salts, and ionic liquids (ILs). [25] The criteria for an appropriate electrolyte include: [26][27][28] (i) good dissociation without forming ion pairs or ion aggregation; (ii) high thermal, chemical, and electrochemical stability; (iii) high ionic conductivity. In order to dissolve both the polymer hosts and electrolytic salts, the organic/ aqueous solvents are introduced to provide the medium for ionic conduction. A good solvent should simultaneously have high dielectric constant (ɛ > 15), donor number for more dissociation of ion and chemical and electrochemical stability. Organic solvents normally include ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dimethyl formamide (DMF), dimethyl sulphoxide, ethyl methyl carbonate, and tetrahydrofuran.To prepare a high-performance GPE, it is essential to select the species of host polymer, solvent, and electrolytic salt, and then blend them by solution or melt processes, such as casting With the booming development of flexible and wearable electronics, their safety issues and operation stabilities have attracted worldwide attentions. Compared with traditional liquid electrolytes, gel polymer electrolytes (GPEs) are preferred due to their higher safety and adaptability to the design of ...

Uniform Virus‐Like Co–N–Cs Electrocatalyst Derived from Prussian Blue Analog for Stretchable Fiber‐Shaped Zn–Air Batteries

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Super‐Stretchable Zinc–Air Batteries Based on an Alkaline‐Tolerant Dual‐Network Hydrogel Electrolyte

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A Single‐Ion Conducting Borate Network Polymer as a Viable Quasi‐Solid Electrolyte for Lithium Metal Batteries

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