Strategic Structural Design of a Gel Polymer Electrolyte toward a High Efficiency Lithium-Ion Battery

Abstract

Electrolytes have played critical roles in electrochemical energy storage. In Li-ion battery, liquid electrolytes have shown their excellent performances over decades, such as high ionic conductivity (∼10–3 S cm–1) and good contacts with electrodes. However, the use of liquid electrolytes often brought risks associated with leakage and combustion of organic electrolytes. Hence, polymer electrolytes become potential candidates to replace liquid electrolyte systems. Although solid polymer electrolytes (SPEs) offer better safety and good mechanical properties to take over liquid electrolytes, most of them only deliver low ionic conductivities (∼10–8 S cm–1) and poor contact with electrodes, resulting in poor cycle performance and low electrical capacity of the batteries. In addition, gel polymer electrolytes (GPEs) have received increasing research attention due to their relevant characteristics, which extend from liquid electrolytes and solid polymer electrolytes. In this review, state-of-the-art samples of gel polymer electrolytes are elucidated with respect to their structural design and electrochemical properties to determine their application potential in Li-ion batteries (LIBs). First, we present the general requirements of GPEs for LIBs applications, followed by important electrochemical properties of GPEs for LIBs including ionic conductivity, transference number, and ionic transport mechanisms. Furthermore, recent progress of common polymers, namely, polyether, polyvinyl, polynitrile, polycarbonate, and polyacrylate, as polymer host of GPEs has been carefully explained. Finally, the alternative polymers were also discussed to provide new approaches for further developments of GPEs to fulfill the demanded properties for practical applications.

Tough and Flexible, Super Ion‐Conductive Electrolyte Membranes for Lithium‐Based Secondary Battery Applications

“…Polyether, polynitrile, polycarbonate, polyarylate, and their derivatives have been used as polymer matrices which can dissolve Li salts by coordination between Li ions and polar groups or electrostatic forces in polymeric chains. [ 23–25 ] Still, their σ values are lower than the required conductivity of 10 −3 S cm −1 , and lower than the σ values of conventional electrolytes. Therefore, other alternative SPE systems with better physicochemical and electrochemical properties, such as polymer‐in‐salts containing plasticizer or organic solvents, single‐ion conducting polymer electrolytes that require modification of the polymer matrix or use of new types of Li salt, and organic–inorganic composite polymer separators (CPSs), have been developed in the past two decades.…”

Semi‐Interpenetrating Polymer Electrolyte as a Coating Layer Constructed on Polyphenylene Sulfide Nonwoven to Afford Superior Stability and Performance for Lithium‐Ion Batteries

“…High power lithium ion battery (LIB), as an energy storage equipment, has raised scientists much attention with the development of electric vehicle and renewable energy. [1,2] Separator sandwiched between two electrodes plays an important role in blocking the passage of electrons while allowing the delivery of Li + . Hence, higher requirements are put forward that separator must be able to tolerate high temperature, adsorb more electrolyte and benefit to transfer Li + , which can finally meet the demand of safety and charge/discharge performance followed by the increase of LIB power density.…”

“…High power lithium ion battery (LIB), as an energy storage equipment, has raised scientists much attention with the development of electric vehicle and renewable energy [1,2] . Separator sandwiched between two electrodes plays an important role in blocking the passage of electrons while allowing the delivery of Li + .…”

A Review of the Use of GPEs in Zinc-Based Batteries. A Step Closer to Wearable Electronic Gadgets and Smart Textiles

“…Since ionic conductivity is directly proportional to the concentration of charged species and their electrical mobility, as per σ = n i *q i *µ i , it is expected that ionic conductivity to be lower in GPEs as the mobility of ions is higher in liquid electrolytes [114]. • High Cationic Transference Number (t + ): Besides the ionic conductivity, the transference number of polymer electrolytes is an important figure of merit when assessing their efficacy.…”

“…The cationic transference number is the cation mobility relative to the anion in single salts GPEs. In GPEs, working species need to have a transference number close to unity [114].…”