Ionic‐Liquid‐Based Polymer Electrolytes for Battery Applications

Abstract

The advent of solid-state polymer electrolytes for application in lithium batteries took place more than four decades ago when the ability of polyethylene oxide (PEO) to dissolve suitable lithium salts was demonstrated. Since then, many modifications of this basic system have been proposed and tested, involving the addition of conventional, carbonate-based electrolytes, low molecular weight polymers, ceramic fillers, and others. This Review focuses on ternary polymer electrolytes, that is, ion-conducting systems consisting of a polymer incorporating two salts, one bearing the lithium cation and the other introducing additional anions capable of plasticizing the polymer chains. Assessing the state of the research field of solid-state, ternary polymer electrolytes, while giving background on the whole field of polymer electrolytes, this Review is expected to stimulate new thoughts and ideas on the challenges and opportunities of lithium-metal batteries.

Gel Polymer Electrolytes for Electrochemical Energy Storage

“…However, the reported solid polymer electrolytes mostly deliver low ionic conductivities (10 −8 −10 −5 S cm −1 ) and poor interfaces with electrodes, resulting in deteriorated cycle performance. [1][2][3][4] The inferior mechanical property has also limited their developments. To this end, combined the advantages of both the liquid and solid electrolytes, gel polymer electrolytes (GPEs) have attracted increasing attentions as they can function as not only electrolytes but also separators.…”

“…To this end, combined the advantages of both the liquid and solid electrolytes, gel polymer electrolytes (GPEs) have attracted increasing attentions as they can function as not only electrolytes but also separators. [1,5,6] Besides, due to the workability of polymers, the GPEs can render the energy www.advenergymat.de method, [29,30] in situ polymerization, [31,32] extraction-activation method, [33] and phase inversion method. [34][35][36][37][38][39][40] For practical applications, these requirements should be met at the same time: (i) high ionic conductivity; (ii) high lithium-ion transference number (LTN); (iii) good interfacial contacts with two electrodes; (iv) chemical stability as well as wide electrochemical and thermal windows; (v) mechanical stability and flexibility.…”

Lithium and Lithium-Ion Batteries: Challenges and Prospects

“…Due to their high thermal stability and low volatility (thus low flammability), combined with a good ionic conductivity, they are presently viewed as the electrolyte media that can consistently enhance battery safety. 5,6 Other choices are polymer, e.g., mixture of a lithium salt and poly(ethylene oxide) PEO or crystalline (still under development) solid membranes. Many excellent reviews reporting the proprieties of these advanced electrolytes are available in the literature, 5-8 hence they will not further discussed here.…”

Poly(vinyl chloride) Ionic Liquid Polymer Electrolyte Based on Bis(fluorosulfonyl)Amide for Sodium Secondary Batteries

“…As a type of gel polymer electrolytes (GPE), the resulting "ionic liquid polymer electrolytes (ILPEs)" consists of ILs, the host polymer, and another component for electrochemical reactions (e.g alkali metal salt). 13,14 In ILPE, it is assumed that the IL phase is trapped within the polymer matrix, forming a self-standing polymer electrolyte with the ions moving in the liquid phase. The advantages of ILPE are high processability, high flexibility, and high dimensional stability that lead to the elimination of the separator.…”

“…Sodium iron pyrophosphate, (Na 2 FeP 2 O 7 theoretical capacity: 97 mAh g −1 ), which is composed of naturally abundant elements Na, Fe and P is an attractive positive electrode material with three-dimensional diffusion path of Na + . [34][35][36][37][38] Particularly, it is known to provide high rate performance in the IL system of Na 40 Recently, another group tested PVC as a host polymer for two types of phosphonium ILs, [P 14,6,6,6 ][Cl] and [P 14,6,6,6 ][NTf 2 ] (P 14,6,6,6 + = trihexyltetradecylphosphonium cation), 41 and characterized the chemical, morphological, thermomechanical, and electric properties of the resulting ILPE. The influence of ionicity of the phosphonium IL on the ionic conductivity of the PVC-based electrolyte and the thermomechanical properties of PVC was also reported in the same study.…”