Single‐Ion Conducting Electrolyte Based on Electrospun Nanofibers for High‐Performance Lithium Batteries

Abstract

Herein, a novel electrospun single‐ion conducting polymer electrolyte (SIPE) composed of nanoscale mixed poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) and lithium poly(4,4′‐diaminodiphenylsulfone, bis(4‐carbonyl benzene sulfonyl)imide) (LiPSI) is reported, which simultaneously overcomes the drawbacks of the polyolefin‐based separator (low porosity and poor electrolyte wettability and thermal dimensional stability) and the LiPF6 salt (poor thermal stability and moisture sensitivity). The electrospun nanofiber membrane (es‐PVPSI) has high porosity and appropriate mechanical strength. The fully aromatic polyamide backbone enables high thermal dimensional stability of es‐PVPSI membrane even at 300 °C, while the high polarity and high porosity ensures fast electrolyte wetting. Impregnation of the membrane with the ethylene carbonate (EC)/dimethyl carbonate (DMC) (v:v = 1:1) solvent mixture yields a SIPE offering wide electrochemical stability, good ionic conductivity, and high lithium‐ion transference number. Based on the above‐mentioned merits, Li/LiFePO4 cells using such a SIPE exhibit excellent rate capacity and outstanding electrochemical stability for 1000 cycles at least, indicating that such an electrolyte can replace the conventional liquid electrolyte–polyolefin combination in lithium ion batteries (LIBs). In addition, the long‐term stripping–plating cycling test coupled with scanning electron microscope (SEM) images of lithium foil clearly confirms that the es‐PVPSI membrane is capable of suppressing lithium dendrite growth, which is fundamental for its use in high‐energy Li metal batteries.

Decoupling segmental relaxation and ionic conductivity for lithium-ion polymer electrolytes

“…Similarly, Qin et al 133 synthesized and investigated polyborate-based electrolytes offering high ionic conductivity (1.8 × 10 −4 S cm −1 at 30°C) upon incorporation of a mixture of EC and DMC. Comparable results were obtained by Li et al 134 for the electrospun polyIJdiaminodiphenylsulfone)-type electrolyte. Noteworthy, however, all these systems provide Li + transference numbers (t + ) below 0.9 and require the incorporation of additional polymers like highly dielectric polyIJvinylidene difluoride) (PVdF) or its hexafluoropropylene-copolymer to realize suitable mechanical properties.…”

“…Nonetheless, one severe constraint remained: the electrochemical (in-)stability towards oxidation, limiting the application of such polymer electrolytes to LiFePO 4 as the cathode active material. [131][132][133][134][135] This limitation has been overcome only very recently by Nguyen et al, 136 who synthesized multi-block co-polyIJarylene ether sulfone) single-ion conductors based on alternating ionophobic and ionophilic blocks. The resulting films are self-standing and nanophase-separated.…”

Rechargeable Battery Electrolytes Capable of Operating over Wide Temperature Windows and Delivering High Safety

“…[257] Zhang et al reported that FEC is firstly reduced by Li metal in an electrolyte composed of LiPF 6 and EC/DEC. [258,259] Both the reduction of LiFSI and FEC led to the formation of a LiF-rich layer, which effectively improved the battery performance. [257][258][259] To make LT batteries, it is critical to design electrolyte|electrode interfaces characterized by a low impedance.…”

“…[258,259] Both the reduction of LiFSI and FEC led to the formation of a LiF-rich layer, which effectively improved the battery performance. [257][258][259] To make LT batteries, it is critical to design electrolyte|electrode interfaces characterized by a low impedance. Introducing Li salts that form ionically conductive SEIs may be conducive to that.…”

Preparation of polymer electrolyte membranes based on poly(phenylene oxide) with different side chain lengths of phosphonic acid

“…The electrochemical devices including fuel cells, secondary battery,, and supercapacitor become attractive because they are sustainable and eco‐friendly. Especially the fuel cells are high‐energy conversion efficiency devices with great prospects for future energy needs in view of zero emission of pollutants.…”