A Novel Silicon/Phosphorus Co-Flame Retardant Polymer Electrolyte for High-Safety All-Solid-State Lithium Ion Batteries

Abstract

Developing a solid polymer electrolyte with superior flame retardancy and lithium-ion transportation properties is still a challenge. Herein, an intrinsic silicon/phosphorus co-flame retardant polymer solid electrolyte was prepared by using polyethylene glycol (PEG) co-polymerized with silicon and phosphorus-containing monomers. Due to the synergistic flame-retardant effect of silicon and phosphorus elements, this polymer electrolyte exhibits excellent thermal stability and flame resistance. Moreover, the ionic conductivity of the electrolyte at 25 °C is as high as 2.98 × 10−5 S/cm when the mass ratio of LiN(SO2CF3)2 (LiTFSI) and the prepared polymer electrolyte is 10:1. What is more, the LiFePO4/Li all-solid-state battery assembled with this solid electrolyte can work stably at a high temperature of 60 °C and exhibits a specific capacity of 129.2 mAh/g at 0.2 C after 100 cycles, providing a promising application prospect for high-safety lithium-ion batteries.

High-Performance Poly(vinylidene fluoride-hexafluoropropylene)-Based Composite Electrolytes with Excellent Interfacial Compatibility for Room-Temperature All-Solid-State Lithium Metal Batteries

“… 47 , 48 However, with the increase in lithium content to a certain extent, the solubilization effect is limited, and the electrostatic interactions between Li + and TFSI – become significant, which reduce the number of effective carriers and the ionic conductivity. 49 Moreover, lithium salt compresses the space for free chain segment movement of the polymer and reduces the film-forming ability to the extent that the slurry cannot form a film when the content of lithium salt is too high. Thus, when the optimal weight ratio was adjusted to PVDF-HFP:LiTFSI = 6:4 (labeled as GPE-a), the highest ionic conductivity of 3.28 × 10 –5 S·cm –1 was reached.…”

“…The concentration of lithium salt mainly affects the distribution of charge carriers and the long-range migration ability of lithium ions in the polymer. When the concentration of lithium salt is maintained at the low standard, it can be fully solubilized by PVDF-HFP, providing free lithium ions as charge carriers, which increases with lithium salt content. , However, with the increase in lithium content to a certain extent, the solubilization effect is limited, and the electrostatic interactions between Li + and TFSI – become significant, which reduce the number of effective carriers and the ionic conductivity . Moreover, lithium salt compresses the space for free chain segment movement of the polymer and reduces the film-forming ability to the extent that the slurry cannot form a film when the content of lithium salt is too high.…”

Recent Advances on Materials for Lithium-Ion Batteries

“…Flame retardancy is also an important and needed development in the SPE te nology, as it prevents the occurrence of incidents caused by short circuits, such as bu ing or explosion of the equipment. By doping the polymer matrix structure with ph phorous and silicon containing monomers, it is possible to increase the compatibil between the fillers and the matrix, which improves the overall stability even at hi temperatures, enhancing the flame retardant performance [263]. Flame retardancy is also an important and needed development in the SPE technology, as it prevents the occurrence of incidents caused by short circuits, such as burning or explosion of the equipment.…”

Quasi-Solid-State Ion-Conducting Arrays Composite Electrolytes with Fast Ion Transport Vertical-Aligned Interfaces for All-Weather Practical Lithium-Metal Batteries

“…Rechargeable solid-state batteries are at the forefront of the proposed storage devices for tomorrow's applications [3,4]. Solid-state electrolytes have several advantages compared with the liquid electrolytes traditionally used in commercial rechargeable batteries, such as wide electrochemical windows, no risk of flammability or leaking and good thermal stability [5][6][7]. In addition, many reports show that solid electrolytes could prevent lithium or other metal dendrite growth, thereby realizing the 'holy grail' of high-energy-density metal batteries [8].…”