Electrospun Fluorinated Polyimide/Polyvinylidene Fluoride Composite Membranes with High Thermal Stability for Lithium Ion Battery Separator

Abstract

The separator with excellent mechanical and thermal properties are highly required for lithium ion batteries (LIBs). Therefore, it is crucial to develop novel nanofibrous membranes with enhanced mechanical strength and thermal stability. In this work, the fluorinated polyimide (FPI) was synthesized and blended with polyvinylidene fluoride (PVDF) to fabricate composite nanofibrous membranes (CNMs) via electrospinning method. Benefiting from the introduction of aromatic FPI, the prepared PVDF/FPI nanofibrous membranes were endowed with enhanced mechanical strength and thermal stability. When the FPI content increased from 0 to 30 wt%, the tensile strength of composite nanofibrous membranes enhanced from 1.57 to 2.30 MPa. Moreover, there are almost no dimensional shrinkage for the CNM-30 containing 30 wt% FPI after heat treatment at 160 °C for 1 h. Furthermore, the prepared CNMs show improved electrochemical performances in comparison with neat PVDF and commercial Celgard membranes. The electrolyte uptake and ionic conductivity of the CNMs could reach to 522.4% and 1.14 ms•cm −1 , respectively. The prepared CNMs could provide an innovative and promising approach for the development and design of high-performance separators.

Ion Flux Self-Regulation Strategy with a Volume-Responsive Separator for Lithium Metal Batteries

“…As one of the vital components of lithium batteries, the separator provides a physical barrier between the anode and cathode while allowing lithium-ion migration through the micropores when immersed in liquid electrolytes . The separator is mainly distributed into polyolefin porous membrane, nonwoven membrane, polymer gel electrolyte, and solid-state electrolyte. ,, However, there is no ideal separator suitable for all battery systems. After decades of development, the separator obtained shutdown function through a low melting layer, , with self-flame retardant ability via a core–shell design, and thermal-responsive feature utilizing self-polymerization .…”

“…17 The separator is mainly distributed into polyolefin porous membrane, nonwoven membrane, polymer gel electrolyte, and solid-state electrolyte. 13,18,19 However, there is no ideal separator suitable for all battery systems. After decades of development, the separator obtained shutdown function through a low melting layer, 20,21 with self-flame retardant ability via a core−shell design, 22 and thermal-responsive feature utilizing self-polymerization.…”

Cross-Linked and Rigid Polyimide Composite Foams with Prominent Fire Resistant, Thermal Insulating, and Wave-Transparent Properties

“…The morphology of fire-treated zones after burning was identified by SEM. As observed in Figure h, the cellular skeleton of PI-8 remains stable without any structural collapse, and only some thin cell walls were burned out and disappeared, demonstrating superior thermal stability of the cross-linked PI/GF composite foams …”

“…As observed in Figure 4h, the cellular skeleton of PI-8 remains stable without any structural collapse, and only some thin cell walls were burned out and disappeared, demonstrating superior thermal stability of the cross-linked PI/GF composite foams. 34 Thermal insulation and thermal management capacity of PI/ GF composite foams were also investigated in detail. Here, considering that the flexible PUI foam displays outstanding thermal insulation performance, it has been widely used in many high-tech fields such as aerospace and aviation industries as thermal insulating and acoustic absorbing materials.…”

Assembly: A Key Enabler for the Construction of Superior Silicon‐Based Anodes

“…Silicon, attributed to the low working potential (0.5 V vs Li/Li + ), high theoretical capacity (4200 mA h g –1 ) and the natural abundance, has become one of the most promising anode materials to replace graphite for high energy lithium‐ion batteries. [ 6 , 7 , 8 , 9 ] However, the born defects of silicon anodes, including inferior electrical conductivity, sluggish lithium‐ion diffusion coefficient and serious volume expansion (>300%) during lithium insertion and extraction, easily increase electrode internal stress which will result in pulverization of electrode and the formation of unstable solid electrolyte interfaces (SEI) film, leading to rapid capacity decay ( Figure 1 ). To overcome these obstacles, a series of effective measures have been taken.…”