A Heat Resistant and Flame-Retardant Polysulfonamide/Polypropylene Composite Nonwoven for High Performance Lithium Ion Battery Separator

Abstract

A heat resistant and flame-retardant polysulfonamide/polypropylene composite nonwoven has been developed and exploited as an advanced separator for high performance lithium ion battery via melt-blown spinning followed by a phase-inversion process. It was manifested that such composite nonwoven exhibited improved flame retardance, superior thermal resistance and better electrolyte wettability as compared to commercialized polypropylene separator. It was also demonstrated that the lithium cobalt oxide (LiCoO 2 )/graphite cells employing the composite separator possessed better rate capability and superior cycling stability than those of polypropylene separator. Furthermore, this study verified the beneficial impact of polysulfonamide/polypropylene composite separator with respect to commercial polypropylene separator on cycle performance of lithium iron phosphate (LiFePO 4 )/lithium (Li) cells even at an elevated temperature of 120 • C. These fascinating results suggest that such composite nonwoven is promising separator for high performance lithium ion battery. Lithium ion battery (LIB) is considered to be the most promising technology for electric vehicles and energy storage systems due to its high-energy density, high-specific energy, low self-discharge rate, and long lifetime cycle.1-5 Among the components in lithium ion battery, the separator is a critical component for battery performance and also crucial for battery safety. The separator separates positive electrode and negative electrode while permitting the rapid diffusion of lithium ions through electrolyte.6,7 Microporous polyolefin-based separators, such as polyethylene and polypropylene membranes, have been commercially used as major separators for LIB because of satisfactory mechanical property, excellent chemical stability and good thermal shutdown properties. [8][9][10] The thermal shutdown property of the microporous separators could cut off the thermal runaway at the shutdown temperature.6 However, the microporous polyolefin separators often suffered from severe thermal shrinkage above melting temperature when the elevated temperature kept a little long time, which could cause direct contact between cathode and anode and finally result in short circuit of lithium battery.11 Meanwhile, the microporous polyolefin separators have been proven to cause poor electrolyte wettability problems, which lead to an increase in cell resistance and would restrict the battery performance.12,13 Tremendous efforts have been made to improve the overall properties of commercial polyolefin separators.14-17 One strategy was to incorporate inorganic nanoparticles into microporous polyethylene membrane (PE) or polypropylene membrane (PP) and the other one was to coat high performance polymers onto commercial separator surface. As a matter of fact, ceramic nanoparticles coating suffered from insufficient adhesion to polymer matrix, which could lead to the particles detached from separators' surface and generate a non-uniform current density across the electrodes during c...

Novel Core–Shell PS‐co‐PBA@SiO2 Nanoparticles Coated on PP Separator as “Thermal Shutdown Switch” for High Safety Lithium‐Ion Batteries

“…Figure a shows the first charge–discharge curves of the separators based on coated separator at 0.5 C with voltage range from 2.75 to 4.2 V. The typical electrochemical pseudoplateaus for LiFePO 4 (3.5 V for charge and 3.4 V for discharge) are observed in Figure a. It depends on oxidation and reduction potential for LiFePO 4 . The cell based on coated separator shows a reversible capacity of 145 mAh g −1 for ambient temperature and enhanced capacity (150 mAh g −1 ) for elevated temperature, which is attributed to the accelerated kinetics of lithium insertion reaction at elevated temperature.…”

Fabrication of co‐PVDF/modacrylic/SiO2 nanofibrous membrane: Composite separator for safe and high performance lithium‐ion batteries

“…As much as the safety of a separator is in tandem with the dimensional stability, the flame retarding property further emphasize the safety of LIB 61 . Figure 4 shows the combustion test results of different membranes.…”

“…Results show PAN‐based nanofibrous membrane caught fire easily and burst into flames very rapidly, while PP‐based membrane shrunk immediately. These observations are related to the poor flame retarding property of both PAN and PP and the low melting point of PP 8,25,61 . Though 100:0 membrane shrinks severely, it seems to be more resistive to fire compared to PAN membrane.…”

Re‐weighted random series path integral simulations of molecular clusters: Applications to lithium solvated by a mixed Stockmayer cluster

“…Even though the body of knowledge gathered to date on clusters is vast, we find surprisingly little work dedicated to the study of Stockmayer and ion‐Stockmayer clusters in the literature. The present goals are of fundamental importance for the research and development of lithium ion batteries, as a practical application. Lithium ion batteries are complex bulk systems, and their direct simulations will likely require more realistic models to extend the scope of the present investigation.…”