Abstract
Electrospun nanofiber membranes have been extensively studied as separators in Li-ion batteries due to their large porosity, unique pore structure, and high electrolyte uptake. However, the electrospinning process has some serious drawbacks, such as low spinning rate and high production cost. The centrifugal spinning technique can be used as a fast, cost-effective and safe technique to fabricate high-performance fiber-based separators. In this work, polymethylmethacrylate (PMMA)/polyacrylonitrile (PAN) membranes with different blend ratios were produced via centrifugal spinning and characterized by using different electrochemical techniques for use as separators in Li-ion batteries. Compared with commercial microporous polyolefin membrane, centrifugally-spun PMMA/PAN membranes had larger ionic conductivity, higher electrochemical oxidation limit, and lower interfacial resistance with lithium. Centrifugally-spun PMMA/PAN membrane separators were assembled into Li/LiFePO4 cells and these cells delivered high capacities and exhibited good cycling performance at room temperature. In addition, cells using centrifugally-spun PMMA/PAN membrane separators showed superior C-rate performance compared to those using microporous polypropylene (PP) membranes. It is, therefore, demonstrated that centrifugally-spun PMMA/PAN membranes are promising separator candidate for high-performance Li-ion batteries.
Highlights
Li-ion batteries have been widely used in many electronic devices, including mobile phones, laptop computers and digital cameras, because of their high energy density, large operational voltage, long cycling life, and low self-discharge rate [1,2]
The morphology of centrifugally-spun PMMA and PMMA/PAN membranes was studied by using a JEOL JSM-6400F field-emission scanning electron microscope (FESEM) (Bromont, QC, Canada)
The morphology of membrane separators affects the electrochemical properties of Li-ion cells by influencing the ion transport and conductivity behavior
Summary
Li-ion batteries have been widely used in many electronic devices, including mobile phones, laptop computers and digital cameras, because of their high energy density, large operational voltage, long cycling life, and low self-discharge rate [1,2]. Continuous nanosized polymer fibers are produced through the action of an external electric field imposed on a polymer solution [9,10,11] Enhanced electrochemical properties such as higher C-rate capability, better cycling performance and lower cell resistance have been reported for Li-ion cells using electrospun nanofiber-based separators [12,13]. Electrospinning process has some serious drawbacks such as low spinning rate and high production cost, which hinder the practical use of electrospun nanofiber separators in Li-ion batteries [14]. Considering the expensive processing of commercial microporous separators and electrospun separators, centrifugally-spun nanofiber separators may have a cost advantage due to the simplicity and high speed of this technique, and have the potential to decrease the overall cost of Li-ion batteries. PMMA/PAN membranes are promising separator candidate for high-performance Li-ion batteries
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