Abstract
To improve the thermal shrinkage and ionic conductivity of the separator for lithium-ion batteries, adding carboxylic titanium dioxide nanofiber materials into the matrix is proposed as an effective strategy. In this regard, a poly(vinylidene fluoride-hexafluoro propylene)/dibutyl phthalate/carboxylic titanium dioxide (PVDF-HFP/DBP/C-TiO2) composite separator is prepared with the phase inversion method. When the content of TiO2 nanofibers reaches 5%, the electrochemical performance of the battery and ion conductivity of the separator are optimal. The PVDF-HFP/DBP/C-TiO2 (5%) composite separator shows about 55.5% of porosity and 277.9% of electrolyte uptake. The PVDF-HFP/DBP/C-TiO2 (5%) composite separator has a superior ionic conductivity of 1.26 × 10 −3 S cm−1 and lower interface impedance at room temperature, which brings about better cycle and rate performance. In addition, the cell assembled with a PVDF-HFP/DBP/C-TiO2 separator can be charged or discharged normally and has an outstanding discharge capacity of about 150 mAh g−1 at 110 °C. The battery assembled with the PVDF-HFP/DBP/C-TiO2 composite separator exhibits excellent electrochemical performance under high and room temperature environments.
Highlights
Lithium-ion battery (LIB) is the most promising power source for electronic devices because of its potential to be lightweight, high energy storage capability, long cycle life and pollution-free [1,2,3].because of the frequent mobile phone explosions and computer burning incidents recently, the safety problem of lithium-ion batteries has attracted widespread attention, which severely hinders the application of lithium-ion batteries in daily life [4,5].A complete lithium-ion battery is composed of an anode, an electrolyte, a separator, and a cathode
As presented in Figure uniformly distributed in PVDF-HFP/dibutyl phthalate (DBP)/C-TiO2 composite separators, and the pore size is 2–5 μm
The TiO2 nanofibers can improve the thermal stability of the separator
Summary
Lithium-ion battery (LIB) is the most promising power source for electronic devices because of its potential to be lightweight, high energy storage capability, long cycle life and pollution-free [1,2,3].because of the frequent mobile phone explosions and computer burning incidents recently, the safety problem of lithium-ion batteries has attracted widespread attention, which severely hinders the application of lithium-ion batteries in daily life [4,5].A complete lithium-ion battery is composed of an anode, an electrolyte, a separator, and a cathode. The separator has a great electrical insulation performance to prevent internal short-circuiting and is the medium for lithium-ion transport [6]. Polyethylene (PE) and polypropylene (PP) are the widely used commercialized separators in lithium-ion batteries at present, owing to their excellent mechanical strength and chemical stability [7,8]. PE and PP separators are especially prone to heat shrinkage at high temperatures, which has raised serious internal short-circuiting and safety problems [9]. To overcome these drawbacks, Fu et al [10] and Yoo et al [11] proposed coating SiO2 nanoparticles on the surface of a commercial separator to enhance its thermal stability
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