Effect of Fluorine Content on the Electrochemical Properties of PVDF-Derived Carbons for Lithium Ion Battery

Abstract

The carbon materials prepared by PVDF carbonization at different temperatures have similar BET surface area and pores volume. The content of fluorine in the carbons decreased with the carbonization temperature from 1.46% (atm %) at 600°C to 0.18 %( atm %) at 1000°C. The first cycle specific capacity and the initial coulombic efficiency decreases with the decrease of fluorine content in the samples. The first cycle discharge capacity decreased from 982 mAh/ g at 600°C to 752 mAh/ g at 1000°C and the initial coulombic efficiency decreased from 31.8% at 600°C to 24% at 1000°C. It is believed that fluorine contained in the carbon materials has a positive effect to improve the electrochemical properties as anode materials for Li-ion batteries.

Chemical and Morphological Transition of Poly(acrylonitrile)/Poly(vinylidene Fluoride) Blend Nanofibers during Oxidative Stabilization and Incipient Carbonization

“…It can therefore be assumed that remaining fluorine compounds are mainly located on the fiber surface.As the carbonization temperature increases, a steady loss of fluorine content would be expected. Shi et al confirmed this at higher carbonization temperatures for pure PVDF between 600 and 1000 • C [62].…”

“…It can therefore be assumed that remaining fluorine compounds are mainly located on the fiber surface.As the carbonization temperature increases, a steady loss of fluorine content would be expected. Shi et al confirmed this at higher carbonization temperatures for pure PVDF between 600 and 1000 °C [62]. Since the sensitivity of EDX spectroscopy is not well suited for the analysis of light elements [93], a quantitative evaluation of the spectra shown in Figure 8 is probably not reliable.…”

“…Due to its good electrochemical stability and affinity to electrolyte solutions, poly(vinylidene fluoride) (PVDF) has recently received significant attention for its potential as a precursor for CNFs and their potential application in lithium-ion batteries [ 59 , 60 , 61 , 62 ]. While Yang et al emphasized the need for low temperature chemical stabilization by dehydrofluorination for the subsequent carbonization of PVDF [ 61 ], other groups have shown that carbonization under a nitrogen atmosphere is possible without additional stabilization [ 59 , 63 , 64 ], suggesting that carbonizing PAN/PVDF may enable creating carbon fibers combining the advantages of both materials.…”