Abstract
DCLR-P was prepared by direct coal liquefaction residue (DCLR) with ash removal. In the present experiments, mesocarbon microbeads (MCMBs) were prepared by co-carbonization of coal tar pitch (CTP) and DCLR-P. With the increase of DCLR-P content, the yield of MCMBs increased from 47.8% to 56.8%. At the same time, the particle sizes distribution of MCMBs was narrowed, resulting in the decrease of D90/D10 ratio from 154.88 to 6.53. The results showed that DCLR-P had a positive effect on the preparation of MCMBs. 1H-NMR, FTIR, SEM and XRD were used to analyze the mechanisms and characteristics of MCMBs prepared by co-carbonization of CTP and DCLR-P. The results showed that the Proton Donor Quality Index (PDQI) of DCLR-P was 13.32, significantly higher than that of CTP (0.83). This indicated that DCLR-P had more naphthenic structure than CTP, which leads to hydrogen transferring in polycondensation reaction. The aliphatic structure of DCLR-P can improve the solubility and fusibility of mesophase, thereby making the structure of MCMBs more structured. The microstructure of the graphitized MCMBs had a substantially parallel carbon layer useful for its electrical performance. The performance of graphitized MCMBs as a negative electrode material for Li-ion batteries was tested. The particle sizes, tap density, specific surface area and initial charge–discharge efficiency of graphitized MCMBs met the requirements of CMB-I in GB/T-24533-2009. However, the initial discharge capacity of graphitized MCMB was only 296.3 mA h g−1 due to the low degree of graphitization of MCMBs.
Highlights
Mesocarbon microbeads (MCMBs) have been recognized as an exceptional precursor of lithium ion battery anode materials due to its uniform size, excellent sphericity, homogeneous shrinkage and unique microstructure (Chang et al 1999; Alcantara et al 2000; Wang et al 2000; Hossain et al 2003; Imanishi et al 2008)
The results showed that direct coal liquefaction residue (DCLR)-P had a positive effect on the preparation of mesocarbon microbeads (MCMBs). 1H-NMR, Fourier transform infrared spectroscopy (FTIR), sizes distribution of MCMBs microscopy (SEM) and X-ray diffraction (XRD) were used to analyze the mechanisms and characteristics of MCMBs prepared by co-carbonization of coal tar pitch (CTP) and DCLR-P
The results showed that the Proton Donor Quality Index (PDQI) of DCLR-P was 13.32, significantly higher than that of CTP (0.83)
Summary
Mesocarbon microbeads (MCMBs) have been recognized as an exceptional precursor of lithium ion battery anode materials due to its uniform size, excellent sphericity, homogeneous shrinkage and unique microstructure (Chang et al 1999; Alcantara et al 2000; Wang et al 2000; Hossain et al 2003; Imanishi et al 2008). The physical effects showed that the additives did not react with polyaromatic hydrocarbons, only affecting the formation of MCMBs physically such as its shape and sizes. Direct coal liquefaction residue (DCLR) is one of the products in direct coal liquefaction process. It has the properties of high ash, high sulfur, and high aromatics. DCLR can be used to prepare high value-added carbon materials such as carbon foam (Xiao et al 2010), carbon fibers (Liu et al 2015), and MCMBs (Chang 2017). The MCMBs were prepared by CTP in the presence of DCLR, and the effects of DCLR on the formation and characteristics of MCMBs were studied
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