Binder less-integrated freestanding carbon film derived from pitch as light weight and high-power anode for sodium-ion battery

Role of iron oxide in retarding the graphitization of de-oiled asphaltenes for amorphous carbon

The solvent deasphalting (SDA) process is widely recognized as a significant technology in processing inferior oil. However, de-oiled asphaltene (DOA), which accounts for about 30% of feedstocks, is not well utilized in conventional processing methods to date. Considering its complicated structure and high heteroatom and metal contents, DOA is suitable for preparing amorphous carbon. Herein, we obtained amorphous carbon from inferior de-oiled asphaltene through direct carbonization of a mixture of DOA and Fe2O3 and revealed the mechanism of iron oxide in retarding graphitization to increase the disordered structure content. After the addition of Fe2O3, XRD results showed that the content of amorphous carbon increased from 25.57% to 59.48%, and a higher defect degree could also be observed in Raman spectra, thus resulting in better electrochemical performance in Na-ion half-cells. As a coke core, Fe2O3 could accelerate the polycondensation of asphaltene molecules; meanwhile, oxygen species derived from Fe2O3 could capture excess H free radicals in the initial pyrolysis stage, which inhibited the formation of planar polycyclic aromatic molecules and weakened π-π interactions. Moreover, O atoms could embed into the carbon skeleton by reacting with DOA at higher temperatures, which could further twist and break the intact carbon layer. Both of the factors enhanced the proportion of amorphous carbon. This work not only provides a new understanding of controlling the carbonization process, but it also promotes the development of the SDA process.

Synthesis Strategies and Applications for Pitch-Based Anode: From Industrial By-Products to Power Sources

It is significant for saving energy to manufacture superb-property batteries. Carbon is one of the most competitive anode materials in batteries, but it is hard for commercial graphite anodes to meet the increasingly higher energy-storage requirements. Moreover, the price of other better-performing carbon materials (such as graphene) is much higher than graphite, which is not conducive to massive production. Pitch, the cheap by-product in the petroleum and coal industries, has high carbon content and yield, making it possible for commercialization. Developing pitch-based anodes can not only lower raw material costs but also realize the pitch's high value-added utilization. We comprehensively reviewed the latest synthesis strategies of pitch-derived materials and then introduced their application and research progress in lithium, sodium, and potassium ion batteries (LIBs, SIBs, and PIBs). Finally, we summarize and suggest the pitch's development trend for anodes and in other fields.

Designing Materials and Processes for Strong Polyacrylonitrile Precursor Fibers

Although polyacrylonitrile (PAN)-based carbon fibers have been successfully commercialized owing to their excellent material properties, their actual mechanical performance is still much lower than the theoretical values. Meanwhile, there is a growing demand for the use of superior carbon fibers. As such, many studies have been conducted to improve the mechanical performance of carbon fibers. Among the various approaches, designing a strong precursor fiber with a well-developed microstructure and morphology can constitute the most effective strategy to achieve superior performance. In this review, the efforts used to modulate materials, processing, and additives to deliver strong precursor fibers were thoroughly investigated. Our work demonstrates that the design of materials and processes is a fruitful pathway for the enhancement of the mechanical performance of carbon fibers.