Engineering Surface Oxygenated Functionalities on Commercial Carbon toward Ultrafast Sodium Storage in Ether-Based Electrolytes

Regulating the Pore Structure of Biomass-Derived Hard Carbon for an Advanced Sodium-Ion Battery

Biomass-derived hard carbon materials are attractive for sodium-ion batteries due to their abundance, sustainability, and cost-effectiveness. However, their widespread use is hindered by their limited specific capacity. Herein, a type of bamboo-derived hard carbon with adjustable pore structures is developed by employing a ball milling technique to modify the carbon chain length in the precursor. It is observed that the length of the carbon chain in the precursor can effectively control the rearrangement behavior of the carbon layers during the high-temperature carbonization process, resulting in diverse pore structures ranging from closed pores to open pores, which significantly impact the electrochemical properties. The optimized hard carbon with abundant closed pores exhibits a high specific capacity of 356 mAh g-1 at 20 mA g-1, surpassing that of bare hard carbon (243 mAh g-1) and hard carbon with abundant open pores (129 mAh g-1 at 20 mA g-1). However, the kinetic analysis reveals that hard carbon with open pores shows better sodium-ion diffusion kinetics, indicating that a balance between the closed and open pores should be considered. This research offers valuable insights into pore design and presents a promising approach for enhancing the performance of hard carbon anode materials derived from biomass precursors.

An investigation into the preparation of carbon black by partial oxidation of spent tyre pyrolysis oil

To promote the use of recycled waste materials as an industrial feedstock, this study examined the preparation of carbon black (CB) by partial oxidation of a spent tyre pyrolysis oil using a drop tube furnace. The effect of reaction temperature, the residence time of gas in the reactor and inlet gas oxygen concentration on the yield and properties of the CB were evaluated. The surface chemistry, chemical composition, morphological and thermal properties of the CB samples were characterised using XPS, EA, TEM, BET, and TGA, respectively. The CB yield increased with increasing reaction temperature but decreased as the residence time or oxygen concentration increases. The CB primarily consisted of C (90.5-98.6%) and O (0.9-7.4%), with small traces of S (<1%), Si (<1%) and H (<2%). Hydroxyl, carbonyl, and carboxyl are the key functional groups found on the CB surface, with the hydroxyl groups being dominant. The CB were highly graphitic with a lattice spacing in the range of 0.338-0.350 nm and had BET surface areas of 4-22 m²g^-1. The mean primary particle size ranged from 92 to 176 nm and decreased with increasing reaction temperature and oxygen concentration. The CB aggregate configuration became more complex with increasing reaction temperature, residence time and oxygen concentration. The results were not only comparable with commercial CB products from fossil fuel feedstocks but are expected to provide the needed motivation to move towards circular economy strategies, which have positive impacts from a sustainability perspective.