Waste Hemp Hurd as a Sustainable Precursor for Affordable and High-Rate Hard Carbon-Based Anodes in Sodium-Ion Batteries

Abstract

The present study reports the promising potential of waste hemp-hurd-derived carbons as anodes in sodium-ion batteries (SIBs). Carbons were produced through an easily scalable process consisting of pyrolysis of raw biomass at 500 °C followed by mild chemical activation of the resulting char through wet impregnation with K2CO3 and subsequent heating of the solid phase (after filtration and drying) up to 700 or 800 °C under nitrogen. The best electrochemical performance was observed for the hard carbon activated at a char-K2CO3 mass ratio of 1:4 and heated up to 800 °C, which exhibited an excellent initial coulombic efficiency (73%) and achieved reversible charge capacities of 267 and 79 mAh g–1 at 0.03 and 1 A g–1, respectively. This material also exhibited an impressive cyclic stability and rate capability, with a capacity retention of 96% after 300 cycles at a current density of 2 A g–1. This more than satisfactory performance could be related to the textural and structural features of the hard carbon, which include moderate interconnected microporosity (with pore sizes below 1 nm), an appropriate concentration of defects in the carbon structure, relatively large interplanar distances, and a certain number of closed pores.

Intrinsically Nitrogen-Enriched Biomass-Derived Hard Carbon with Enhanced Performance as a Sodium-Ion Battery Anode

“…This is due to the diffusion is hindered by the sodium ion trapped into the closed pores that there is not enough path for the desorption. 35 Figure 8c represents the use of HCs in SIBs and their charge storage behavior during sodiation and desodiation processes. The obtained results were compared with the other biomassderived HC anodes and are presented in Table S2.…”

“…The values were decrease during discharge especially toward the fully desodiated state. This is due to the diffusion is hindered by the sodium ion trapped into the closed pores that there is not enough path for the desorption Figure c represents the use of HCs in SIBs and their charge storage behavior during sodiation and desodiation processes.…”

“…Nowadays, instead of using expensive inorganic materials, researchers have focused more on creating HC using materials derived from abundant biomass. For instance, materials like rice husk, banana peels, silk, apple biowaste, sucrose, peanut shells, pinecones, corn hubs, argan shells, cocoa pod husk, waste hemp hurd, sawdust waste, and mangosteen shells can be used to make HCs. ,− Utilizing biomass could save costs while also addressing pollution caused by burning an abundance of waste biomass. A high-capacity HC anode could also be used to increase the battery’s energy density.…”

Recent progress on hard carbon and other anode materials for sodium-ion batteries

“…Waste hemp hurd has been widely studied for different applications such as CO 2 absorption, additives in biocomposites, ultraviolet shielding film, and bioplastics [ [46] , [47] , [48] , [49] ]. In recent study, this material was also exploited for the hard carbon production where the end product was derived through the process of low temperature pyrolysis at 500 °C, followed by mild chemical activation of the resulting char through wet impregnation with K 2 CO 3 , and subsequent heating of the solid phase up to 700 or 800 °C under nitrogen [ 50 ]. The hard carbon activated at a char-K 2 CO 3 with mass ratio of 1:4 with subsequent pyrolysis at 800 °C demonstrated the best electrochemical performance, exhibiting an excellent initial coulombic efficiency of 73 % and achieving reversible charge capacities of 267 and 79 mAh/g at 0.03 and 1 A/g, respectively.…”