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

The present studyreports the promising potential of waste hemp-hurd-derivedcarbons as anodes in sodium-ion batteries (SIBs). Carbons were producedthrough an easily scalable process consisting of pyrolysis of rawbiomass at 500 degrees C followed by mild chemical activation of theresulting char through wet impregnation with K2CO3 and subsequent heating of the solid phase (after filtration anddrying) up to 700 or 800 degrees C under nitrogen. The best electrochemicalperformance was observed for the hard carbon activated at a char-K2CO3 mass ratio of 1:4 and heated up to 800 degrees C,which exhibited an excellent initial coulombic efficiency (73%) andachieved reversible charge capacities of 267 and 79 mAh g(-1) at 0.03 and 1 A g(-1), respectively. This materialalso exhibited an impressive cyclic stability and rate capability,with a capacity retention of 96% after 300 cycles at a current densityof 2 A g(-1). This more than satisfactory performancecould be related to the textural and structural features of the hardcarbon, which include moderate interconnected microporosity (withpore sizes below 1 nm), an appropriate concentration of defects inthe carbon structure, relatively large interplanar distances, anda certain number of closed pores.

Automated summary

The study focuses on the potential application of waste hemp-hurd-derived carbons as anodes in sodium-ion batteries. The carbons were produced through a scalable process involving pyrolysis of biomass, chemical activation, and heating. The best performing carbon material exhibited excellent initial coulombic efficiency, reversible charge capacities, cyclic stability, and rate capability, which can be attributed to its unique textural and structural features.