Pectin, Hemicellulose, or Lignin? Impact of the Biowaste Source on the Performance of Hard Carbons for Sodium‐Ion Batteries

Abstract

Hard carbons are currently the most widely used negative electrode materials in Na-ion batteries. This is due to their promising electrochemical performance with capacities of 200-300 mAh g and stable long-term cycling. However, an abundant and cheap carbon source is necessary in order to comply with the low-cost philosophy of Na-ion technology. Many biological or waste materials have been used to synthesize hard carbons but the impact of the precursors on the final properties of the anode material is not fully understood. In this study the impact of the biomass source on the structural and electrochemical properties of hard carbons is unraveled by using different, representative types of biomass as examples. The systematic structural and electrochemical investigation of hard carbons derived from different sources-namely corncobs, peanut shells, and waste apples, which are representative of hemicellulose-, lignin- and pectin-rich biomass, respectively-enables understanding and interlinking of the structural and electrochemical properties.

Impact of the Acid Treatment on Lignocellulosic Biomass Hard Carbon for Sodium‐Ion Battery Anodes

“…As am atter of the fact, the XRD pattern of LHC_0D presents several peaks attributable to the presence of impurities such as CaCO 3 and KCO 3 . [71] All three hard carbons show ap eak at about2 6.58,w hich is also observed for LHC_2W.P revious studies on carbon derived from peanut shells [57,72] and banana peels [40] also report ap eak occurring in the same position, and assigned it to graphite. Figure 2c compares the (0 02)r eflections of all materials, showingt hat their intensity increases with increasinga cid activation time.…”

“…[57] The SEM images in Figure 1r eveal the acid treatment impact on the morphology of the resulting hard carbon. Thec arbonizationw as performed at 1100 8C under Ar.A ccordingly, the samples are namedL HC_0D, LHC_1D, and LHC_6D,r espectively.F or comparison purposes, the earlier reported resultso btained from peanut shellss oaked for two weeks (LHC_2W) are also used in this manuscript.…”

“…[57] The SEM images in Figure 1r eveal the acid treatment impact on the morphology of the resulting hard carbon. [57] The different morphologies resulting from the variousa cid treatments can be explained by considering that peanuts hells are composed of different polymer components including lignin (27-40wt%), cellulose ( 34-45wt%), and hemicellulose, and other components including proteins and inorganic salts amongo thers. A6 -day acid treatment leads to the disappearance of the small particles, still detected in LHC_1D (Figure 1d), and to the resemblance with the morphology of the 2-week acid-treated sample (SEM images of LHC_2W are reported elsewhere).…”

“…[42,68,69] Morphological and structural analysis of the samples suggest the acid treatment to enable the achievemento fahigher degree of structuralo rder both at am icrometric level, as ob- Figure 2. [57] Property LHC_0D LHC_1D LHC_6DL HC_2W www.chemsuschem.org served by SEM, and at am olecular level, as suggested by Raman analysis. [57] Comparisons of Raman spectra(a), X-ray diffractionp atterns (b), and normalizedX RD patterns between a2 q range from 108 to 358 (c).…”

“…However,w ith longera cid treatments prior to carbonization,t he I D /I G ratio decreased to 1.20 (LHC_6D) and 0.98 (LHC_2W). [57] Comparisons of Raman spectra(a), X-ray diffractionp atterns (b), and normalizedX RD patterns between a2 q range from 108 to 358 (c). [42,68,69] Morphological and structural analysis of the samples suggest the acid treatment to enable the achievemento fahigher degree of structuralo rder both at am icrometric level, as ob- Figure 2.…”