Impact of biomass inorganic impurities on hard carbon properties and performance in Na-ion batteries

Abstract

Biomass waste recently emerged as efficient precursors for hard carbon anode preparation for Na-ion batteries. Despite their very complex microstructure (organic/inorganic) there is a lack of knowledge about their impact on carbon formation. In this paper, the influence of inorganic impurities of three raw local biomass wastes (asparagus, grape and potato) on the hard carbon properties and on their electrochemical performance is investigated, by performing a washing step either before or after the thermal treatment (TT) at 1300 °C. When washing was done after the TT (with HCl), most of crystalline inorganic impurities (K, Ca, Si, Mg-based compounds) could be significantly removed. This triggered the increase of ultramicroporosity along with mesoporosity formation and graphite interlayer space (d002) contraction. Such observations are less pronounced on grape derived carbon due to the inorganic's catalytic induced local graphitization during pyrolysis. The oxygen content in the pristine carbons was high, owing to the presence of inorganic metal oxides and carbonates, and could be diminished after washing along with the amount of defects. Thus, the carbon content and the electronic conductivity of the materials were enhanced. The electrochemical performance improvement after washing was limited since the positive effect brought by impurities removal was negatively compensated by the changes occurring in the materials, particularly the increase in the specific surface area. Diffrently, the washing done before the TT (with water) induced only fewer changes on the materials porosity and structure and slightly improved capacity (from 215 to 230 mAh g −1). Furthermore, higher pyrolysis temperature (1400 °C) on washed HCs afforded a better reversible capacity up to 280 mAh g −1. This comprehensive study opens the door for green and mild synthesis approach to be further explored for sustainable fabrication of hard carbon for Na-ion batteries.

Co3O4 Nanoparticles Embedded in Mesoporous Carbon for Supercapacitor Applications

“…The latter behavior has been cited elsewhere as EDL capacitor behavior, ,, which can be explained by the increased porosity yielding in a faster diffusion and the higher conductivity of the carbon. The electrochemical impedance spectroscopy (EIS) has been used to determine the resistance and, subsequently, to calculate the conductivity of the materials (Table and Figure f). An increase trend of the conductivity with the pyrolysis temperature can be observed.…”

Hard Carbon Derived from Avocado Peels as a High-Capacity, High-Performance Anode Material for Sodium-Ion Batteries

“…As indicated by the arrow in Figure 2 (a), the diffraction peak of the (002) crystal plane shifted slightly to a higher angle, which signifies that the increase in temperature resulted in decreased spacing between the graphite layers, which has been observed by other hard carbon studies. [24][25][26] This finding was confirmed by calculating d 002 with the Bragg formula. HC-900 and HC-1100 showed graphene interlayer distances of 4.07 and 3.95 Å, respectively, both greater than the minimum interlayer space of 3.7 Å necessary for Na + insertion in carbon-based materials.…”

“…evaluated the effect of natural impurities in biomass-derived hard carbon as anode materials. 24 The maximum capacity achieved was 214 mAh/g at a rate of 37.…”

Tannin-based hard carbons as high-performance anode materials for sodium-ion batteries

“…Moreover, they are inexpensive and easy to synthesize from many carbonaceous precursors, mainly oxygen-rich molecules and polymers [36] such as, for example, sucrose [5,38,39], glucose [8,26,40], cellulose [6,33,41,42], lignin [2,43], phenolic resins [44][45][46][47][48] or pre-oxidized pitch [34,45,49]. Among all the precursors of hard carbons, those derived from biomass are of great interest lately, such as lignocellulosic biomass and fruit wastes [36,[50][51][52][53][54][55][56][57]. About 10 to 15 billion tons of biomass waste are formed worldwide each year.…”