Nanoporous carbons from hydrothermally treated biomass as anode materials for lithium ion batteries

High-Surface-Area Mesoporous Activated Carbon from Hemp Bast Fiber Using Hydrothermal Processing

“…It is generally believed that the KOH activation process of any carbon material enhances the pore structure and morphology with a substantial increase in specific surface area [14]. [18] -614 Orange peel [19] CO 2 618 Glucose [20] KOH 1197 Palm date seed [21] NaOH 1282 Desert shrub [22] ZnCl 2 1296 Rice husk [23] H 3 PO 4 1498 Hazelnut shell [24] KOH 1700 Glucose [25] KOH 1704 Sucrose [26] H 3 PO 4 2120 Glucose [26] NaOH 2129 Starch [27] KOH 2190 Rye straw [28] KOH 2200 Eucalyptus sawdust [29] KOH 2252 Corncobs [30] KOH 2300 Hemp bast fiber (this study) KOH 2425 Figure 1 provides the N 2 adsorption-desorption isotherms at −196 • C and pore size distributions of HAC, where HACs were prepared using different biochar-to-KOH ratios at a synthesis temperature of 390 • C. All the adsorption-desorption isotherms exhibit a type IV isotherm with a type IV hysteresis loop (according to IUPAC classification) in the relative pressure range from 0.4 to 1.0. Type IV isotherms are an indication of the existence of well-developed mesopores in the structure, whereas a type IV hysteresis loop indicates the formation of asymmetric, slit-shaped mesopores, attributable to rapid gas evolution and open channels [31].…”

Conjugated Microporous Polymer‐Derived Porous Hard Carbon as High‐Rate Long‐Life Anode Materials for Lithium Ion Batteries

“…[17] In most cases, however, it is difficult to obtain a porous carbon that fulfills such multivariable performance requirements, especially when using traditional materials such a gelatin, [17] sucrose, [18] polyacrylonitrile, [19] biomass, [20] and polypyrrole, [21] as carbon source. In particular, traditional synthesis methods involving the carbonization of low-vapor-pressure polymeric precursors 19,21] or natural sources [20] have their respective drawbacks, which are mostly associated with cross-linking reactions that proceed with concomitant char formation or uncontrolled vaporization during high-temperature pyrolysis.…”

“…[16] Therefore, it is important to prepare porous carbons with improved porosity. So far, a number of porous carbons have been prepared by using different methods such as hard templating, [17][18][19] hydrothermal carbonization, [20] and KOH treatment. [21] In addition, good rate capability and high capacities have been achieved by using these porous carbons as anode materials in LIB systems.…”

“…[17] In most cases, however, it is difficult to obtain a porous carbon that fulfills such multivariable performance requirements, especially when using traditional materials such a gelatin, [17] sucrose, [18] polyacrylonitrile, [19] biomass, [20] and polypyrrole, [21] as carbon source. In particular, traditional synthesis methods involving the carbonization of low-vapor-pressure polymeric precursors 19,21] or natural sources [20] have their respective drawbacks, which are mostly associated with cross-linking reactions that proceed with concomitant char formation or uncontrolled vaporization during high-temperature pyrolysis. [22] Conjugated microporous polymers (CMP) have received considerable research interest because of their 3D interlinked porous structure, large Brunauer-Emmett-Teller (BET) specific surface areas, and good chemical stability [23][24][25][26][27][28][29][30][31][32][33] with regard to potential applications for the selected adsorption of organic solvents [24] and gas adsorption.…”

“…The reversible capacity of 519.6 mA h g À1 is considerably higher than that of graphite and can compete with other porous carbons. [18,20] However, the capacity loss is too high (753.8 mA h g À1 ), which has been observed for many porous carbons, and is mainly attributable to the decomposition of electrolytes and the formation of a SEI on the surface of electrode materials. [21,[36][37][38] For the porous three-dimensional network structure of PHC-1, many mesopores and macropores could adsorb a large amount of electrolyte, which greatly enhances the contact between electrolyte and PHC-1 and thus the deposition of the SEI layer on the electrode surface.…”