N-Doped gel-structures for construction of long cycling Si anodes at high current densities for high performance lithium-ion batteries

Abstract

Si-based N-doped gel-structures enable long-term cycling at high current densities for high performance lithium-ion batteriy anodes.

Control of Graphene Heteroatoms in a Microball Si@Graphene Composite Anode for High-Energy-Density Lithium-Ion Full Cells

“…42,43 The XPS C 1s spectra of Si@ECGB, Si@H2-ECGB, and Si@N-ECGB are displayed in Figure S7, indicating the bonding states of CC/C−C (∼284 eV), CO (∼287 eV), and O−CO (∼289 eV). 24,44 Moreover, the functionalization and reduction process affected the existing new peak at 285 eV (C−OH) 44 for Si@H2-ECGB and 285.7 eV (C− N) 29,31 for Si@N-ECGB. Table S2 and Figure S7 display the detailed spectrum binding energies of Si@ECGB, Si@H2-ECGB, and Si@N-ECGB.…”

“…The postannealing treatment of graphene with NH 3 and H 2 reactive gases was found to improve the CE and the reversible capacity; this behavior was attributed to the N-doped graphene forming defect sites (N species) and additional vacancies on the edges and in the basal planes, thus accommodating additional Li-ions and increasing the reversible capacity, which is consistent with the literature. 29,33 The high ICE of Si@N-ECGB indicates the stable formation of SEI, where the graphene wrapped Si serves as a stable SEI and thus avoid excessive electrolyte decomposition and the increased electrical conductivity help to facilitates the Li + ions pathway. 24,51,52 The rate performance of active materials was evaluated at various current densities of 0.2, 0.5, 1, 2, 3, and 5 A/g.…”

“…27 Moreover, Si@N-graphene processed with PPY as the nitrogen source and glucose as the carbon additive (complex fabrication) reached a first discharge capacity that was more than the theoretical discharge capacity (∼5000 mAh/g), but the CE decreased due to the increase in the charge transfer resistance. 29 The urea as a nitrogen source was found to promote the N-doping of Si@graphene during the postannealing treatment, which reached a low first discharge of 1712 mAh/g and a 71.5% CE. 31 Therefore, the previously reported strategies for preparing Si@N-doped graphene as a composite anode for LIBs had the limitation of being costeffective, scalable, and facile.…”

“…In addition, functionalized graphene with nitrogen doping (N doping) is attracting intense attention in Si@graphene composites for LIB anodes, from which N-doped sites were reported to increase the electrical conductivity while maintaining the rate performance and stability. It was reported that N-based precursors, such as polydopamine, melamine-formaldehyde, , polyaniline (PANI), polypyrrole (PPY), , and urea, − could be selected as efficient dopants for preparing composite anodes though the assembly of Si and graphene. A post-treatment (hydrothermal, annealing, microwave, or arc-discharge routes) with a mixture of N-based materials (PANI, PPY, urea, melamine) was reported to form N-doped nanocarbons.…”

“…The disadvantage is the complexity and the fact that it is a time-consuming process . Moreover, Si@N-graphene processed with PPY as the nitrogen source and glucose as the carbon additive (complex fabrication) reached a first discharge capacity that was more than the theoretical discharge capacity (∼5000 mAh/g), but the CE decreased due to the increase in the charge transfer resistance . The urea as a nitrogen source was found to promote the N-doping of Si@graphene during the postannealing treatment, which reached a low first discharge of 1712 mAh/g and a 71.5% CE .…”