Excellent Cyclic and Rate Performances of SiO/C/Graphite Composites as Li-Ion Battery Anode

Abstract

The SiO-based composites containing different carbon structures were prepared from asphalt and graphite by the milling, spray drying, and pyrolysis. In the obtained near-spherical composite particles, the refined amorphous SiO plates, which are coated with an amorphous carbon layer, are aggregated with the binding of graphite sheets. The SiO/C/Graphite composites present a maximum initial charge capacity of 963 mAh g −1 at 100 mA g −1 , excellent cyclic stability (∼950 mAh g −1 over 100 cycles), and rate capability with the charge capacity of 670 mAh g −1 at 1,000 mA g −1 . This significant improvement of electrochemical performances in comparison with pristine SiO or SiO/C composite is attributed to the unique microstructure, in which both the graphite sheets and amorphous carbon coating could enhance the conductivity of SiO and buffer the volume change of SiO. The higher pyrolysis temperature causes the denser spherical microstructure and better cycle life. Our work demonstrates the potential of this SiO/C/Graphite composite for high capacity anode of LIBs.

Biomass‐Derived Hierarchically Porous (Nitrogen, Phosphorus) Co‐Doped SiOx/C Composite Nanosheet Architectures for Superior Lithium Storage and Ultra‐Long Cycle Performance

“…The deconvoluted components around 101.68, 102.09, 102.54 and 103.03 eV revealed the co-existence of multivalent silicon such as Si + , SiO 1.5 (Si 3 + ), SiO 2.0 C 2.0 and SiO 2.0 (Si 4 + ). [19,21] For N/P-SiO x /C-NSs-1000-5h, the relative percentages of Si + , SiO 1.5 (Si 3 + ), SiO 2.0 C 2.0 and SiO 2.0 (Si 4 + ) components are estimated to be 18.7 %, 31.82 %, 33.71 % and 15.8 %, respectively. The typical peaks of SiÀ O (532.8 eV) and OÀ SiÀ O (532.2 eV) were also confirmed by the O 1s spectra (Figure 3d).…”

“…For N/P-SiO x /C-NSs-900-5h, an obvious weight loss from 180 °C to 220 °C could be attributed to the evaporation of the adsorbed organics and/or super polymers at the surfaces and interfaces. [12,19,35] Above 470 °C, the almost unchanged TG curve was observed, suggesting the complete decomposition of carbon and the SiO x remanants of about 89 wt %. For the catkin precursors, the weight loss is over 85 % from 100 °C to 600 °C, indicating the full removal of carbonaceous components and organics and the retaining of remanent inorganic silicon phases over 600 °C.…”

“…Despite somewhat capacity decrease by oxidization, SiO x could still retain theoretical lithium-storage capacities from 2200 to 3580 mAh g À 1 with much mitigated volume changes of about 200 % and extended cycling life, which is therefore taken as the most promising candidates for Si-based anode materials. [17][18][19] On one side, the poor intrinsic conductivity (6.7 × 10 À 4 S cm À 2 ) gives rise to the sluggish formation kinetics of LiÀ O and LiÀ Si upon charge/ discharge which is responsible for large initial irreversible capacity, low initial coulombic efficiency, undoubtedly unfavorable for rate capability. Fortunately, on the other side, LiO 2 could form on the periphery of Si-based particles to construct stable solid electrolyte interfaces (SEI) and buffer the volumetric changes, which should be favorable for cycling performance.…”

“…Fortunately, on the other side, LiO 2 could form on the periphery of Si-based particles to construct stable solid electrolyte interfaces (SEI) and buffer the volumetric changes, which should be favorable for cycling performance. [19][20][21] Therefore, nanostructuring and construction of protective layers are expected to be capable of improving rate capability of and prolonging cycle lifetime of SiO x anodes in terms of shortening of Li + transport and reaction pathways, stress relaxation and surface protection. SiO x nanostructures including nanoparticles, nanospheres, nanowires, nanotubes and even various porous two-dimensional structures have been found capable of minimizing the mechanical strains of reactions caused by the volume changes.…”

Зависимость электрохимических параметров композитных SiO/C-анодов для литий-ионных аккумуляторов от состава и температуры синтеза

“…Проблема изменения объема в случае SiO x не такая серьезная, как для Si, однако ею также нельзя пренебречь. Для решения данных проблем были разработаны различные стратегии, такие как создание композитов, среди которых особое внимание уделяется углеродным композитам SiO x /C [2, [13][14][15][16][17][18].…”