Mitigation and In Situ Probing of Volume Expansion in Silicon/Graphene Hybrid Anodes for High‐Capacity, High‐Rate‐Capable Lithium‐Ion Batteries

Abstract

Internal macropores in silicon/graphene/graphene nanoribbon (Si/Gr/GNR) hybrid anodes by facile thermal removal of sacrificial polymer, polyvinyl alcohol (PVA), are incorporated, to mitigate the volume expansion of silicon and to increase the silicon utilization and rate capability of the anode. The resulting Si/Gr/GNR hybrid anodes give a high capacity of 1874 mAh g−1 at 0.1 C, based on total weight of the electrode including binder and carbon, as well as great capacity retention of above 800 mAh g−1 after 350 cycles at 0.3 C. The mitigation of volume expansion by carrying out in situ thickness change measurements of small pouch cells via a dilatometer is further demonstrated, exhibiting the saturation of volume expansion below 40% after 100 cycles due to the incorporation of the macropores. Moreover, Si/Gr/GNR anodes with pores exhibit superior rate capability, yielding 1,250 mAh g−1 at 2 C rate due to the effective network of graphene sheets and GNRs.

Ionic/Electronic Dual‐Conductor Coating Layer Fabrication Enabling High‐Performance Silicon Anode

“…The flat plateau observed at about 0.25 V can be attributed to the amorphous Si–Li reaction. [ 27 ] It is obvious that the polarization voltage of the Si@Li 4 SiO 4 /C/CNTs electrode is much smaller than the Si electrode. The rate capabilities of Si@Li 4 SiO 4 /C/CNTs and Si materials were evaluated from 0.1 to 2 A g −1 .…”

Robust Core–Shell Carbon-Coated Silicon-Based Composite Anode with Electrically Interconnected Spherical Framework for Lithium-Ion Battery

“…The Si nanoparticles, CNTs, GO nanoparticles, and carbon-coating layers contributed to the excellent electrochemical performance of the C-Si/CNT/GO composite as a LIB anode. The possible contributions are as follows: (a) the Si nanoparticles contributed to the high electrochemical capacity of the C-Si/CNT/GO composite; (b) the CNTs facilitated the formation of the electrical networks and spherical frameworks, depending on the dispersibility of the CNTs, and thus, the well-dispersed CNTs improved the electrical conductivity of the 3D architecture and provided sufficient buffer space for accommodating the volume expansion of the Si nanoparticles; (c) the GO nanoparticles enabled the formation of electrically conductive pathways and played a vital role in the formation of spherical morphology by the suspension of CNTs in the aqueous Si/ CNT/GO dispersion, which was promoted by the excellent sphere-forming ability of the GO nanoparticles during the spray-drying process [25,51]; and (d) furthermore, the carbon-coating layer improved the electrical conductivity and mechanical structural stability of the composite, prevented electrolyte permeation, and suppressed the side reactions and SEI formation [52]. Our study reveals that the electrically interconnected carbonaceous framework significantly enhances the buffering effect for volume expansion and the Li-ion diffusivity in the Si-based composite anode, which is associated with the robust framework and increased diffusion channels by synergistic effects of the uniformly dispersed CNTs and GO nanoparticles and the carbon-coating layers.…”

The Utilization of Carbon Nanotubes in Advanced Silicon – Carbon Anode Materials for Lithium-Ion Batteries

“…The composite anode of C-Si/CNT/GO (grapheme oxides) demonstrates exceptional electrochemical performance, exhibiting high specific charge and discharge capacities (2921 and 2395 mAhg −1 at 100 mAg −1 , respectively), prolonged cycle life (1542 mAh g −1 at 200 mAg −1 after 100 cycles, with a capacity retention of 64%), and high charge/discharge rates (1506 mAhg −1 at 6 Ag −1 ). The elements of the C-Si/CNT/GO composite anode synergistically enhance its electrochemical performance for LIB applications [18]. The silicon nanoparticles contribute to the high electrochemical capacity; the CNTs and GO facilitate the creation of electrical networks and spherical frameworks, thanks to the dispersibility of the CNTs, thereby improving the electrical conductivity of the 3D architecture and providing adequate buffer space to accommodate the volume expansion of the silicon nanoparticles.…”