Vertically aligned Si@reduced graphene oxide frameworks for binder‐free high‐areal‐capacity Li‐ion battery anodes

Abstract

In this study, lamellar-structured, vertically aligned silicon@reduced graphene oxide frameworks (VA-Si@rGO) are developed for binder-free, high-arealcapacity lithium ion battery (LiB) anodes. First, SiO 2 /rGO frameworks with unidirectional pores are constructed via the gelation of SiO 2 /graphene oxide sol and subsequent freeze-casting. Afterwards, the sturdy constructed frameworks are maintained during a series of processes, namely magnesiothermic reduction, acid etching, and thermal carbon coating, which result in carboncoated VA-Si@rGO. The electrode exhibits a high specific capacity, reversibility, and cycle stability, which are attributed to its unique inner porous structure, high Si yield, and uniform carbon layers. A high areal capacity of approximately 9 mAh cm −2 could be achieved by increasing the initial sol concentration up to 23.5 wt%. Furthermore, even at a high current density of 3 mA cm −2 , the electrode delivered a high areal capacity of approximately 6 mAh cm −2 and exhibited excellent stability with a high capacity retention of 68% after the 150th cycle.

Polymer Electrolyte/Sulfur Double‐Shelled Anisotropic Reduced Graphene Oxide Lamellar Scaffold Enables Stable and High‐Loading Cathode for Quasi‐Solid‐State Lithium‐Sulfur Batteries

“…Thermal reduction of the VG foam was carried out at 800 °C for 2 h, and subsequently, the carbon coating process was performed for 1 h at the same temperature using acetone as the carbon source, to improve the electrical conductivity of the electrode. [ 35,36 ] All the thermal processes were carried out under an Ar/H 2 (95/5 sccm) flow. The obtained samples were punched into a disk with a diameter of 10 mm and denoted as VRG foam (VGCF/rGO foam).…”

“…First, we fabricated a 3D‐structured free‐standing electrode via the freeze‐casting method using rGO foam as the support and active sulfur as the current collector. [ 35,36 ] Freeze casting is a facile and cost‐effective method for fabricating porous 3D structures. When a homogeneously casted graphene oxide slurry is placed on a frozen substrate, the ice crystals grow upward from the bottom to the top of the slurry.…”

Synthesis of Si/Fe2O3-Anchored rGO Frameworks as High-Performance Anodes for Li-Ion Batteries

“…Graphene and reduced graphene oxide (rGO) with high electrical conductivity and high mechanical strength have been adopted in the design of Si-C anodes for LIBs to relieve the large stress caused by continuous charge-discharge cycles [27,28]. For example, vertically aligned Si@rGO frameworks were prepared by Park et al [29] through a series of processes including gelation, freeze-casting, magnesiothermic reduction, acid etching, and thermal carbon coating. Capacity retention of 68% could be obtained after 150 cycles.…”

Effect of rGO loading on the electrochemical performance of Li 22 Si 5 / rGO composite anodes for lithium‐ion batteries

“…12 On the other hand, carbonaceous materials such as graphite, graphene, and carbon nanotube act as matrix in the structure and they can buffer the volume change while they increase the conductivity of the anode. [13][14][15] Although significant achievements have been made on the LIBs performances with the use of nanostructured Si/C composite anodes, there are still various problems to be solved. The increased surface area of the nanostructured Si/C composite anodes results in a low initial coulombic efficiency.…”

“…In addition to this contribution, they reduce the mass transport losses in the structure by providing short diffusion distances for Li + ions 12 . On the other hand, carbonaceous materials such as graphite, graphene, and carbon nanotube act as matrix in the structure and they can buffer the volume change while they increase the conductivity of the anode 13‐15 …”