Vertical Graphene Growth on SiO Microparticles for Stable Lithium Ion Battery Anodes

Abstract

Silicon-based materials are considered as strong candidates to next-generation lithium ion battery anodes because of their ultrahigh specific capacities. However, the pulverization and delamination of electrochemical active materials originated from the huge volume expansion (>300%) of silicon during the lithiation process results in rapid capacity fade, especially in high mass loading electrodes. Here we demonstrate that direct chemical vapor deposition (CVD) growth of vertical graphene nanosheets on commercial SiO microparticles can provide a stable conducting network via interconnected vertical graphene encapsulation during lithiation, thus remarkably improving the cycling stability in high mass loading SiO anodes. The vertical graphene encapsulated SiO (d-SiO@vG) anode exhibits a high capacity of 1600 mA h/g and a retention up to 93% after 100 cycles at a high areal mass loading of 1.5 mg/cm. Furthermore, 5 wt % d-SiO@vG as additives increased the energy density of traditional graphite/NCA 18650 cell by ∼15%. We believe that the results strongly imply the important role of CVD-grown vertical graphene encapsulation in promoting the commercial application of silicon-based anodes.

Pressure‐Induced Vapor Synthesis of Carbon‐Encapsulated SiOx/C Composite Spheres with Optimized Composition for Long‐Life, High‐Rate, and High‐Areal‐Capacity Lithium‐Ion Battery Anodes

“…Depending on the used precursors, the Si 2p3/2 , O 1s , and C 1s peaks are located in the range of 103.51–102.02, 532.91–532.37, and 284.78–284.16 eV, respectively. According to previous reports, the Si 2p3/2 peak locates at about 99 and 104 eV for elemental Si and SiO 2 , respectively, suggesting that the aforementioned five SiO x /C samples contain suboxidized Si (SiO x , x < 2) . The O 1s peaks ranging from 532.91 to 532.37 eV may arise from the overlapping of Si—O—Si, C—O—Si, and C—O—C peaks .…”

“…Because of the higher Si/O ratio for HMD (1:0) than that of HMDS (1:0.5), the product derived from HMD contains higher SiC content than that from HMDS, resulting in the higher XRD peak intensity of SiC for the product from HMD. With respect to the Raman spectra, two peaks located at ≈1332 and ≈1602 cm −1 were observed for all the samples (Figure b), being the D and G peaks characteristic of carbon materials, respectively . This indicates that all the SiO x /C samples contain elemental carbon.…”

“…Therefore, searching for new anode materials is of great significance for developing advanced LIBs. Many materials have been investigated to act as the next‐generation anodes due to their high Li‐ion storage capacity, e.g., silicon, silicon suboxide (SiO x , x < 2), metal (Sn, Mg, etc. )/metal alloys, metal oxides (SnO x , TiO 2 , etc.…”

“…For these candidate materials, SiO x is attractive because it exhibits better stability than pure Si. Still, the SiO x materials experience huge volume expansion/contraction during the lithiation and delithiation processes, which causes breaking of the SiO x materials and rapid decay of the performance . Especially at a high mass loading, the capacity decreases more quickly because the electrode structure and electrical connectivity are easier to be destructed .…”

Preparation of Flexible Self‐Supporting 3D SiOx‐Based Membrane Anodes with Stabilized Electrochemical Performances for Lithium‐Ion Batteries

“…Miyachi et al demonstrated that the irreversible products of Li 2 O and Li 4 SiO 4 formed in the first cycle act as a buffer layer to alleviate the effect of volumetric change and prevent the inner SiO x from further contacting with the electrolyte to increase the coulombic efficiency (CE) . Shi et al reported that when graphene grows vertically on the SiO x surface through a chemical vapor deposition (CVD), a capacity of 1600 mAh g −1 can be obtained …”