Significantly enhanced performance of Li-storage via in-situ oxidation of silicon particles by zinc oxide

Facile synthesis of multi-phase (Si+SiO2)@C anode materials for lithium-ion batteries

“…41 In the reverse scan, two anodic peaks appeared at 0.35 and 0.5 V, corresponding to various Li X Si dealloying and accompanying amorphous Si formation, and a weak oxidation peak appeared at around 1.0 V, which probably corresponds to the de-lithiation reaction of a small amount of reactive SiO 2 in the interior. 38,41,42 As the number of scanning cycles increases, the electrode is continuously activated and the intensity of the oxidation and reduction peaks gradually increases and the peaks broaden. This is mainly originated from the disruption of the crystal structure and amorphous transformation during the discharge–charge process, leading to additional silicon phase activation.…”

“…After milling, low-cost kerosene (GR, Sigma-Aldrich) was used as a carbon source for carbon coating by vapor phase deposition at 900 °C for 1 h. For details on how carbonization works, refer to the Experimental section of our previously published work. 38 The SS50 carbon coating is marked as (Si+SiO 2 )@C, which is denoted as SS50-900C. The material synthesis process is illustrated with the schematic diagram of the sample preparation, as shown in Fig.…”

“…Compared with Si, the Si 2p curve of the ball-milled sample SS50 after the introduction of silica can be deconvoluted into six sub-curves, ranging from high to low binding energies corresponding to different valence states of Si. [38][39][40] It can be seen that the significant change in the valence state is shifted from the low binding energy to the high binding energy position, which implies that the silicon surface is shifted from a low to a high valence state. This is mainly because the crushed micron silicon exposes the fresh surface with abundant dangling bonds interacting with the silica surface, and certain physicochemical bond interaction occurs on the silicon surface, which causes the peaks of the intermediate oxidation state to become stronger and broader.…”

Dual-Phase SiC + C Coated Microsize Si@SiOx Powder as Anode Material for Li-Ion Batteries

“…EIS, GITT, and CV tests with different scan rates were tested for WM-30C to facilitate the description of its reaction kinetic mechanism. As displayed in Figure a, for the EIS tested before cycling, the low-frequency region corresponds to the lithium-ion (Li + ) diffusion process, and the semicircle in the high-frequency region corresponds to the charge transfer resistance ( R ct ) of the electrode . The smaller R ct of the WM-30C may be attributed to the introduction of the carbon material as well as the change of the internal Si–O valence state in favor of the electronic conductivity.…”

“…As displayed in Figure 5a, for the EIS tested before cycling, the low-frequency region corresponds to the lithium-ion (Li + ) diffusion process, and the semicircle in the high-frequency region corresponds to the charge transfer resistance (R ct ) of the electrode. 45 The smaller R ct of the WM-30C may be attributed to the introduction of the carbon material as well as the change of the internal Si−O valence state in favor of the electronic conductivity. The relationship between impedance and ω −0.5 in the low-frequency region is shown in Figure 5b, where the WM-30C electrode has a lower slope, suggesting that the electrode has a lower Warburg impedance and therefore a higher lithium ion diffusion (D Li+ ) coefficient, where the D Li+ coefficient can be determined from the Warburg coefficient in the Supporting Information (eq S1), and the results of the EIS tests suggest that the incorporation of the introduced carbon source precursor and the subsequent heat treatment process produced (Si + SiO x + SiC + C) multiphase composites, which reduced the impedance of the WM-30C electrode, accelerated the migration of lithium ions inside the electrode structure, quickened the reaction kinetics, and improved the electrochemical performance of the electrode.…”