Ternary Si–SiO–Al Composite Films as High-Performance Anodes for Lithium-Ion Batteries

Abstract

Silicon (Si) is a promising anode material for lithium-ion batteries but has long been suffering from low conductivity, drastic volume change, poor cycling performance, etc. Adding SiO, Al, etc. to form Si-based binary composite films can improve some properties but have to give up others. Here, we prepared a ternary Si–SiO–Al composite film anode by adding SiO and Al together into Si using magnetron sputtering. This film has an extraordinary combination of conductivity, specific capacity, cycling stability, rate performance, etc., when compared with its binary and unary counterparts. While both SiO and Al can separately mitigate anode cracking resulting from the huge volume expansion during the lithiation/delithiation cycling process, the synergetic effect of adding SiO and Al together to form a ternary composite film can produce much better results. This film maintains an island structure that can efficiently buffer the volume expansion during the cycling process, giving rise to superior cycling performance and excellent rate performance. In addition, the cosputtered Al improves the electrical conductivity of the anode at the same time. This unique combination of anode properties, together with the low cost, suggests that the Si–SiO–Al composite film has the potential to be commercialized as a binder-free anode for lithium-ion batteries. This work also provides an efficient means to modulate the anode properties with more degrees of freedom.

Combining Surface Holistic Ge Coating and Subsurface Mg Doping to Enhance the Electrochemical Performance of LiNi0.8Co0.1Mn0.1O2 Cathodes

“…However, the NCM811-Mg@Ge electrode always contributes more capacitive percentage than NCM811 and NCM811-Mg at any specific scanning rate, indicating that the enhancement of the rate performance of NCM811-Mg@Ge comes from the improved capacitive effect. Similar observations can be found in previous reports …”

“…However, the redox peaks of NCM811-Mg@Ge have better symmetry (Figure c), indicating that the NCM811-Mg@Ge electrode has faster Li-ion diffusion and transmission. To determine whether pseudocapacitance behavior exists during the charging/discharging process, b values are calculated according to the equation in the literature, , and the result is displayed in Figure g. Figure g shows that the b values of NCM811, NCM811-Mg, and NCM811-Mg@Ge are 0.65, 0.69, and 0.75, respectively, illustrating that the charge storage comes from the surface capacitive effect and diffusion-controlled insertion process.…”

Improving Electrochemical Performance of Thick Silicon Film Anodes with Implanted Solid Lithium Source Electrolyte

“…The anode capacity consists of capacitive and diffusive contributions, both of which can be approximately identified from CV curves. 49 As illustrated in Figure 3c, for Si-SE film, the b-value is 0.71 for the cathodic peak and 0.82 for the anodic peak, respectively, suggesting the charge storage capacity is dominated by both surface capacitive and diffusion-controlled interfacial reaction. On the contrary, for Si film (Figure 3c), the b-value is near 0.5 (0.57 for the cathodic peak and 0.48 for anodic peak), demonstrating that the diffusive effects predominate in the charge storage mechanism.…”

“…In addition, the redox peaks of Si-SE film have better symmetry at a high scan rate, compared to that of Si film, suggesting that Li ions have a higher diffusion/transmission rate in the Si-SE film. The anode capacity consists of capacitive and diffusive contributions, both of which can be approximately identified from CV curves . As illustrated in Figure c, for Si-SE film, the b -value is 0.71 for the cathodic peak and 0.82 for the anodic peak, respectively, suggesting the charge storage capacity is dominated by both surface capacitive and diffusion-controlled interfacial reaction.…”

Scalable Layer-by-Layer Stacking of the Silicon-Graphite Composite: Prelithiation Strategy of the High-Capacity Anode for Energy/Power-Dense Li Batteries

“…To meet the increasing practical demands for electric vehicles and portable electronics, the development of advanced lithium-ion batteries (LIBs) with high power and energy density has stimulated the reform of electroactive materials. − Silicon (Si) is identified as the most prospective anode candidate due to its high specific capacity (Li 15 Si 4 ), low discharge potential (<0.35 V), and natural earth-crust abundance. − Unfortunately, several key issues hinder the commercial application of the high-capacity Si anode. The huge volume variation (∼300%) during the lithiation/delithiation process of the silicon anodes incurs repetitive buildup of the solid electrolyte interphase (SEI) due to the exposure of the active intermediate species in the aprotic electrolyte, leading to the electrode pulverization, reduced Coulombic efficiency, as well as enhanced interfacial resistance. ,− Another inherent disadvantage of Si anodes is their inferior conductivity, which exacerbates the cell polarization and limits the power-oriented applications. ,, …”