Is Soft Carbon a More Suitable Match for SiO_x in Li‐Ion Battery Anodes?

Abstract

Silicon oxide (SiOx), inheriting the high‐capacity characteristic of silicon‐based materials but possessing superior cycling stability, is a promising anode material for next‐generation Li‐ion batteries. SiOx is typically applied in combination with graphite (Gr), but the limited cycling durability of the SiOx/Gr composites curtails large‐scale applications. In this work, this limited durability is demonstrated in part related to the presence of a bidirectional diffusion at the SiOx/Gr interface, which is driven by their intrinsic working potential differences and the concentration gradients. When Li on the Li‐rich surface of SiOx is captured by Gr, the SiOx surface shrinks, hindering further lithiation. The use of soft carbon (SC) instead of Gr can prevent such instability is further demonstrated. The higher working potential of SC avoids bidirectional diffusion and surface compression thus allowing further lithiation. In this scenario, the evolution of the Li concentration gradient in SiOx conforms to its spontaneous lithiation process, benefiting the electrochemical performance. These results highlight the focus on the working potential of carbon as a strategy for rational optimization of SiOx/C composites toward improved battery performance.

Flexible Electronic Systems via Electrohydrodynamic Jet Printing: A MnSe@rGO Cathode for Aqueous Zinc-Ion Batteries

“…Meanwhile, the lattice spacing coincides with that of graphite, indicating a significant reduction degree of rGO. The Raman spectra of MnSe@rGO-1, MnSe@rGO-3, and MnSe@rGO-5 (Figures c and S2c) exhibit the characteristic D (1347 cm –1 ) and G (1581 cm –1 ) bands of rGO, where the D band is assigned to the first-order scattering of E 2g phonons and the G band to the breathing mode of κ-point phonons of A 1g symmetry. − Interestingly, MnSe@rGO-1, MnSe@rGO-3, and MnSe@rGO-5 exhibit similar I D /I G ratios of 0.93, 0.91, and 0.91, respectively (Figure S2d), probably because of the excessive amount of Se impurity produced during the preparation process. The Se doping amounts in the rGO of the materials are close, thus affording similar I D /I G values.…”

Relaxation Analysis of Silicon Monoxide-Graphite Composite Anode

“…A•1 in the appendix, the lithium-ions were inserted into SiO at 0.7 V in the beginning of charging as the previous reports. 23,48 On the other hand, the potential was reduced as low as that of graphite at the end of charging, 26,49 indicating that lithium-ions were inserted into graphite as well as SiO. 27 The surface of SiO might accept excess amount of lithium at the termination of the lithium insertion, and lithium migration from the surface of SiO into core should occur during the relaxation.…”

“…20 Since the charging potential of SiO is higher than that of graphite, SiO 16,21,22 is primarily lithiated in the composites at the beginning of charging as the case of the Si-graphite system. [23][24][25] However excess amounts of lithium-ions are thought to be introduced into graphite after charging to some content 21,26 due to the slow reaction of SiO in comparison with the intercalation of Li-GIC. 27 At the end of charging, the lithium distributions of SiO and graphite are thought to be different from the equilibrium ones.…”

A Layered Bi2Te3@PPy Cathode for Aqueous Zinc‐Ion Batteries: Mechanism and Application in Printed Flexible Batteries

“…The growing demand for renewable energy sources has created an urgent need for reliable and safe energy storage solutions. [1][2][3][4][5][6] water molecules in aqueous solutions, resulting in larger hydrated ions with an approximated size of 5.5 Å. [24] These relatively large Zn-based ions further challenge the Zn 2+ insertion/extraction, which eventually causes a rapid capacity degradation during long-term cycling.…”

“…The growing demand for renewable energy sources has created an urgent need for reliable and safe energy storage solutions. [ 1–6 ] Rechargeable aqueous zinc‐ion batteries (ZIBs) possess numerous advantages, including the high theoretical capacity of the zinc metal anode (5851 mAh mL −1 in volume and 820 mAh g −1 in mass), the abundance of zinc in the earth's crust (79 ppm), the small ionic radius of Zn 2+ (0.74 Å), the use of non‐toxic aqueous electrolyte, the possibility of fabrication in air, and excellent stability and reversibility. [ 7–12 ] These key traits make ZIBs highly promising as energy storage systems, especially for applications where cost and safety are major concerns, from large systems for the integration of renewables to small designs for wearable electronics.…”