Two Birds with One Stone: Micro/Nanostructured SiO_x C_y Composites for Stable Li-Ion and Li Metal Anodes

Developing stable silicon-based and lithium metal anodes still faces many challenges. Designing new highly practical silicon-based anodes with low-volume expansion and high electrical conductivity, and inhibiting lithium dendrite growth are avenues for developing silicon-based and lithium metal anodes, respectively. In this study, SiO_x C_y microtubes are synthesized using a chemical vapor deposition method. As Li-ion battery anodes, the as-prepared SiO_x C_y not only combines the advantages of nanomaterials and the practical properties of micromaterials, but also exhibits high initial Coulombic efficiency (80.3%), low volume fluctuations (20.4%), and high cyclability (98% capacity retention after 1000 cycles). Furthermore, SiO_x C_y , as a lithium deposition substrate, can effectively promote the uniform deposition of metallic lithium. As a result, low nucleation overpotential (only 6.0 mV) and high Coulombic efficiency (≈98.9% after 650 cycles, 1.0 mA cm^-2 and 1.0 mAh cm^-2 ) are obtained on half cells, as well as small voltage hysteresis (only 9.5 mV, at 1.0 mA cm^-2 ) on symmetric cells based on SiO_x C_y . Full batteries based on both SiO_x C_y and SiO_x C_y @Li anodes demonstrate great practicality. This work provides a new perspective for the simultaneous development of practical SiO_x C_y and dendrite-free lithium metal anodes.