Hollow SiO_x/C Microspheres with Semigraphitic Carbon Coating as the “Lithium Host” for Dendrite-Free Lithium Metal Anodes

Metallic lithium is an attractive high-energy-density anode for lithium batteries. However, its practical application is puzzled by dead lithium generation, dendrite formation, and poor Coulombic efficiency, which leads to a short cycle life. Three-dimensional hosts can be applied to control the growth of Li . Herein, a SiOx/C@SGC Li host material consisting of a hollow central cavity, a lithiophilic SiOx/C composite inner shell, and a highly conductive semi-graphitic carbon (SGC) outer shell has been designed through hard templating and chemical vapor deposition. When applied as the Li host, the lithiophilic SiOx/C inner shell regulates Li growth, while the SGC coating shell guarantees high conductivity and structural integrity. The obtained SiOx/C@SGC exhibits an excellent Coulombic efficiency of 99% at 1 mA cm–2 after 350 cycles, and the symmetric cell shows a low voltage hysteresis of 15 mV without notable fluctuation for over 1200 h. Ex situ transmission electron microscopy and in situ optical microscopy characterizations demonstrate the successful deposition of Li into the hollow cavity of SiOx/C@SGC. This contribution provides insights into the reasonable design of dendrite-free Li metal anodes.