Carbon Shells and Carbon Nanotubes Jointly Modified SiO_<i>x</i> Anodes for Superior Lithium Storage

Micron-sized silicon oxide (SiOx) is a preferred solution for the new generation lithium-ion battery anode materials owing to the advantages in energy density and preparation cost. Nonetheless, its limited conductivity coupled with significant volume expansion results in structural instability and a swift decline in capacity. Herein, low-pressure chemical vapor deposition (LPCVD) and spray drying were employed to construct a composite anode material with a dual conductive carbon coating encapsulating silicon oxide (SiOx@C@CNTs). LPCVD-derived carbon coatings can substantially reduce the volumetric variations in SiOx, leading to the formation of a stable solid electrolyte interphase layer on its surface. Then, the carbon nanotube (CNT) conductive network can provide a fast transmission channel for charge exchange. Consequently, the SiOx@C@CNTs anodes have excellent cycling stability (624.7 mAh g–1 after 1000 cycles at 2 A g–1) and rate performance (790.3 mAh g–1 reversible lithium storage capacity at 4 A g–1). When paired with NCM811 cathode materials in full cells (SiOx@C@CNTs/G∥NCM811), these anodes provide a substantial energy density of 401.8 Wh kg–1 coupled with a stable cycling performance, achieving 134.8 mAh g–1 after 100 cycles at a rate of 1 C, with a capacity retention rate of 80.7%.