A Yolk–Shell Structured Silicon Anode with Superior Conductivity and High Tap Density for Full Lithium‐Ion Batteries

Abstract The poor cycling stability resulting from the large volume expansion caused by lithiation is a critical issue for Si‐based anodes. Herein, we report for the first time of a new yolk–shell structured high tap density composite made of a carbon‐coated rigid SiO 2 outer shell to confine multiple Si NPs (yolks) and carbon nanotubes (CNTs) with embedded Fe 2 O 3 nanoparticles (NPs). The high tap density achieved and superior conductivity can be attributed to the efficiently utilised inner void containing multiple Si yolks, Fe 2 O 3 NPs, and CNTs Li + storage materials, and the bridged spaces between the inner Si yolks and outer shell through a conductive CNTs “highway”. Half cells can achieve a high area capacity of 3.6 mAh cm −2 and 95 % reversible capacity retention after 450 cycles. The full cell constructed using a Li‐rich Li 2 V 2 O 5 cathode can achieve a high reversible capacity of 260 mAh g −1 after 300 cycles.