Optimal Structural Design to Improve Cycling Stability of SiO x -Spherical Porous CNTs Composite Anode for Lithium-Ion Battery

Silicon suboxide (SiOx) has emerged as a viable anode material for lithium-ion batteries (LIBs) because of its high theoretical specific capacity and structural stability. However, its practical application is restricted by inadequate cycling stability and poor electrical conductivity. Herein, plasma-enhanced chemical vapor deposition (PE-CVD) was utilized to synthesize SiOx-SPC composites, in which the optimized spherical porous CNTs (SPC) provided a well-defined porous framework that facilitated uniform SiOx deposition. The resulting SiOx-SPC composite (SSC) exhibits high electrical conductivity, Li-ion diffusivity, and mechanical stability, which remarkably enhance the cyclic stability and rate capability. As a result, the SSC electrode exhibits a high initial specific capacity of 1032.26 mAh g⁻¹ and achieves exceptional cycling performance, considerably surpassing microsized SiOx (MSiOx) particles (∼102% vs ∼41% retention after 100 cycles at 0.5C). Moreover, SSC shows enhanced Li-ion diffusion (4.66 × 10⁻¹⁰ cm² s⁻¹) as evaluated by cyclic voltammetry. This work demonstrates the essential role of the SiOx coating on optimized SPC via PE-CVD and enables the development of long-lasting, high-capacity anode materials for advanced lithium-ion battery technologies.