Binder-free self-supporting superflexible CNT-rGO/ Si@PC@SiO2 aerogel buckypaper as an anode for lithium-ion batteries and electrochemical properties

Constructing a self-supporting superflexible skeleton to protect silicon (Si) nanoparticles, to maintain capacity stability, and being suitable for the development of wearable electronics, which constitute the current technical bottleneck in the development of Si-based anode materials. In this paper, carbon nanotube-reduced graphene oxide/Si nanoparticles encapsulated by a double-layer film of porous carbon and SiO₂ (CNT-rGO/Si@PC@SiO₂) aerogel buckypaper (BP) was synthesized by directional pressure filtration and directional pressure infiltration. The Si nanoparticles were encased in a porous carbon shell and further encased by silica sol, preventing the occurrence of side reactions and the repeated formation of the solid electrolyte interphase (SEI). One-dimensional CNT and two-dimensional rGO jointly construct 3D superflexible porous conductive skeleton, eliminating the inert binder and collector. The silica sol bonded the cross-contact points to form a robust 3D skeleton, further improved the strength and flexibility, and also served as an active material to enhance battery capacity. Double-layer encapsulation and double-carbon superflexible porous skeleton preventing Si nanoparticles from falling off and suffering losses during charge-discharge cycles, so that high rate performance and long-cycle stability were obtained. The CNT-rGO/Si@PC@SiO₂ anode provides a stable capacity of 918.3 mAh/g after 200 cycles at 840 mA/g, and maintains a specific capacity of 675 mAh/g at 4200 mA/g. Its tensile strength was 1.47 MPa, without damage after folding into sharp creases or continuous 3000 cycles of 180° bending-straightening. The CNT-rGO/Si@PC@SiO₂ anode has great potential in wearable energy storage devices.