Extensively cross-linked conductive dual carbon substrate network for high-performance silicon anode

Abstract

Silicon (Si) anodes, with high theoretical capacity, hold great promise for applications in lithium-ion batteries (LIBs). However, it confronts the challenges because of significant volume expansion (∼300 %) and poor electrical conductivity. In this study, we developed a Si based anode material by encapsulating Si nanoparticles within a dual-carbon substrate network to realize the high conductivity and buffering structure for Si. The inner carbon layer is derived from phenolic resin (RF), and possesses rich mesopores that provides buffer space to mitigate the expansion of Si, thereby maintaining the mechanical integrity of anode. Furthermore, the nitrogen-doped carbon (NC) of outer layer derived from conductive polyaniline exhibits high conductivity (1.824 × 10 S·m⁻¹) and highly cross-linked structure, which effectively shortens the Li⁺ transport path, reducing the energy barrier for Li⁺ transmission to the Si core. Due to the synergistic protective effect of the inner porous structure and the outer highly cross-linked conductive network, the prepared material (named as Si@RF@NC) shows suppressed volume changes and enhanced electron and ion transport, thus maintaining electrode structural integrity and forming a stable solid electrolyte interphase film. After 100 cycles, the Si@RF@NC anode exhibits a high specific capacity of 762.4 mAh g⁻¹, with a capacity retention rate of 72.8 %, and an electrode expansion rate post-cycling of only 15.56 %. This study provides insights into the design of high-energy LIBs with suppressed expansion in Si anodes.