CNTs-Functionalized Porous Hard Carbon Matrix: Si Deposition Optimization and Lithium-Ion Battery Performance Enhancement

The silicon/carbon (Si/C) material is greatly expected to be the most potential anode for advanced lithium-ion batteries (LIBs). Incorporating nanoscale Si with a suitable carbon matrix is desirable but remains challenging. Here, carbon nanotubes (CNTs) modified porous hard carbon (PCCN) is designed to carry Si nanoparticles (Si NPs), encapsulated with the outermost carbon layer to form the PCCN@SC material. DFT calculations reveal that the ordered lattice structure of CNTs facilitates the uniform deposition of Si NPs, suppressing the continuous growth of the particles and mitigating volume expansion ratios. The mechanical rigidity of PCCN is enhanced through CNT incorporation, effectively mitigating stress accumulation during lithiation and ensuring structural stability under cycling strain, which has been confirmed by theoretical simulations. Besides, the uniform pore distribution accelerates the transport of electrons and Li ions, thereby improving reaction kinetics through optimized ion diffusion pathways. As a result, the prepared PCCN@SC anode exhibits excellent electrochemical performance, and the PCCN@SC||NCM811 full cell depicts a capacity retention of 86.9% after 110 cycles and achieves an ultrahigh rate of 8 C.