Well-dispersed Sb particles embedded on N-doped carbon nanofibers toward high-performance Li-ion battery

The alloy-type material Sb is widely used in the anode materials of lithium-ion batteries (LIBs) due to its high theoretical specific capacity. However, its serious volume expansion problem during alloying/dealloying of Li+ limits its practical application. In this work, C-Sb composite was constructed as anode material of LIBs by electrospinning route for the first time, Sb was introduced into the polyacrylonitrile-based hard carbon and coal tar pitch-based soft carbon composite amorphous carbon fiber with a diameter of 300–600 nm, which realized high cycling stability. The C-Sb-2 (the mass ratio of polyacrylonitrile to Sb source is 1:2) electrode displayed charge capacities of 1098.5, 930.3, 841.7, 753.5, 643.9 and 545.8 mAh·g−1 at 0.1, 0.2, 0.3, 0.5, 1 and 2 A·g−1, respectively. And when the current density returned to 0.1 A·g−1, the charge capacity was 939.3 mAh·g−1, revealing good stability and reversibility. The introduction of Sb into the amorphous carbon improved its conductivity and addressed the volume expansion issue of high specific capacity Sb during charge/discharge. Ex-situ XRD analysis confirmed the high reversibility of the C-Sb-2 during charging and discharging. Density functional theory (DFT) calculations revealed the gradual enhancement of the interface interaction between SbxLiy and amorphous carbon (AMC) with increasing lithium content, contributing to the anchoring of alloy nanoparticles on the AMC surface and buffering the volume change of the alloy. Moreover, the gradual lithiation of Sb facilitated the electron transfer from SbxLiy to AMC. These findings hold promise for designing lithium storage materials with exceptional performance, highlighting the potential of C-Sb composites as anode materials for efficient next-generation lithium storage.