PVP-grafted synthesis for uniform electrospinning silica@carbon nanofibers as flexible free-standing anode for Li-ion batteries

Abstract The application of the SiO2 anodes for flexible and free-standing lithium-ion batteries (LIBs) is restricted by the weaknesses of SiO2 nanoparticles, such as agglomeration, huge volume expansion and rapid capacity fading during charge/discharge cycles. Herein, the PVP-grafted-silica@carbon nanofibers (PVP-g-SiO2@CNF) flexible free-standing anode with high capacity and long cycle stability is successfully fabricated by PVP-grafted-SiO2, electrospinning and subsequent heat treatment. PVP modifies the interface between SiO2 nanoparticles and electrospinning solution to prevent the nanoparticles from aggregation, which makes them are uniformly encapsulated in nanofibers. The uniform structure is beneficial to enhance the interface contact between SiO2 and Li+, and alleviate volume expansion during lithiation. Furthermore, PVP introduces mesoporous into carbon nanofibers, facilitating the transports of ions and electrons to attain high-rate performance. As a flexible free-standing anode material for LIBs, PVP-g-SiO2@CNF achieves high reversible capacity, high-rate capacity and superior cycle stability (440 mAh g−1 at 0.1 A g−1 after 200 cycles), especially 89% capacity retention after 180° bending deformation. Consequently, enhanced capacity and cycle stability for flexible free-standing anode are available through PVP-grafted interface modification and electrospinning.