N-rich porous Si@SiOx/NC composites derived from in situ polymerisation of acrylic acid as anode for Li-ion batteries

Si possesses a high theoretical specific capacity as anode material for Li-ion batteries. However, it has poor electrical conductivity and severe volume effect during charge-discharge processes, resulting in substantial internal resistance and significantly reduced available capacity. These issues can be greatly mitigated by encapsulating Si nanoparticles within a carbonous material. Hence, network precursors are synthesised herein to encapsulate Si nanoparticles by in situ polymerisation of acrylic acid and melamine. After freezedrying, the precursors are pyrolysed under Ar atmosphere to obtain homogeneous N-rich porous Si@SiOx/ NC composites. A fibrous network structure is acquired by using appropriate amounts of polyacrylic acid and Si. Such a structure provides an outstanding electron transmission network and effectively buffers the volume change of Si to maintain a stable electrode structure. The results show that when the content of Si nanoparticles in the composite is 35.2 wt%, the prepared Si@SiOx/NC-2 composite has abundant micropores (267.90 m2 g-1) and mesopores (17.48 m2 g-1). The material shows an initial discharge-specific capacity of 1833.6 mAh g-1 and Coulombic efficiency of 65%. After 150 cycles at 0.1 A g-1, the discharge-specific capacity is still as high as 922.8 mAh g-1. The excellent electrochemical performance of the Si@SiOx/NC composites is due to the three-dimensional conductive structure. The unique construction could play an important role in expanding the commercial application of Si-based anode materials in Li-ion batteries. (c) 2023 Elsevier B.V. All rights reserved.