High-performance of surface-treated Si-flakes anode via a Schiff-base reaction processed at room-temperature

Silicon (Si) is a promising anode material for high energy density lithium-ion batteries (LIBs). However, it is still a challenge to prepare high-performance Si material in a facile and cost-effective way. In this work, we designed a Schiff-base reaction processed in room temperature to modify the surface of recycled Si-flakes using lowcost pphthalaldehyde and 3,3 '-diaminobenzidine as the monomers and acetic acid as the catalyzer. The formed Schiffbase was well-coated on Si-flakes by forming hydrogen bonds. The resulted Si@Schiff-base exhibited largely enhanced initial coulombic efficiency compared to the bare one at 0.1C. Moreover, it achieved a high capacity of 1589 mAh g-1 at 420 mA g-1 and 975 mAh g-1 at 1000 mA g-1 after 200 cycles and 500 cycles, respectively, representing the outstanding cyclic performance. The greatly improved performance should be attributed to the suppressed volume expansion of Si anode and the reduced side-reactions on Si surface. It is worth noting that the Schiff-base polymer with conjugated structure and abundance of N and O atoms also simultaneouly enhanced the electron transfer and Li+ diffusion of the Si anode. Overall, our work pave the way for the practical application of Si anode in LIBs.