Yolk shell structured YS-Si@N-doped carbon derived from covalent organic frameworks for enhanced lithium storage.

[Display omitted] • N-doped carbon-coated Si nanocomposites with yolk shell structure (YS-Si@NC-60) derived from covalent organic frameworks (COFs) were prepared by template-free method. • Through an interesting Ostwald ripening, the core–shell Si@COP TBBA is transformed into the yolk-shell Si@COF TBBA. • The well-ordered pore structure of the COFs derived N-doped carbon shell can shorten the transport path of Li+. • The YS-Si@NC-60 with yolk shell structure can not only ease the volume expansion of silicon, but also has high ICE and cycle stability. Silicon (Si) has ultra-high theoretical capacity (4200 mAh g−1) and accordingly is widely studied as anode materials for lithium-ion batteries (LIBs). However, its huge volume expansion during charging/discharging is a fatal challenge. The preparation of Si-based composite materials with yolk shell structure is the key to solving the Si volume expansion. Here, N-doped carbon-coated Si nanoparticles (SiNPs) nanocomposites (YS-Si@NC-60) with yolk shell structure derived from covalent organic frameworks (COFs) was prepared. N-doped carbon shells derived from COFs not only maintain the well-ordered nanosized pores of COFs, which facilitates the transport of Li+ to contact with internal SiNPs, but also provide more extra active sites for Li+ storage. Most importantly, the internal void can effectively alleviate the damage effect of SiNPs volume expansion. The obtained YS-Si@NC-60 as a LIBs anode show high cyclic stability and Li+ storage performances. At 0.1 A g−1, the capacity is 1446 mAh g−1 after 110 cycles, and initial coulomb efficiency is as high as 82.2 %. The excellent performance can be attributed to the unique yolk shell structure. This simple and template-free strategy provides a new idea for preparing Si-C nanocomposites with yolk shell structure. [ABSTRACT FROM AUTHOR]