Electrochemical behavior and self-organization of porous Sn nanocrystals@ acetylene black microspheres in lithium-ion half cells

摘要

We report a facile route to synthesize porous Sn nanocrystals@acetylene black microspheres (Sn@AB MSs) via a galvanic replacement reaction of Zn microspheres in a SnCl2 solution consisting of acetylene black (AB). The half cells of lithium-ion batteries with the Sn@AB MSs as the working electrode have a charge capacity of 480.8 mA h g(-1) at 100 mA g(-1) after 100 cycles, and the charge capacity of the half cells after the 100th cycle is slightly larger than that after the 80th cycle. The SEM images reveal that the electrode layer from the Sn@AB MSs experiences surface cracking during electrochemical cycling, while prolonged cycling leads to the closure of cracks. Electrochemical cycling induces self-organization of Sn and AB to form rose-like porous Sn@AB/Li2SnO3 microflowers from porous Sn@AB MSs. The closure of cracks and formation of porous Sn@AB/Li2SnO3 microflowers likely cause the increase of the charge capacity. The experimental results demonstrate that the porous Sn@AB MSs with acetylene black around Sn can alleviate the large volumetric strain due to lithiation/delithiation, reduce the migration distance of lithium to active sites, and promote exceptional Li storage, leading to better cycling stability.