In-situ pre-lithiated onion-like SiOC/C anode materials based on metallasilsesquioxanes for Li-ion batteries

Abstract

SiOC/C demonstrates attractive potential as anode materials for high-energy-density lithium ion batteries (LIBs) due to the high capacity and cycling stability. However, the excessive consumption of Li ions during the initial cycles is still a great challenge for practical application in LIBs. Herein, we fabricate onion-like SiOC/C spheres with high initial coulombic efficiency using the in-situ chemical pre-lithiation strategy by one-step injection pyrolysis of lithium hepta(i-butyl) silsesquioxane trisilanolate. The LixSiOy could be uniformly generated inside the onion-like SiOC/C spheres during pyrolysis, which effectively reduces the irreversible consumption of Li ions and avoids the complicated pre-lithiation process. Notably, when applied as anode for LIBs, as-prepared SiOC/C spheres exhibit a high initial coulombic efficiency of ca. 80 % and good cycling stability after 500 cycles. Additionally, the onion-like structure and homogeneous distribution of pre-generation of LixSiOy endow SiOC/C spheres superior structural integrity. Furthermore, the cell using LiCoO2 and SiOC/C spheres as cathode and anode, respectively, performs high energy density and satisfactory cycling stability, which indicates the broad prospect in application in LIBs of the in-situ chemical pre-lithiation strategy.