Pre-lithiated silicon/carbon nanosphere anode with enhanced cycling ability and coulombic efficiency for lithium-ion batteries

Abstract

The high capacity and low charge potential of Si-based materials have attracted significant attention in recent years, positioning them as promising candidates for lithium-ion batteries (LIBs). However, these materials face challenges such as insufficient conductivity and substantial volumetric expansion. To address these concerns, two strategies have been employed: constructing a carbon coating layer and implementing pre-lithiation. Si nanospheres are dispersed in a precursor solution and subsequently annealed to undergo carbonization, resulting in the formation of Si/C composites. The Si/C anode has been pre-lithiated using a simple electrochemical pre-lithiation method to enhance the initial coulombic efficiency. Specifically, it achieved a reversible capacity of 1018.4 mAh g−1 after 500 cycles at a current density of 0.5 A g−1 for LIBs. Even at a high current density of 5 A g−1, the capacity remained stable at 266.4 mAh g−1 after 500 cycles. Moreover, pre-lithiation significantly improved the coulombic efficiency in the first cycle, increasing it from 64.89 % to 96.18 %. The enhanced performance can be attributed to the carbon coating layer, which improves material conductivity and mitigates volume expansion. Our work demonstrates that the prepared Si/C anode exhibits excellent long-term cycling performance and a high-rate capability. These findings provide valuable insights for developing high-performance LIBs by leveraging the specific structure of Si-based materials.