Carbon black SP is a carbon material more suitable for SiOx than graphite

Abstract

To enhance the cycle stability of the SiOx anode in high-energy-density lithium-ion batteries from the perspective of electrode formulation, this paper investigates why SP is more suitable for SiOx than Gr, as well as the influence of SP content on the performance of the SiOx anode. The findings reveal that, compared to Gr, SP exhibits superior ionic conductivity. Moreover, the carbon binder domains (CBD) network formed by SP and the binder demonstrates a more effective buffering capacity against the volume expansion of SiOx than that of Gr. Additionally, SP is observed to elevate the lithium intercalation potential of SiOx, thereby endowing SiOx with a higher specific capacity. Nonetheless, the use of SP also introduces several challenges. On one hand, it can induce uneven lithium deposition on the composite electrode, leading to electrode cracking. On the other hand, the very low initial coulombic efficiency (ICE) of SP results in an irreversible loss of lithium ions on the cathode electrode side in a full cell configuration. Consequently, when designing a full cell, it is imperative to consider the inherent characteristics of SP, and optimization can be achieved by adjusting the negative/positive capacity ratio (N/P) or employing prelithiation methods.