Constructing a high ion conductivity artificial SEI on biomass derived hard carbon for sodium ion battery

Abstract

Constructing an artificial SEI on a hard carbon surface effectively enhances initial coulombic efficiency (ICE) and cycling stability. A polymer electrolyte binder containing sodium ions (SPEB), consisting of PAAS and PEO, is designed using a straightforward method. A high ion conductivity artificial SEI is constructed on a pomelo peel-derived hard carbon (PHC) surface through esterification and hydrogen bonding. In hard carbon anodes for sodium ion batteries (SIBs), SPEB plays a crucial role by facilitating pre-sodiation in PHC, enhancing ion conductivity, and guiding the construction of a NaF-rich, ultra-thin, and stable SEI. The synthesized PHC possesses an outstanding reversible specific capacity of 375.13 mAh·g⁻¹, a superior ICE of 90.94 %, good rate capability, and excellent cycle stability. After 400 cycles at 0.9 A·g⁻¹, it retains 152.52 mAh·g⁻¹ with almost no decay. Meanwhile, SPEB demonstrates an exciting performance in other hard carbons and helps its commercialization application in SIBs.