Graphitic carbon nitride (g-C3N4) as an electrolyte additive boosts fast-charging and stable cycling of graphite anodes for Li-ion batteries

Abstract

Graphite is the most popular anode material in lithium ion batteries (LIBs), however, it suffers from the poor reaction kinetics and degraded structure stability during long-term cycling. Surface modification of the graphite electrode and advanced electrolyte design were used to address the challenge. Yet, the previous efforts either involved multi-step reaction process or brought in discontented performance. In this work, we introduce a facile method to improve the rate and cycle performance of graphite, by adding graphitic carbon nitride (g-C3N4) to the electrolyte. The additive not only induces anions to participate in the solvation structure with lower desolvation energy, but also participates in the SEI formation, which contains Li3N and more LiF at the graphite interface. Consequently, the structural integrity and reaction kinetics of graphite during cycling are enhanced. The assembled graphite||Li cell with modified electrolyte exhibits excellent cycle and rate performance, a reversible specific capacity of 209 mAh g-1 is achieved over 600 cycles at a high current density of 2000 mA g-1, which is far superior to that in pristine electrolyte and outperforms other modified graphite electrode in literature. Furthermore, the modified electrolyte endows the graphite electrode superior cycle stability even at 60 ℃, with a remarkable capacity of 360 mAh g-1 after 100 cycles at 100 mA g-1. This study provides a facile strategy to design electrolyte for graphite based lithium ion batteries with fast charge-discharge behavior and long cycle stability.