Rational Functionalization of Perylene Diimide for Stable Capacity and Long-term Cycling Performance for Li-ion Batteries

Perylene based dilithium salt of N,N'-bis (glycinyl) perylene diimide (Li₂-PDI) was synthesized and studied as an electrode material for lithium-ion batteries. The −CH₂−COOLi functionalization of perylene diimide is a simple strategy to mitigate the dissolution of the monomer in the electrolyte. The Li₂-PDI electrode exhibits excellent capacity retention behaviour and delivers a stable specific capacity of 101 mAh g⁻¹ after 100 cycles at a current density of 17 mA g⁻¹, which is 98% of theoretical specific capacity. A remarkably stable capacity of 87 mAh g⁻¹ was observed even after 1000 cycles with 100% coulombic efficiency at a current density of 200 mA g⁻¹. The reversible electrochemical lithiation/delithiation mechanism of Li₂-PDI was studied by ex-situ XRD and FT-IR spectroscopic techniques.