Controllable Preparation of Hierarchically Charge-Separated Interface to Effectively Promote the Desolvation and Kinetics of Lithium Ions.

Abstract

Solid-electrolyte interphase (SEI) is one of the key factors to determine the performance of batteries. Electrolyte additives enhance SEI performance for fast charging and long cycle life but introduce system-level uncertainties, including cathode degradation, safety hazards, and cost escalation. In this study, we prepare a composite electrode (BPQDs/GDYNTs) featuring a charge-separated interface structure to improve the SEI directly without auxiliary additives. The BPQDs/GDYNTs are comprised of graphdiyne tubes (GDYNTs) with black phosphorus quantum dots (BPQDs) distributed on the surface. The charge transfer between BPQDs and GDYNTs creates a charge-separated interface, thereby enabling the efficient adsorption of lithium (Li) ions by the electron-rich state of GDYNTs while promoting the adsorption of hexafluorophosphate anion (PF6 -) on the electron-deficient state of BPQDs. That facilitates the in situ formation of a thin and inorganic-rich SEI containing fluorine- and phosphorus-based species, which significantly enhances both the desolvation of Li-ions and their kinetics. When utilized as the anode of Li-ion batteries, the BPQDs/GDYNTs electrode exhibits fast-charging capability and remarkable longevity, demonstrating ultra-stable cycling performance over 50 000 cycles at a high current density of 10 A g-1 with negligible capacity decay.