Rigid organic-inorganic coordination adaptable network integrated conformational transformation of BP based complex for superior potassium storage

Abstract

Black phosphorus (BP) is poised as a next-generation anode material for potassium-ion batteries (PIBs) due to its expansive interlayer spacing and superior conductivity. However, its limited cycling stability, particularly under high current densities, restricts its real-world utility. This research introduces a novel approach by encapsulating BP quantum dots (QDs) within S, N co-doped nanocages, anchored with Fe/Cu single atoms, and reinforced by an aminos-based covalent organic framework (FeCu-SNC@BP@COF) for enhanced K⁺ storage. The study observes a reversible transformation from hept-coordinated N₂PFe-CuN₃ to quadrilateral Cu-N₄ and Fe-N₃P units, facilitating rapid redox kinetics. Concurrently, the COF undergoes a structural shift from AA to ABC, disrupting long-range π-π stacking and short-range disorder, which significantly accelerates K⁺ transport and accommodates the substantial volume changes during cycling. As a result, FeCu-SNC@BP@COF achieves a high discharge capacity of 567 mAh g⁻¹ at a demanding rate of 20 A g⁻¹ and maintains an impressive 80.4 % capacity after 1000 cycles at 1 A g⁻¹. This atomic-scale coordination-environment integrated conformational transformation strategy (CEICT) offers profound insights into the development of self-adaptive, inherently fast-charging, and durable battery devices.