Tailoring Self-Catalytic N─Co Bonds into Heterostructure Architectures: Deciphering Polytellurides Conversion Mechanism Toward Ultralong-Lifespan Potassium Ion Storage.

Abstract

Transition metal tellurides (TMTes) are promising anodes for potassium-ion batteries (PIBs) due to their high theoretical specific capacity and impressive electronic conductivity. Nevertheless, TMTes suffer from persistent capacity degradation due to the large volume expansion, high ion-diffusion energy barriers, and the dissolution/shuttle of potassium polytellurides (K_xTe_y). Herein, a heterostructured CoTe₂ composite equipped with a self-catalytic center (N-CoTe₂/LTTC) is developed, exploiting its low-tortuosity tunneling, chemical tunability, and self-catalytic properties to elevate cycling stability to new heights. Systematic experiments have verified that the elaborate N-CoTe₂/LTTC provides a short-range and efficient electron/ion transport path, accelerates K⁺ diffusion kinetics, and suppresses huge volume distortion. Notably, the N─Co bonds self-catalytic center can promote the adsorption capabilities and accelerate the conversion kinetics for K_xTe_y under the synergistic effect of heterojunction. Consequently, the optimized N-CoTe₂/LTTC electrode delivers an ultralong‑lifespan cyclability (over 25 000 cycles at 2.0 A g^-1, only 0.0019% capacity decay rate per cycle), outperforming those of reported Te-based anodes. Finally, the N-CoTe₂/LTTC//PTCDA@450 full cell manifests impressive stability (over 4300 cycles at 2.0 A g^-1). This work uncovers the impact of catalytic centers on the conversion of K_xTe_y and provides valuable insights for rationally designing ultralong-lifespan TMTes anodes for PIBs.