Te-vacancy-rich CoTe2−x anodes for efficient potassium-ion storage

Metal tellurides (MTes) have emerged as highly promising anode materials for potassium-ion batteries (PIBs) due to their exceptional volumetric capacity and superior electronic conductivity. The practical application of MTes, however, faces challenges such as slow kinetics, volumetric effects, and ill-defined shuttling phenomena of K-polytellurides (K-pTex). Herein, we present a groundbreaking solution through the development of Te-vacancy-rich CoTe2−x nanoparticles confined within a 3D honeycomb-like, hollow hierarchical gridded porous structured, S, N co-doped dual-carbon structural composite (CoTe2−x@3DPSNDC) via facile defect chemistry. This well-designed composite offers an unparalleled combination of fast ion/electron transport and stable K-pTex, propelling battery reactions to new heights. State-of-the-art in-/ex-situ techniques and density functional theory calculations reveal the evolution and shuttling mechanism of K-pTex. Remarkably, our study validates the exceptional physical confinement and chemisorption capabilities of S, N co-doped dual-type carbon skeletons on K5Te3 and K2Te3, leading to ultra-stable potassium-ion storage. Furthermore, the Te vacancies substantially boost the intrinsic conductivity of CoTe2−x, resulting in accelerated reaction kinetics and enhanced rate performance of the CoTe2−x@3DPSNDC electrode which achieved an impressive capacity of 508.1 mAh cm−3 at 5.0 A g−1. Our advanced design concept provides unique insights into the construction of MTes anodes for achieving stable cyclability and fast-charging PIBs.