Efficient Polytelluride Anchoring for Ultralong-Life Potassium Storage: Combined Physical Barrier and Chemisorption in Nanogrid-in-Nanofiber.

Metal tellurides (MTes) are highly attractive as promising anodes for high-performance potassium-ion batteries. The capacity attenuation of most reported MTe anodes is attributed to their poor electrical conductivity and large volume variation. The evolution mechanisms, dissolution properties, and corresponding manipulation strategies of intermediates (K-polytellurides, K-pTe) are rarely mentioned. Herein, we propose a novel structural engineering strategy to confine ultrafine CoTe nanodots in hierarchical nanogrid-in-nanofiber carbon substrates (CoTe@NC@NSPCNFs) for smooth immobilization of K-pTe and highly reversible conversion of CoTe by manipulating the intense electrochemical reaction process. Various in situ/ex situ techniques and density functional theory calculations have been performed to clarify the formation, transformation, and dissolution of K-pTe (KTe and KTe), as well as verifying the robust physical barrier and the strong chemisorption of KTe and KTe on S, N co-doped dual-type carbon substrates. Additionally, the hierarchical nanogrid-in-nanofiber nanostructure increases the chemical anchoring sites for K-pTe, provides sufficient volume buffer space, and constructs highly interconnected conductive microcircuits, further propelling the battery reaction to new heights (3500 cycles at 2.0 A g). Furthermore, the full cells further demonstrate the potential for practical applications. This work provides new insights into manipulating K-pTe in the design of ultralong-cycling MTe anodes for advanced PIBs.