Orthorhombic Cobalt Ditelluride with Te Vacancy Defects Anchoring on Elastic MXene Enables Efficient Potassium‐Ion Storage

Abstract

The fast and reversible potassiation/depotassiation of anode materials remains an elusive yet intriguing goal. Herein, a class of the P‐doping‐induced orthorhombic CoTe2 nanowires with Te vacancy defects supported on MXene (o‐P‐CoTe2/MXene) is designed and prepared, taking advantage of the synergistic effects of the conductive o‐P‐CoTe2 arrays with rich Te vacancy defects and the elastic MXene sheets with self‐autoadjustable function. Consequently, the o‐P‐CoTe2/MXene superstructure exhibits boosted potassium‐storage performance, in terms of high reversible capacity (373.7 mAh g−1 at 0.2 A g−1 after 200 cycles), remarkable rate capability (168.2 mAh g−1 at 20 A g−1), and outstanding long‐term cyclability (0.011% capacity decay per cycle over 2000 cycles at 2 A g−1), representing the best performance in transition‐metal‐dichalcogenides‐based anodes to date. Impressively, the flexible full battery with o‐P‐CoTe2/MXene anode achieves a satisfying energy density of 275 Wh kg−1 and high bending stability. The kinetics analysis and first‐principles calculations reveal superior pseudocapacitive property, high electronic conductivity, and favorable K+ ion adsorption and diffusion capability, corroborating fast K+ ion storage. Especially, ex situ characterizations confirm o‐P‐CoTe2/MXene undergoes reversible evolutions of initially proceeding with the K+ ion insertion, followed by the conversion reaction mechanism.

Interface-Engineered Fe3O4/MXene Heterostructures for Enhanced Lithium-Ion Storage

“…The low R ct value in the case of Fe 3 O 4 /MXene-7 reflects the hybrid system’s capability to support faster electron transportation, thereby resulting in improved rate capability. Moreover, a higher slope of the straight line was observed for Fe 3 O 4 /MXene-7, indicating its better Li + diffusion capability …”

Homologous MXene‐Derived Electrodes for Potassium‐Ion Full Batteries

“…To ensure a suitable cathode-to-anode capacity ratio for proper cell balance, a cathode-limited configuration was chosen with a cathode-to-anode mass loading ratio of 1:1. [37,38] The capacity and energy density were calculated based on the mass of cathodes. [39,40] The galvanostatic charge/discharge (GCD) tests were measured on a Land battery tester (CT200A).…”

P‐Doped NiTe2 with Te‐Vacancies in Lithium–Sulfur Batteries Prevents Shuttling and Promotes Polysulfide Conversion

“…The density-of-states patterns indicated that P⊂NiTe 2−x had strong metallic features because of continuous electronic states at the Fermi level, accompanied by increasing density-of-states intensities relative to those for NiTe 2−x and NiTe 2 (Figure S12b, Supporting Information). [33] High-resolution Ni 2p X-ray photoelectron spectroscopy (XPS) of MSC/NiTe 2 was deconvoluted into two bonds at 873.3 eV (2p 1/2 ) and 855.6 eV (2p 3/2 ), revealing the presence of Ni 2+ (Figure 3d). Ni (2p) satellite peaks at 881.3 and 861.3 eV, attributed to the Ni (d8) orbital, confirmed bivalent Ni in NiTe 2 .…”