One-dimensional CoTe2 nanorods combined with an optimal carbon layer for fast and robust potassium storage

Abstract

CoTe₂ as a high-performance anode material for potassium ion batteries still faces a lot of challenges that hinder its electrochemical performance, including poor intrinsic electronic conductivity, slow reaction kinetics, and significant volume changes during charging and discharging processes. To address these issues, one-dimensional CoTe₂ nanorods were synthesized using a one-step hydrothermal method and then coated with a carbon layer to form CoTe₂@C nanocomposites. The resulting composite exhibited a significant interaction between CoTe₂ and the carbon layer, resulting in the formation of a stable heterostructure. This interaction not only improved the electrical conductivity of the composites but also facilitated the migration of electrons and K⁺ ions. When used as the anode for potassium ion batteries, the CoTe₂@C anode demonstrated enhanced electrochemical performance. At a current density of 0.5 A g⁻¹, the CoTe₂@C anode exhibited a reversible capacity of 100.3 mA h g⁻¹ after 1000 cycles. Even at a higher current density of 1.0 A g⁻¹, it maintained a high reversible capacity of 72.5 mA h g⁻¹ after 3000 cycles. Furthermore, it displayed excellent rate capability, with an average reversible capacity of 98.0 mA h g⁻¹ at a high rate of 5.0 A g⁻¹, showing a potential application capability for potassium ion batteries.