Tubular design and metal ratio refinement of copper telluride electrodes for superior volumetric capacity in potassium-ion batteries

Despite encountering various challenges in the production of high volumetric capacity potassium-ion batteries (PIBs), metal tellurides present a promising solution owing to their high density and conductivity. In this work, we synthesized copper telluride nanotubes, measuring 2–5 μm in length with a wall thickness of 30 nm, employing a two-step hot injection method as anode materials for high volumetric capacity PIBs. Their electrochemical behavior was investigated via in-situ X-ray diffraction (XRD), elucidating the precipitation of metallic copper during K+ insertion. Through meticulous adjustment of the copper content, exceptional volumetric capacity (2225.1 mA h cm−3) and impressive rate capacity (994 mA h cm−3) were ultimately attained. Notably, the material exhibited over 150 cycles at a current density of 500 mA h g−1 with negligible capacity degradation. This work underscores the significance of the tellurium-to‑copper ratio, demonstrating that a 2:1 ratio is pivotal for optimizing tellurium utilization and enhancing electrode rate performance. Moreover, the nanotubes structure substantially augmented the reactive surface area while mitigating issues associated with volume expansion. These discoveries position copper telluride nanotubes as robust contenders for the next generation of high-capacity PIBs anode. CuTe nanotubes offer enhanced volumetric capacity due to their high-density design, increased surface area from their tubular structure for efficient potassiation, and improved conductivity from copper exsolution. The integration of the tube with elements like copper and polytelluride further elevates electrochemical performance. [Display omitted] •The copper telluride was synthesized using the cation exchange method with various copper ratios.•The in-situ exsolution of metallic copper significantly enhanced the utilization of polytelluride.•The remarkable volumetric capacity of 2225.1 mA h cm−3 was achieved.•The tubular nanostructure design played a crucial role in accelerating the sluggish potassium kinetic.