Novel One-Dimensional Hollow Carbon Nanotubes/Selenium Composite for High-Performance Al-Se Batteries

Herein, we successfully prepared one-dimensional nanowire with carbon-coated selenium (Se@CW) by using a simple wet chemical method and obtained a one-dimensional hollow Se@C nanotube (Se@CT) after the subsequent calcination treatment. We have formed a new Al-Se secondary battery by using Se@CT as the cathode and metal aluminum as the anode in the AlCl₃/[EMIm]Cl electrolyte. It is believed that the oxidation intermediate of Se in Al-Se batteries may not only have Se₂²⁺, but there may be other oxidation intermediates, such as Se⁴⁺, Se²⁺, and Se₈²⁺. Therefore, Se@CT exhibits excellent charge-discharge performance in Al-Se batteries. Its initial discharge capacity reaches 447.2 mA h g^-1 at 200 mA g^-1, and the operating voltage is above 1.6 V. Its energy density approaches 708.8 W h k g^-1, the capacity is still 162.9 mA h g^-1 after 200 cycles at 500 mA g^-1, and the corresponding capacity retention rate is up to 83.5%. In addition, its electrochemical performance is far superior to that of Se@CMK-3 in Al-Se batteries and the electrochemical properties of carbon materials, oxides, and sulfide electrode materials in some aluminum-ion batteries, which will open up a new direction for the development of new secondary aluminum-based batteries.