| Summary: | A promising aqueous aluminum ion battery (AIB) was assembled using a novel layered K<sub>2</sub>Ti<sub>8</sub>O<sub>17</sub> anode against an activated carbon coated on a Ti mesh cathode in an AlCl<sub>3</sub>-based aqueous electrolyte. The intercalation/deintercalation mechanism endowed the layered K<sub>2</sub>Ti<sub>8</sub>O<sub>17</sub> as a promising anode for rechargeable aqueous AIBs. NaAc was introduced into the AlCl<sub>3</sub> aqueous electrolyte to enhance the cycling stability of the assembled aqueous AIB. The as-designed AIB displayed a high discharge voltage near 1.6 V, and a discharge capacity of up to 189.6 mAh g<sup>−1</sup>. The assembled AIB lit up a commercial light-emitting diode (LED) lasting more than one hour. Inductively coupled plasma–optical emission spectroscopy (ICP-OES), high-resolution transmission electron microscopy (HRTEM), and X-ray absorption near-edge spectroscopy (XANES) were employed to investigate the intercalation/deintercalation mechanism of Na<sup>+</sup>/Al<sup>3+</sup> ions in the aqueous AIB. The results indicated that the layered structure facilitated the intercalation/deintercalation of Na<sup>+</sup>/Al<sup>3+</sup> ions, thus providing a high-rate performance of the K<sub>2</sub>Ti<sub>8</sub>O<sub>17</sub> anode. The diffusion-controlled electrochemical characteristics and the reduction of Ti<sup>4+</sup> species during the discharge process illustrated the intercalation/deintercalation mechanism of the K<sub>2</sub>Ti<sub>8</sub>O<sub>17</sub> anode. This study provides not only insight into the charge–discharge mechanism of the K<sub>2</sub>Ti<sub>8</sub>O<sub>17</sub> anode but also a novel strategy to design rechargeable aqueous AIBs.
|
|---|