Novel K(2)Ti(8)O(17) Anode via Na(+)/Al(3+) Co-Intercalation Mechanism for Rechargeable Aqueous Al-Ion Battery with Superior Rate Capability

A promising aqueous aluminum ion battery (AIB) was assembled using a novel layered K(2)Ti(8)O(17) anode against an activated carbon coated on a Ti mesh cathode in an AlCl(3)-based aqueous electrolyte. The intercalation/deintercalation mechanism endowed the layered K(2)Ti(8)O(17) as a promising anode for rechargeable aqueous AIBs. NaAc was introduced into the AlCl(3) 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(−1). 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(+)/Al(3+) ions in the aqueous AIB. The results indicated that the layered structure facilitated the intercalation/deintercalation of Na(+)/Al(3+) ions, thus providing a high-rate performance of the K(2)Ti(8)O(17) anode. The diffusion-controlled electrochemical characteristics and the reduction of Ti(4+) species during the discharge process illustrated the intercalation/deintercalation mechanism of the K(2)Ti(8)O(17) anode. This study provides not only insight into the charge–discharge mechanism of the K(2)Ti(8)O(17) anode but also a novel strategy to design rechargeable aqueous AIBs.