Novel KTiO Anode via Na/Al 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 KTiO anode against an activated carbon coated on a Ti mesh cathode in an AlCl-based aqueous electrolyte. The intercalation/deintercalation mechanism endowed the layered KTiO as a promising anode for rechargeable aqueous AIBs. NaAc was introduced into the AlCl 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. 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 ions in the aqueous AIB. The results indicated that the layered structure facilitated the intercalation/deintercalation of Na/Al ions, thus providing a high-rate performance of the KTiO anode. The diffusion-controlled electrochemical characteristics and the reduction of Ti species during the discharge process illustrated the intercalation/deintercalation mechanism of the KTiO anode. This study provides not only insight into the charge-discharge mechanism of the KTiO anode but also a novel strategy to design rechargeable aqueous AIBs.