Rechargeable Aqueous Lithium-Ion Battery of TiO2∕LiMn2O4 with a High Voltage

Rechargeable aqueous TiO2/LiMn2O4 lithium-ion battery is fabricated by combining the TiO2 nanotube arrays on metallic titanium foil as anode and LiMn2O4 as cathode in aqueous solution with mixed lithium salts (LiCl and Li2SO4). It is shown from cyclic voltammograms that the lithium insertion/extraction peaks of the cathode are highly symmetrical before the oxygen evolution, which can ensure a good lithium utilization of the LiMn2O4. Importantly, a higher anodic hydrogen evolution overpotential in TiO2 anode is observed, which is essential for the facile lithium insertion in preference to the hydrogen evolution. Meanwhile, the gas (hydrogen and oxygen) evolution in the anodic and cathodic processes can be effectively suppressed in aqueous electrolyte with mixed lithium salts as compared with that in pure LiCl and Li2SO4 solution, respectively. Correspondingly, the fabricated TiO2/LiMn2O4 battery presents a high discharge voltage plateau of above 2 V, which is well beyond the average discharge voltage of current aqueous battery system. Therefore, the combination of the appropriate anode/cathode-active materials with a relatively large potential difference and high gas evolution overpotential is an ideal strategy for developing new aqueous battery system based on reversible lithium insertion/extraction reactions in aqueous electrolyte.