Hydrated titanic acid as an ultralow-potential anode for aqueous zinc-ion full batteries

Abstract

• An ultralow-potential H 2 Ti 3 O 7 ·xH 2 O anode is first introduced for zinc-ion batteries. • The storage mechanism of H + and Zn 2+ co-insertion is demonstrated on the H 2 Ti 3 O 7 ·xH 2 O anode. • The H 2 Ti 3 O 7 ·xH 2 O anode features excellent electrochemical performance. • The assembled Zn x MnO 2 //H 2 Ti 3 O 7 ·xH 2 O full battery exhibits the high output voltage. Developing the alternative anode materials that can completely resolve the dendrite concern of Zn metal anodes are desirable for reliable aqueous zinc-ion batteries. However, the sub-optimal charging potentials of reported anodes inevitably cause the discounted output voltage and energy density on a zinc-ion full battery. Herein, it is firstly demonstrated that the hydrated titanic acid (H 2 Ti 3 O 7 ·xH 2 O) can be applied as an ultralow-potential anode for the aqueous zinc-ion full battery. The depressed potential (0.2 V vs. Zn 2+ /Zn) of the H 2 Ti 3 O 7 ·xH 2 O compared to that of reported candidates could significantly enhance the operating voltage level of the zinc-ion full battery. Furthermore, the comprehensive analyses demonstrate that the expanded lattice spacings and interlayer crystal water stimulate Zn 2+ along with H + to jointly insert and extract on the H 2 Ti 3 O 7 ·xH 2 O anode. The low-potential H 2 Ti 3 O 7 ·xH 2 O anode exhibits an impressive cycling performance and coulombic efficiency by virtue of the assistance from interlayer crystal water. The assembled Zn x MnO 2 //H 2 Ti 3 O 7 ·xH 2 O zinc-ion full battery delivers the decent electrochemical performance, especially a high output voltage of over 1 V. This low-potential, high-stable H 2 Ti 3 O 7 ·xH 2 O anode reveals the exceptional potential for aqueous zinc-ion full batteries.