Lattice Expanded Titania as an Excellent Anode for an Aqueous Zinc-Ion Battery Enabled by a Highly Reversible H+-Promoted Zn2+ Intercalation

Aqueous Zn-ion batteries have garnered significant attention as promising and safe energy storage systems. Due to the inevitable dendrite and corrosion in metallic Zn anodes, alternative anodes of intercalation-type materials are desirable, but they still suffer from low energy efficiency, unsatisfactory capacity, and insufficient cycle life. Here, we develop a high-performance anode for aqueous Zn-ion batteries via a lattice expansion strategy in combination with a Zn2+/H+ synergistic mechanism. The anatase TiO2 with expanded lattice exhibits an appropriate deintercalation potential of 0.18 V vs Zn/Zn2+ and a high reversible capacity (227 mAh g–1 at 2.04 A g–1) with an outstanding rate capability and excellent cycle stability. The high electrochemical performance is attributed to a decrease in the Zn2+/H+ diffusion barriers, which results from lattice expansion and also a H+-promoted Zn2+ intercalation effect. The anode intercalates Zn2+/H+ via a solid-solution mechanism with a minor volume change, which contributes to the high reversibility and thus high energy efficiency. When paired with different types of cathodes, including NV, I2, and activated carbon, to construct corresponding full cells, high specific energy, high specific power, long cycle life, and extremely high energy efficiency can be achieved. This study provides a prospect for developing high-performance Zn-ion batteries.