Regulating Zn Deposition via an Artificial Solid-Electrolyte Interface with Aligned Dipoles for Long Life Zn Anode

Abstract

Highlights:

1. An artificial solid–electrolyte interface composed of a perovskite type material, BaTiO₃, is introduced to Zn anode surface in aqueous zinc ion batteries.

2. The BaTiO₃ layer endowing inherent character of the switched polarization can regulate the interfacial electric field at anode/electrolyte interface.

3. Zn dendrite can be restrained, and Zn metal batteries based on BaTiO₃ layer show stable cycling.

Abstract: Aqueous zinc ion batteries show prospects for next-generation renewable energy storage devices. However, the practical applications have been limited by the issues derived from Zn anode. As one of serious problems, Zn dendrite growth caused from the uncontrollable Zn deposition is unfavorable. Herein, with the aim to regulate Zn deposition, an artificial solid–electrolyte interface is subtly engineered with a perovskite type material, BaTiO₃, which can be polarized, and its polarization could be switched under the external electric field. Resulting from the aligned dipole in BaTiO₃ layer, zinc ions could move in order during cycling process. Regulated Zn migration at the anode/electrolyte interface contributes to the even Zn stripping/plating and confined Zn dendrite growth. As a result, the reversible Zn plating/stripping processes for over 2000 h have been achieved at 1 mA cm⁻² with capacity of 1 mAh cm⁻². Furthermore, this anode endowing the electric dipoles shows enhanced cycling stability for aqueous Zn-MnO₂ batteries. The battery can deliver nearly 100% Coulombic efficiency at 2 A g⁻¹ after 300 cycles.

Supplementary Information: The online version of this article (10.1007/s40820-021-00599-2).

Keywords: Artificial solid–electrolyte interface; Perovskite type dielectric material; Regulated Zn deposition; Zn anode; Zn ion battery.

Fig. 1

Schematic of zinc ion transport during Zn stripping/plating for: a bare Zn, b BTO@Zn foil. c Schematic diagram of the Ti ion migration in the [TiO₆] octahedral interstitial sites under the external electric field. d Schematic of the mechanism of zinc ion transport at the BTO@Zn/electrolyte interface during Zn plating process. Schematic illustration of the BTO@Zn surface used in the simulation: e side view, f top view. The bottom two Zn layers are fixed during the geometrical optimization. Ba, Ti, O, Zn atoms are represented by green, blue, red, gray spheres, respectively. g Differential charge density (ρ_diff = ρ_BTO@Zn – ρ_BTO – ρ_Zn) of the BTO@Zn surface. Yellow and blue surfaces indicate the electron gain and loss, respectively. h Schematic diagram of zinc ion transport at the Zn anode/electrolyte interface during Zn plating process

Fig. 2

Cycling performance of the symmetric cells with Zn and BTO@Zn, respectively: a at 1 mA cm⁻² with capacity of 1 mAh cm⁻² and b at 5 mA cm⁻² with capacity of 2.5 mAh cm⁻². The insets reveal the detailed corresponding voltage profiles at various current densities and different cycles

Fig. 3

SEM images of the anode morphology: a–c bare Zn and d–f BTO@Zn foils. a, d before and b, c and e, f after 100 cycles at 1 mA cm⁻² and 1 mAh cm⁻² of the symmetric cells. Highlight typical cross section SEM images in c and f. BTO layer, deposited Zn and Zn foils are separated by the yellow lines. (Color figure online)

Fig. 4

Electrochemical performance of Zn–MnO₂ batteries based on bare Zn and BTO@Zn foil, respectively. a CV profiles of the 2nd cycle at 1 mV s⁻¹. b GCD curves of the 2nd discharge process at 200 mA g⁻¹. c Cycling performance at 2 A g⁻¹