Aqueous vs. nonaqueous Zn-ion batteries: consequences of the desolvation penalty at the interface

Author(s): Dipan Kundu ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵ , Shahrzad Hosseini Vajargah ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵ , Liwen Wan ⁶ ^, ⁷ ^, ⁸ ^, ⁹ ^, ¹⁰ , Brian Adams ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵ , David Prendergast ⁶ ^, ⁷ ^, ⁸ ^, ⁹ ^, ¹⁰ , Linda F. Nazar ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵

Publication date (Electronic): 2018

Journal: Energy & Environmental Science

Publisher: Royal Society of Chemistry (RSC)

Read this article at

ScienceOpenPublisher

Bookmark

There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

Abstract

Comparison of intercalation of Zn ²⁺ in layered V ₃O ₇·H ₂O in non-aqueous and aqueous electrolytes reveals a much higher desolvation penalty at the non-aqueous interface, a major factor in dictating the kinetics.

Abstract

Zinc ion batteries using metallic zinc as the negative electrode have gained considerable interest for electrochemical energy storage, whose development is crucial for the adoption of renewable energy technologies, as zinc has a very high volumetric capacity (5845 mA h cm ⁻³), is inexpensive and compatible with aqueous electrolytes. However, the divalent charge of zinc ions, which restricts the choice of host material due to hindered solid-state diffusion, can also pose a problem for interfacial charge transfer. Here, we report our findings on reversible intercalation of up to two Zn ²⁺ ions in layered V ₃O ₇·H ₂O. This material exhibits very high capacity and power (375 mA h g ⁻¹ at a 1C rate, and 275 mA h g ⁻¹ at an 8C rate) in an aqueous electrolyte compared to a very low capacity and slow rate capabilities in a nonaqueous medium. Operando XRD studies, together with impedance analysis, reveal solid solution behavior associated with Zn ²⁺-ion diffusion within a water monolayer in the interlayer gap in both systems, but very sluggish interfacial charge transfer in the nonaqueous electrolyte. This points to desolvation at the interface as a major factor in dictating the kinetics. Temperature dependent impedance studies show high activation energies associated with the nonaqueous charge transfer process, identifying the origin of poor electrochemical performance.