Quantitative Regulation of Interlayer Space of NH4 V4 O10 for Fast and Durable Zn2+ and NH4 + Storage

Abstract

Layered vanadium-based oxides are the promising cathode materials for aqueous zinc-ion batteries (AZIBs). Herein, an in situ electrochemical strategy that can effectively regulate the interlayer distance of layered NH₄ V₄ O₁₀ quantitatively is proposed and a close relationship between the optimal performances with interlayer space is revealed. Specifically, via increasing the cutoff voltage from 1.4, 1.6 to 1.8 V, the interlayer space of NH₄ V₄ O₁₀ can be well-controlled and enlarged to 10.21, 11.86, and 12.08 Å, respectively, much larger than the pristine one (9.5 Å). Among them, the cathode being charging to 1.6 V (NH₄ V₄ O₁₀ -C1.6), demonstrates the best Zn²⁺ storage performances including high capacity of 223 mA h g^-1 at 10 A g^-1 and long-term stability with capacity retention of 97.5% over 1000 cycles. Such superior performances can be attributed to a good balance among active redox sites, charge transfer kinetics, and crystal structure stability, enabled by careful control of the interlayer space. Moreover, NH₄ V₄ O₁₀ -C1.6 delivers NH₄ ⁺ storage performances whose capacity reaches 296 mA h g^-1 at 0.1 A g^-1 and lifespan lasts over 3000 cycles at 5 A g^-1 . This study provides new insights into understand the limitation of interlayer space for ion storage in aqueous media and guides exploration of high-performance cathode materials.

Keywords: ammonium vanadate; aqueous ammonium-ion batteries; aqueous zinc-ion batteries; interlayer space; layered structure.

Figure 1

a) Schematic illustration of the preparation procedure for NH₄V₄O₁₀ nanoribbon. b) X‐ray diffraction pattern of the as‐prepared NH₄V₄O₁₀. c) V 2p XPS spectrum of the as‐prepared NH₄V₄O₁₀. d) Schematic crystal structure of the NH₄V₄O₁₀. e,f) SEM, and g) HRTEM images of NH₄V₄O₁₀ nanoribbon with SAED in the inset.

Figure 2

The initial galvanostatic charge and discharge profiles of NH₄V₄O₁₀ in the voltage range of a) 0.2–1.4 V, b) 0.2–1.6 V, c) 0.2–1.8 V. d) Ex situ XRD, e) XPS, and f) HRTEM patterns of the NH₄V₄O₁₀ electrode at different state of charge. g) Schematic crystal structure patterns of the electrode at different state of charge.

Figure 3

a) CV profiles of NH₄V₄O₁₀ in the voltage range of 0.2–1.4,1.6, and 1.8 V at a scan rate of 0.2 mV s⁻¹. b) Galvanostatic charge and discharge profiles of NH₄V₄O₁₀ in the voltage range of 0.2–1.4, 1.6, and 1.8 V at a current density of 0.1 A g⁻¹. c) Cycle performance of NH₄V₄O₁₀ in 0.2–1.4, 1.6, and 1.8 V at 0.1 A g⁻¹. d) Ex situ XRD of the NH₄V₄O₁₀ electrode between different voltage range after 1000 cycles. e) Long cycle performance of NH₄V₄O₁₀ in 0.2–1.4, 1.6, and 1.8 V at 10 A g⁻¹ after pre‐cycling for three cycles at 0.1 A g⁻¹.

Figure 4

a) Rate performance of NH₄V₄O₁₀ in the voltage range of 0.2–1.4, 1.6, and 1.8 V. b) The rate performance comparison of NH₄V₄O₁₀ in 0.2–1.6 V versus state‐of‐the‐art materials.^{[ 25} , ²⁶ , ²⁷ , ²⁸ , ²⁹ , ³⁰ , ^{31 ]} The b‐values of NH₄V₄O₁₀ electrode between c) 0.2 and 1.4 V, d) 0.2 and 1.6 V, e) 0.2 and 1.8 V. f) The capacity contribution of NH₄V₄O₁₀ at different scan rates between the three voltage ranges. g) Nyquist plots of the impedance spectra of NH₄V₄O₁₀ electrode at different charge state.

Figure 5

Electrochemical performance of NH₄V₄O₁₀ in 5 m (NH₄)₂SO₄ electrolyte: a) GCD curves at the current density of 0.1 A g⁻¹. b) Rate capability of NH₄V₄O₁₀ at a current density from 0.1 to 5 A g⁻¹. c) Cycle performance at 1 A g⁻¹. d) Long cycle performance at 5 A g⁻¹. e) Comparison of NH₄V₄O₁₀ versus state‐of‐the‐art materials for NH₄ ⁺ storage in the current density of 0.1 A g⁻¹.^{[ 39} , ⁴⁰ , ⁴¹ , ⁴² , ⁴³ , ⁴⁴ , ^{45 ]}

Figure 6

Ex situ a) XRD. b) FTIR patterns of NH₄V₄O₁₀ in NH₄ ⁺ battery. c) V 2p and d) O 1s of ex situ XPS spectrums of NH₄V₄O₁₀ in NH₄ ⁺ battery.