Electrochemically active silver molybdenum oxyfluoride perovskite: Synthesis and in situ electrochemical characterization

Amatucci

2016

J. Electrochem. Soc.

Sodium ion batteries are a topic of emerging interest, as the low cost and high natural abundance of sodium precursors provide a specific advantage over commercial lithium ion batteries. Comparatively, sodium chemistries suffer from lower operating voltages, making the development of suitable high voltage positive electrodes key to enabling sodium chemistries capable of direct replacement for modern lithium ion storage devices. Herein, we investigate dis/ordered nickel doped manganese spinels (Na x Mn 2-y Ni y O 4 ) as a positive electrode for sodium ion battery applications. Due to the kinetic limitations of the sodium de/insertion reaction into Na 1-x Mn 2-y Ni y O 4 the effect of both temperature and the electrochemical cycling window are studied revealing a unique reaction pathway and potential optimization routes for further study. Increasing interest in large-scale electrochemical energy storage for grid applications has prompted the investigation of battery chemistries that are more cost-effective as compared to commercial Li-ion technology. Due to the large abundance and associated low costs of sodium precursors, sodium-ion batteries have been widely investigated over recent years. Investigations into positive electrodes for sodium ion batteries (SIBs) have produced a number of different electrode chemistries capable of reversible Na + de/insertion. In particular, the manganese oxides have demonstrated a number of possible host structures suitable for reversible cycling of Na + , with the majority of attention being generally confined to layered compounds consisting of transition metal doped P2, P3, and O3 type structures. 1-4However, there still remain certain drawbacks in utilizing such SIBs for commercial applications, as reversible Na + de/insertion requires large open structures due to the physically larger ionic radii of Na + (∼1.0 Å) relative to that of Li + (0.59 Å). 5Of particular concern is the lower voltage of SIBs using traditional chemistries imparted by the Na/Na + redox, which is approximately 0.33 V higher than that of Li/Li + . Table I considers a competitive analysis of various cathode chemistries of potential interest for SIBs, and although suffering from a reduction in gravimetric and volumetric capacity when comparing against LIBs, movement from lithium to sodium chemistries offers considerable advantages in terms of cost and raw material abundance making them far more practical for electrical grid applications.Due to the large foundation of research on lithium-ion cathode materials, it is desirable to potentially utilize such promising structures for analogous cathodes in SIBs. The spinel structure has been widely studied, and offers facile Li + de/insertion by nature of the 3D interdiffusional pathways. However, the large ionic size differences between Li + and Na + have demonstrated considerable difficulty in the implementation of sodium analogues to existing Li-based compositions; yet the spinel structure has proven to successfully accommodate Na + following initial delithiation ...

Section: Methodsmentioning

confidence: 99%

NaMn_2-xNi_xO₄Derived from Mesoporous LiMn_2-xNi_xO₄: High-Voltage Spinel Cathode Materials for Na-Ion Batteries

Amatucci

2016

J. Electrochem. Soc.

Section: Methodsmentioning

confidence: 99%

“…The cell parts and cathodes were dried under vacuum at 120 °C prior to assembly to remove residual moisture. Cell assembly was performed as described in earlier work . Prior to in situ and operando XRD measurements, the 3-axis stage was aligned with the incident X-ray beam to optimize the signal-to-noise ratio of the (1,1,1) spinel reflection.…”

Section: Methodsmentioning

confidence: 99%

“…Cell assembly was performed as described in earlier work. 47 Prior to in situ and operando XRD measurements, the 3-axis stage was aligned with the incident X-ray beam to optimize the signalto-noise ratio of the (1,1,1) spinel reflection. Although the concentration of Li + in the prepared sodium cells was extremely low after delithiation (∼1 mol %), fresh sodium anodes and electrolyte were provided in rebuilt Na/Na + cells after the initial delithiation step to ensure the following intercalation studies are free of any mixed Li + /Na + intercalation effects.…”

Section: Methodsmentioning

confidence: 99%

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Structural and Electrochemical Investigation of Na⁺ Insertion into High-Voltage Spinel Electrodes

Amatucci

2015

Chem. Mater.

The emerging interest in Na + -ion batteries should increase the relative importance of higher voltage positive electrodes as a response to the lower voltage imparted by the Na/Na + redox reaction relative to that of Li/Li + . The 4.7 V LiMn 1.5 Ni 0.5 O 4 spinel is already an attractive candidate for high-voltage lithium-ion positive electrodes, and its host structure, λ-Mn 0.75 Ni 0.25 O 2 , could be of even greater importance for Na batteries. The electrochemical and structural characteristics of higher-voltage Na x Mn 1.5 Ni 0.5 O 4 relative to Na x Mn 2 O 4 during ion insertion are investigated for the first time. High-resolution electrochemistry, coupled with in situ and ex situ X-ray diffraction, is utilized to provide initial insights into the mechanism of Na + insertion. Distinct electrochemical challenges brought forth by Na + ion insertion into the spinel structure are also discussed in detail.

“…Metal oxyfluoride compounds have also been evaluated as some of the promising high‐capacity conversion cathodes for RSBs . Previous studies on iron oxyfluoride electrodes for LIBs revealed that a small amount of oxygen doping in the fluoride structure is effective for improving the electronic conductivity and reversible capacity . Based on this concept, Zhou et al first examined the electrochemical activities of FeO 0.7 F 1.3 as a cathode for RSBs .…”

Section: Cathode Materials With Conversion Reaction For Na Storagementioning

confidence: 99%

Conversion‐Based Cathode Materials for Rechargeable Sodium Batteries

Advanced Energy Materials

Kang

2018

Conversion‐based electrode materials for rechargeable sodium batteries (RSBs) have received considerable attention because of their potentially higher energy densities than those of conventional intercalation‐based electrode materials. This would overcome generally lower energy densities of RSBs than those of lithium‐ion batteries. However, they often suffer from large volume changes, sluggish Na‐ion kinetics, and large overpotential in their reaction. Intensive research has thus focused on improving the electrochemical performance through a number of approaches, including analyses of the reaction mechanisms during charge/discharge, engineering the electrode materials in terms of their nanostructuring or compositing, and searching for new candidate materials. This review presents an overview of the approaches used to explore conversion electrode materials for RSBs, in particular focusing on those with relative high redox potential that could be possibly used as cathodes, followed by a discussion of the challenges and perspectives involving future research directions for these materials.