Oxygen Reduction Contributing to Charge Transfer during the First Discharge of the CeO₂–Bi₂Fe₄O₉–Li Battery: In Situ X-ray Diffraction and X-ray Absorption Near-Edge Structure Investigation

Abstract

Since pioneering work performed by Rouxel et al. that emphasizes the effects of anions in the ionic intercalation process, the role of oxygen ions in lithium ionic battery electrodes is of great interest since it will give new directions to further enhance the battery capacity. In this paper, Bi2Fe4O9–CeO2 was synthesized and was used as an anode for second lithium batteries application. A large amount of oxygen vacancies exist in both CeO2 and Bi2Fe4O9. In CeO2, oxygen vacancies are mainly located at the 111 plane, and in Bi2Fe4O9, oxygen vacancies are mainly located at the 002 plane. Li+ insertion into Bi2Fe4O9 produced high spin tetrahedral Fe2+, which is Jahn–Teller active and induces shrinkage of the Bi2Fe4O9 lattice and releases O2. The released O2 is further reduced and contributes to ∼70 mAh/g during the first discharge process. The 002 plane of Bi2Fe4O9 is very reactive for oxygen reduction, where there are not only a lot of oxygen vacancies but also tetrahedral Fe3+ ions participating in producing more oxygen vacancies. This work gives new directions for future design of lithium battery electrodes, which can reversibly evolve/reduce O2, and the O2/O2– (or O–) redox couple is responsible for charge transfer.

Facile Construction of Novel 3-Dimensional Graphene/Amorphous Porous Carbon Hybrids with Enhanced Lithium Storage Properties

“…Although Bi 2 O 3 , BiFeO 3 , and Bi 2 Fe 4 O 9 –CeO 2 − have large discharge capacities and are of great interest for lithium battery applications, with a Bi ionic oxidation state of +3, these compounds usually display a discharge voltage lower than 2 V and are only suitable for anode applications. Bi ions in bismuth oxides can have higher oxidation state (+5) − and can enhance the electrochemical discharge.…”

In Situ Studies of 30% Li-Doped Bi25FeO40 Conversion Type Lithium Battery Electrodes

“…30% Li-doped Bi 25 FeO 40 was synthesized using a co-precipitation route. , Typically, stoichiometric amount of LiNO 3 , Bi­(NO 3 ) 3 ·5H 2 O, and Fe­(NO 3 ) 3 ·9H 2 O were dissolved thoroughly in deionized water under vigorous stirring. Few drops of diluted nitric acid were also added into the solution for better dissolution.…”

“…20−22 Bismuth-based oxides display high oxygen ionic mobility as well and have some unique discharge activities during the electrochemical cycling process. 23 This unique characteristic of oxygen mobility, makes bismuth oxides excellent model compounds for mechanistic investigation due to the significant role of oxygen during the electrochemical cycling process.…”

“…Bismuth ions, which usually have a valence state of +3, in some cases, even have oxidation states of +4 or +5, contributing to a larger discharge capacity during the electrochemical cycling process, − due to the larger electron transfer when they are reduced to the metallic state. − Bismuth-based oxides display high oxygen ionic mobility as well and have some unique discharge activities during the electrochemical cycling process . This unique characteristic of oxygen mobility, makes bismuth oxides excellent model compounds for mechanistic investigation due to the significant role of oxygen during the electrochemical cycling process.…”

Controllable Synthesis of Bi2Fe4O9Nanocrystal with High Active Facets and the Enhanced Visible Light Photoelectrochemical Property

“…However, it has recently gained importance as a material for electronic, field-emission, electrochemical, sensors, and lithium ion battery devices [1][2][3] In this paper, Bi 2 Fe 4 O 9 nanocrystals have been controllably synthesized via a chemical co-precipitation process followed by a hydrothermal synthesis through tuning the synthesis microenvironment. They exhibit high performance of photo-to-current conversion under visible-light.…”