Role of a Topotactic Electrochemical Reaction in a Perovskite‐Type Anode for Lithium‐Ion Batteries

Abstract

One of the mechanisms for some transition‐metal oxides as anodes of a lithium‐ion battery (LIB) is their conversion into variable‐valence oxides or even metals. The conversion reaction involves oxide‐ion transport and the formation/decomposition of Li2O, but very limited research has been done on the oxide‐ion transport of the anodes. Perovskite‐type oxides containing transition elements show high tolerance to oxygen‐deficiency and high oxide‐ion conductivity, which could benefit the oxide‐ion transport and structural stability. In this study, a CaMnO3‐based perovskite involving little volumetric variation upon oxygen uptake/release is examined to study the intermediate oxygen‐deficient product, and the loss of oxygen is found to follow the route of a topotactic electrochemical reaction. In particular, the conversion reaction of the perovskite involves the formation of oxygen‐deficient perovskite and rocksalt‐type CaMnO2 depending on the grain size.

Enhanced Water Splitting Electrocatalysis over MnCo2O4 via Introduction of Suitable Ce Content

“…The equivalent circuit of Nyquist plots is composed of solution resistance ( R s ), related to the double layer capacitance (CPE), charge transfer resistance ( R ct ) and Warburg impedance (Ws). The lower value of R ct value means the faster electrochemical reaction rate, which can be observed from the diameter of semicircles. − It is obvious that Ce-MnCo 2 O 4 -3% reveals the lowest charge transfer resistance value ( R ct ), suggesting that the introduction of Ce with suitable content would lead to much higher charge-transfer kinetics due to the rich redox properties and enhanced surface activity, which is highly accordant with its lowest Tafel slope and overpotential. In addition, the low frequency straight line can be ascribed to the response from the constricted diffusion of OH – within nanopores of nanostructured electrocatalysts .…”

A B-site doped perovskite ferrate as an efficient anode of a solid oxide fuel cell with in situ metal exsolution

“…A dense La0.9Sr0.1Ga0.8Mg0.2O2.85 (LSGM) electrolyte was prepared via the pressing of a commercial powder and calcination at 1500 o C for 5 hours 28 . La0.8Sr0.2CoO3 (LSC) powder for the cathode was synthesised via the combustion method 28,29 where the precursors of La(NO3)3.9H2O (Macklin, 99%), SrCO3 (Aladdin, 99.5%), Co(NO3)2.6H2O (Macklin, 99%) and citrate acid (1:1 to the cation in molar ratio) as complexing agent were dissolved in diluted HNO3 to obtained a clear solution, which was then dried at 80 o C on a hotplate. After the evaporation of water, the gel was ignited at 350 o C and the ashes were collected and calcined at 900 o C to obtain powder particles of sizes in nanometres.…”

An Anode Material for Lithium‐Ion Batteries Based on Oxygen‐Deficient Perovskite Sr2Fe2O6−δ

“…Tin‐based materials (its alloys and oxides) as well as various oxides of transition metals have been investigated for anode application in order to substitute graphite. The tin‐based materials have been reported to have high capacity for anode application, where the cycles of charge/discharge involve reversible formation and decomposition of Li−Sn alloy, resulting in high capacity . The transition metal oxides often do not intercalate or form alloys .…”

“…The tin-based materials have been reported to have high capacity for anode application, where the cycles of charge/discharge involve reversible formation and decomposition of LiÀ Sn alloy, resulting in high capacity. [5,7,11,13,14] The transition metal oxides often do not intercalate or form alloys. [7] The reversible capacity in transition metal oxides is believed to develop from the reversible change in oxidation state of the metal and formation/ decomposition of lithium oxide.…”

“…[7,[16][17][18] Oxide materials with different structures, such as spinel and perovskite phases, have been studied as alternative anodes. [3,8a-b] For some perovskite oxides the role of topotactic electrochemical reaction, [11] or other parameters, such as the addition of rare earth metals have been studied. [12] The reversible capacity in spinel type materials such as ZnCo 2 O 4 has been observed and is believed to arise from intercalation of lithium into spinel and decomposition of the structure, followed by formation of metal particles and alloying with zinc.…”