In situ ¹¹⁹Sn Mössbauer Effect Study of Li−CoSn₂ Electrochemical System

Abstract

Crystalline CoSn2 powders prepared by a ceramic route under an Ar/H2 controlled atmosphere are examined as a negative electrode for lithium-ion batteries. Ex situ X-ray diffraction measurements show that an electrochemically driven solid-state transformation of CoSn2 occurs during the first reaction period. The complete reaction mechanism of CoSn2 is investigated by in situ 119Sn Mössbauer spectroscopy using a Li-ion plastic cell. The conversion reaction proceeds through a biphasic system, with CoSn2 direct transformation into both a lithium-rich Li y Sn (where y ≈ 3.5) compound and metallic Co nanoparticles. On charge, the electrochemical process is more complex and it includes the conversion of the Li y Sn compound into a modified CoSn2 nanocompound with a variable composition, i.e., a Li y Co z Sn2 matrix, which is the active species for the following cycles.

Chemical Bonding in Compounds of the CuAl2 Family: MnSn2, FeSn2 and CoSn2

“…The suggested applications range from data storage [6] and sensors [6] to electrodes in rechargeable batteries. [7][8][9][10][11] . In addition, FeSn 2 plays a role as mediating layer in the tinning process.…”

Lithium insertion–deinsertion mechanism in NbSn2 anode studied by 119Sn Mössbauer spectroscopy

“…It is now well-established that Sn-and transition-metal-based alloys react toward lithium through conversion reactions leading to high specific capacities, as shown with MnSn 2 [3], FeSn 2 [4], CoSn 2 [5], Ni 3 Sn 4 [6] and Cu 6 Sn 5 [7]. The transition metal, an inactive component, is extruded from the pristine unit cell whereas Sn reacts with lithium to form a Li-rich Li x Sn alloy.…”

119Sn Mössbauer spectroscopy: a powerful tool to unfold the reaction mechanism in advanced electrodes for lithium-ion batteries

“…To the best of our knowledge, stable ternary Li-CoSn phases have not been reported. However, several authors have assumed the occurrence of unknown Li-Co-Sn phases in the electrodes [1][2][3]. Further studies are needed to explore this feature.…”

“…Intermetallic materials are envisaged as a promising alternative to carbon materials for the negative electrode in lithium ion batteries [1][2][3]. These intermetallic materials can be formed by Li-alloying elements and by Li-non-alloying elements, and their crystallinity and particle size are relevant properties that influence on the electrochemical behavior.…”