Lithium Isotope Effects Accompanying Electrochemical Insertion of Lithium into Metal Oxides

Abstract

ÃÃLithium was electrochemically inserted into SnO 2 and Fe 2 O 3 -SiO 2 binary oxide from the mixed solution of ethylene carbonate and methyl ethyl carbonate containing 1 M LiClO 4 , and the lithium isotope effect accompanying the insertion was investigated. Tin(IV) oxide showed a slight selectivity towards the heavier isotope of lithium with the separation factor (S) ranging from 0.982 to 0.999 at 25 C. Fe 2 O 3 -SiO 2 binary oxide, on the other hand, showed no specific lithium isotope selectivity with S scattered around unity at the same temperature. These results were reasonably understood by assuming the reduction of the metals in the host materials from Sn(IV) to Sn(0) and from Fe(III) to Fe(II) and the formation of lithium oxide upon Li insertion.

Observation of Lithium Isotope Effects Accompanying Electrochemical Release from Lithium Cobalt Oxide

“…This equilibrium isotope exchange reaction, which can also be regarded as an electron exchange reaction, is different from (4) in that both lithium atoms and lithium ions are in the LiCoO 2 phase in (5). The equilibrium constant, K 5 , of (5) larger than unity means that 7 Li is more apt to be oxidized.…”

“…In place of graphite, we previously investigated tin [1], tin oxide [4], tin sulfide [7], iron-silicon composite oxide [4], gallium [5], and zinc [6] as anode material and measured magnitudes of lithium isotope effects by charge reactions. Like graphite, tin, gallium, zinc, and zinc sulfide preferred 6 Li over 7 Li.…”

Preliminary studies of in-cell electrophoresis as 6Li enrichment technique

“…Hg amalgamation was investigated and applied in the past as large scale enrichment method [31][32][33][34][35]. In this way large scale isotope separation for this element took place in the Y-12 Plant in Oak Ridge National Laboratory (ORNL) between 1950 and 1963.…”

“…Alternative non-or less toxic substances can be used as electrodes in this redox reaction. Materials like Sn, SnO 2 and S 2 Sn [31], graphite, Ga [32], Fe 2 O 3 -SiO 2 [33], Zn [34] and PP carbonate [36] on Ni electrodes have been investigated. The reported experimental results show how Sn, Ga, graphite and PC/Ni preferentially take up 6 Li, while metal oxides are slightly 7 Li specific.…”

Chitosan-graft-benzo-15-crown-5-ether/PVA Blend Membrane with Sponge-Like Pores for Lithium Isotope Adsorptive Separation

“…In the recent decades, many other techniques have been developed to separate the lithium isotope, such as electromigration, , laser, , electrochemical, , solvent extraction, − chromatography, , and membrane separation . Among them, solvent extraction and chromatography using crown ether as an extracting agent have been proven to be effective techniques for lithium isotope separation.…”