The Cu-Li-Sn Phase Diagram: Isopleths, Liquidus Projection and Reaction Scheme

Abstract

The Cu-Li-Sn phase diagram was constructed based on XRD and DTA data of 60 different alloy compositions. Eight ternary phases and 14 binary solid phases form 44 invariant ternary reactions, which are illustrated by a Scheil-Schulz reaction scheme and a liquidus projection. Phase equilibria as a function of concentration and temperature are shown along nine isopleths. This report together with an earlier publication of our group provides for the first time comprehensive investigations of phase equilibria and respective phase diagrams. Most of the phase equilibria could be established based on our experimental results. Only in the Li-rich part where many binary and ternary compounds are present estimations had to be done which are all indicated by dashed lines. A stable ternary miscibility gap could be found which was predicted by modelling the liquid ternary phase in a recent work. The phase diagrams are a crucial input for material databases and thermodynamic optimizations regarding new anode materials for high-power Li-ion batteries.

Elucidating Lithium Alloying-Induced Degradation Evolution in High-Capacity Electrodes

“…Despite the large amount of work around the Cu 6 Sn 5 composite as an anode electrode, there is no full consensus on the intermediate reactions that occur during the lithiation and delithiation processes. Formation of different possible stoichiometries for Li–Cu–Sn and Li–Sn alloys makes it difficult to establish the intermediate reactions . In general terms, the electrochemical reactions for the Cu 6 Sn 5 composite depend on the state of charge as described in eqs and . The α x , β x , and γ x , y coefficients depend on the lithium content and the alloys (e.g., Li 7 Sn 2 , Li 17 Sn 4 , Li 22 Sn 5 , ...) present in the reaction.…”

“…Formation of different possible stoichiometries for Li−Cu−Sn and Li−Sn alloys makes it difficult to establish the intermediate reactions. 21 In general terms, the electrochemical reactions 19 for the Cu 6 Sn 5 composite depend on the state of charge as described in eqs 1 and 2. The α x , β x , and γ x,y coefficients depend on the lithium content and the alloys (e.g., Li 7 Sn 2 , Li 17 Sn 4 , Li 22 Sn 5 , ...) present in the reaction.…”