Low-Temperature Behavior of Alloy Anodes for Lithium-Ion Batteries

Lithium-ion batteries (LIBs) show poor performance at temperatures below 0 degrees C due to sluggish reaction kinetics, hindered diffusion, and electrolyte freezing. Materials that alloy with lithium offer higher specific capacity than graphite anodes and are studied extensively at room temperature, but their low-temperature behavior is not well understood. Here, the electrochemical and transformation behavior of three alloy materials (antimony, silicon, and tin) are investigated. It is shown that antimony is particularly well suited for low-temperature applications due to its relatively high electrode potential and promising electrochemical stability at low temperatures. It is found that lithium-antimony alloys can be cycled down to -40 degrees C with ten times higher specific capacity than graphite on the first cycle. The galvanostatic intermittent titration technique is used to understand the kinetic and thermodynamic limitations of these electrode materials at low temperatures, and X-ray diffraction shows that electrochemical phase transformation behavior is also altered at low temperatures. Finally, it is found that the use of reference electrodes is necessary at low temperatures to avoid counter electrode effects. This investigative study provides new understanding of the behavior of alloy anodes at low temperatures and reveals the need for electrode/electrolyte optimization to enable low-temperature LIBs.