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

摘要

Lithium-ion batteries (LIBs) show poor performance at temperatures below0 ℃ due to sluggish reaction kinetics, hindered diffusion, and electrolytefreezing. Materials that alloy with lithium offer higher specific capacity thangraphite anodes and are studied extensively at room temperature, but theirlow-temperature behavior is not well understood. Here, the electrochemicaland transformation behavior of three alloy materials (antimony, silicon, andtin) are investigated. It is shown that antimony is particularly well suited forlow-temperature applications due to its relatively high electrode potentialand promising electrochemical stability at low temperatures. It is found thatlithium-antimony alloys can be cycled down to ?40 ℃ with ten times higherspecific capacity than graphite on the first cycle. The galvanostatic intermittenttitration technique is used to understand the kinetic and thermodynamiclimitations of these electrode materials at low temperatures, and X-ray diffractionshows that electrochemical phase transformation behavior is also alteredat low temperatures. Finally, it is found that the use of reference electrodes isnecessary at low temperatures to avoid counter electrode effects. This investigativestudy provides new understanding of the behavior of alloy anodes atlow temperatures and reveals the need for electrode/electrolyte optimizationto enable low-temperature LIBs.