Temperature induced compositional redistribution in blended insertion electrodes

Blending insertion compounds is a novel and promising approach to design advanced electrodes for future lithium-ion batteries. In spite of the considerable improvements regarding safety issues and power density, the understanding of basic interactions between the constituents of the blend and differences towards common single compound insertion electrodes is still ongoing. Herein we explore and verify the effect of temperature induced compositional redistribution of lithium-ions between the constituents of a blended insertion electrode for the first time. A model-like blend electrode and a special experimental setup is used to measure the compositional redistribution current between the constituents when subjected to a temperature change. The amount of lithium exchanged between the constituents of the blend is also derived theoretically based on the thermodynamic properties of the pure constituents, showing excellent agreement to the experimental results. Theoretical and experimental results proof that significant amounts of lithium are exchanged between the constituents without any cycling of the battery, suggesting that this effect may intrinsically reduce the cycle life of batteries with blended insertion electrodes.