Li-ion batteries are an essential source of energy storage for decarbonising our energy use. The gradual introduction of silicon-based compounds into the negative electrode – traditionally made of graphite – appears to be the preferred route to increasing the technology’s energy density to between 300 and 350 Wh/kg. Silicon has a specific capacity of 3,580 mAh/g, which is almost ten times that of graphite. However, this enormous capacity is associated with a 280% volume expansion of the material, compared with just 10% for graphite during intercalation.
At the Li-ion cell level, this ‘breathing’ phenomenon occurs and must be managed. In particular, when a rigid cell is charged, the ‘breathing’ of the active materials expels the electrolyte from the electrochemical core. A lithium salt gradient may develop in the electrode plane in the electrolyte.
This thesis aims to gain a better understanding of this phenomenon by reproducing it experimentally in a specific cell, to establish measurements of lithium salt concentration, and to simulate the phenomenon in a P4D model based on an existing P2D model.
During his PhD, the candidate will develop a wide range of skills and know-how, in a unique combination.