Irreversible dilation of graphite composite anodes influenced by vinylene carbonate

The volumetric expansion of graphite composite electrodes for Li ion battery is investigated by electrochemical dilatometry in electrolytes with different concentration of vinylene carbonate (VC). While the reversible dilation of the anode coatings is not influenced by the VC concentration the irreversible part displays a strong dependence. With the increase of VC amount in the electrolyte the irreversible dilation decreases significantly, showing that the addition of VC has a positive effect on the mechanical performance of the battery. The observed behavior is associated with differences in the decomposition mechanism of the electrolyte components and their reaction kinetics, influenced by the presence of VC. In contrast to the VC containing electrolyte, the passivation layer formed on the anode in the absence of VC cannot effectively terminate the electroactivity of the graphite surface and the electron charge transfer. This leads to a continuous incorporation of decomposition products in the composite layer during the subsequent cycles and related to this additional irreversible volume expansion. The analysis performed by means of combined application of dilatometric, impedance and XPS techniques reveals the positive role of VC for improving the electrochemical-mechanical properties of the graphite porous anode. [Display omitted] •SEI formation can be studied by electrochemical dilatometry.•Vinylene carbonate reduces the irreversible dilation of graphite anode.•Large irreversible dilation is observed in the absence of VC.•SEI formation in presence of VC restricts the ionic transport in the porous anode.•Electrolyte decomposition products incorporate in the anode structure.