Abstract : Batteries with a lithium metal electrode have high theoretic capacity, high voltage, and permit adaptable and flexible geometries. Their development at an industrial scale is yet compromised by the electrodeposition of irregular lithium aggregates, called dendrites, during recharge. Dendritic growth at low current densities is still poorly understood: it is probably related to an irregular distribution of the local current density due to the inhomogeneities at the lithium/electrolyte interface. This manuscript presents our work on symmetric Li/electrolyte/Li cells that allow studying the lithium deposition and dissolution simultaneously. The electrolyte is either based on PEO+LiTFSI (working at 80°C), or PVdF-HFP/POE soaked in EC:PC+LiTFSI (working at room temperature). We have studied these cells by in situ visualisation of the inter-electrode area, and by spectroscopic impedance. In visualisation cells containing PEO charged with a coloured salt, we have observed the evolution of optical absorption profiles, directly related to the concentration profiles in the electrolyte. In cells containing a gelified electrolyte we have measured local variations of the current density. Our impedance measurements show the presence of two passivation layers evolving differently during ageing. Under galvanostatic polarisation, the potential response shows the presence of a poorly diffusive media at the lithium/electrodes interface.