The integration of Na metal anode with a fast conductor solid electrolyte can facilitate the development of high energy density batteries with fast charging capabilities that are safer and more sustainable that the Li counterparts. A challenge to achieve fast charging rates without cell degradation is to promote and homogenous and fast ionic flow across the cell, which requires high Na conductivities in the solid electrolyte (10^-2-10^-3S⋅cm^-1) and stable interfaces with low resistances. In this regard, NaSICON electrolytes have been developed with bulk conductivities of 15 mS⋅cm^-1 facilitating super-fast ion transport, however, the dynamic Na metal/solid-electrolyte interfaces still show high resistances (10²-10³ Ω⋅cm²) and chemical/electrochemical instabilities leading to premature cell degradation. In this work, we prove that the Na/NaSICON interface can be optimised so that the resistance is decreased below 1 Ω⋅cm² allowing to reach current densities of up 10mA⋅cm². We developed operando strategies to reveal the degradation dynamics of the Na/NaSICON interface, proving that the interface can be kinetically stabilised and that the presence of contaminants in the Na metal can play a fundamental role on its electrochemical degradation.