We have carried out extensive ultra-slow scan cyclic voltammetry on nanoscale silicon to elucidate the electrochemical formation of Li-Si alloys and determine diffusion coefficients. Our results suggest a multi-cycle permanent conversion of bare silicon to the first Li-Si phase, Li₁₂Si₇, as the least lithiated state. This constitutes a significant part of the capacity fade observed in silicon electrodes. In addition we observe multiple diffusion constants in long-term current transients using established models from literature.  The electrochemically obtained data will be complemented by a neutron based technique previously developed in our group, referred to as neutron depth profiling, to elucidate the Li distribution and potential trapping or slow kinetics of Li₁₂Si₇ within the material resulting in capacity fade.