A new electrochemical cell has been specially designed for operando experiments at synchrotron facilities both for X-ray diffraction and X-ray absorption. It allows the investigation of insertion materials under high current densities (up to 5C rate) and hence to study complex phenomena of structural and electronic changes out of equilibrium. The LiFePO4-FePO4 system has been chosen as a case study to validate this cell, and tricky phenomena, with apparent delays in phase formation compared with the number of electrons exchanged, have been spotted.