A New Null Matrix Electrochemical Cell for Rietveld Refinements of In-Situ or Operando Neutron Powder Diffraction Data

In-situ techniques proved to be exceptionally useful tools to understand electrode materials for Li-ion batteries but in-situ neutron diffraction (ND) during battery operation knew a slow development, due to the intrinsic difficulties it held. We have designed a new electrochemical cell, manufactured with a completely neutron-transparent (Ti,Zr) alloy. Such a cell is able to combine, for the first time, good electrochemical properties and the ability to collect neutron diffraction patterns operando, with good statistics and no other Bragg peaks than those of the electrode material of interest. This allows detailed structural determinations of electrode materials by Rietveld refinement during operation. First case studies hereby reported are the olivine LiFePO4 and the overstoichiometric spinel Li1.1Mn1.9O4, investigated at the D20 diffractometer of ILL (Grenoble), and compared to pure powder patterns obtained from the high-resolution D2B diffractometer. These studies demonstrate the feasibility and reliability of such experiments and open the field to a wide range of investigations on battery electrode materials. (C) 2013 The Electrochemical Society. All rights reserved.