Low Temperature Preparation and Electrochemical Properties of LiFeSi2O6

Wednesday, 27 May 2015: 08:40
Buckingham (Hilton Chicago)
S. Zhou (University of Southern California), G. King (Los Alamos National Laboratory), D. Scanlon (University College London, Diamond Light Source Ltd.), M. T. Sougrati (CNRS-Universite Montpellier 2), and B. Melot (University of Southern California)
The growing demand for Li-ion batteries requires the development of inexpensive materials that can be made in a sustainable fashion. Here we report a new low-temperature preparation for and the first electrochemical characterization of LiFeSi2O6, a hugely Earth-abundant, rock-forming mineral. We have found that LiFeSi2O6 undergoes a reversible electrochemical reaction against Li centered around 2 V with capacities near 60% of the theoretical maximum.
However, an extremely slow rate of cycling (C/200) or small particle size of LiFeSi2Ois required to obtain a reasonable capacity, which indicates that Li+-(de)insertion in LiFeSi2O6 is kinetically hindered. To understand the origin of this kinetic hindering, we conducted Ritveld refinement of the atomic displacement parameters of LiFeSi2O6 against the neutron diffraction data obtained from the HIPD beamline at Los Alamos National Laboratory. The results not only allowed us to clarify the preferred diffusion pathway for Li+ ions in LiFeSi2O6, but also enabled us to link the kinetic hindering in the material to its structural rigidity, which is indicated by the flat-shaped atomic displacement sphere of oxygen atoms along the polyhedra linkages in the LiFeSi2O6 structure.