Investigating Mechano-Electrochemical Coupling Phenomenon in Lithium-Ion Pouch Cells Using In-situ Neutron Diffraction

In lithium-ion battery electrode materials, internal mechanical strain is coupled to electrochemical processes. As a result, lithium-ion electrodes can be used for mechano-electrochemical energy harvesting. A promising way to investigate this mechano-electrochemical coupling is through neutron scattering, which can measure the lighter elements that compose battery anodes. In this paper, we conduct in-situ neutron diffraction studies on commercial lithium-ion pouch cells using the VULCAN diffractometer at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. By applying stress on these pouch cells, and examining the phase-specific lattice strains, Bragg peak intensities, and peak broadening, we can gain insight into the mechano-electrochemical correlation in lithium-ion electrodes. We measure a negative electrochemical lattice strain of the graphite electrode, indicating that stress causes lithium ions to leave the graphite structure.