Investigation of structural change and electrochemical reaction of spinel-LiMn₂O₄ by neutron diffraction

The structural change during electrochemical cycling in full-cell system has been investigated by neutron diffraction method and the full-cell consists of spinel-lithium manganese oxide cathode and graphite anode. The structural variation has been monitored by in-situ neutron diffraction technique at different state of charges (SOCs), and the obtained data were compared with ex-situ powder neutron diffraction patterns. Phase transitions for lithiated/delithiated graphite can clearly explain that the intercalated lithium ions in graphite are not perfectly extracted during a delithiaion process. The content of LiC₁₂ phase increases as an increase in electrochemical cycle numbers, and the lattice parameter of LiMn₂O₄ also decreases due to the reduction of the amounts of Li ions, which can be reversibly intercalated/deintercalated into/from the structure.