Abstract: The Changes in interface performances of LiMn₂O₄/LiPF₆-(EC+DEC) solution with before
and after charge-discharge cycling and storage were investigated by impedance technique combined with cyclic voltammetry. The resistance and
the capacitance of the surface film increase significantly during the first several cycles, but nearly remain unchanged later. The charge-
transfer resistance increases, but the interface capacitance nearly remains unchanged. The surface film resistance decreases at the early
stage during storage but then increases a little with time. The charge-transfer resistance increases significantly after storage,
especially at the early stage during storage. The surface film capacitance and interface capacitance nearly remain unchanged during
storage. Possible mechanisms for the changes in these interface performances were explained.

Key words: LiMn₂O₄, surface film, charge transfer, impedance spectroscopy