In operando neutron diffraction study of a commercial graphite/(Ni, Mn, Co) oxide-based multi-component lithium ion battery

Abstract In situ neutron diffraction was employed to investigate the structural evolution of the electrode materials in an ICR 10440 commercial cylindrical lithium-ion battery, which has a discharge capacity of 360 mAh and a nominal voltage of 3.7 V. A three-phase mixture of Li(Ni,Mn,Co)O 2 , LiCoO 2 and LiMn 2 O 4 was identified as the active material of the cathode, with graphite acting as the anode material. The study revealed that the graphite anode underwent structural changes to form a series of insertion-type lithiated derivatives, with up to 12.7% volume expansion for the Li-saturated compound LiC 6 . The charge-discharge behavior was more complex for the cathode. Here, the charge process was associated with partial lithium depletion from the initially Li-saturated compounds, leading to volume shrinkage for Li(Ni,Mn,Co)O 2 , in contrast to (Ni,Mn)-free LiCoO 2 . Electrochemical discharge experiments performed under a fast regime (2 C) at 5, 25 and 45 °C revealed that the discharge capacity followed the trend of an increased diffusion rate of Li + ions in the electrolyte and Li atoms in both electrodes, being highest for 45 °C. At the lowest tested temperature (5 °C), a rapid drop in the discharge capacity took place using the same kinetic regime.