Magnetic phase transition of Li0.75CoO2 compared with LiCoO2 and Li0.5CoO2

摘要

Magnetic and thermodynamic properties of the LiCoO2 positive-electrode material used in lithium-ion battery were first examined. Partially deintercalated LiCoO2 that is Li0.75CoO2, showed definite anomaly in the magnetic susceptibility at T=ca. 175 K probably related to magnetic phase transition which was supported by observation of a weak anomaly in heat capacity. On the other hand, LiCoO2 did not show such magnetic phase transition as expected, whereas Li0.5CoO2 a weak one in the similar temperature range. These behaviors are discussed in association with the mixing of Co 3+ and Co 4+ electronic structures.