Effects of Impurities on the Electrochemical Properties of LiCoO2

undergoes two successive phase transitions near , which are clearly seen in the voltage profile, when Li is intercalated or deintercalated. The temperature dependence of these phase transitions determines a phase diagram. The phase transitions are very sensitive to impurity levels and can be used as a quality control check on the material. These transitions are also an indicator of composition and absolute cathode potential ( vs. Li metal) in Li ion cells which have no fixed voltage reference.