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.