Heat Capacities of LiCu2O2 and CuO in the Temperature Range 323-773 K and Cu2O in the Temperature Range 973-1273 K

The Li-Cu-O system is a promising materials system for the development of new anode materials for lithium ion batteries based on copper oxides. The specific heat capacities of binary and ternary oxides in this system are required to generate thermodynamic descriptions using the CALPHAD method. Additionally, heat capacity data can be used to support development of thermal management systems for the lithium ion batteries based on these materials. In this study, differential scanning calorimetry was used to measure the heat capacities of the binary copper oxides and of the ternary LiCu2O2. The heat capacity of CuO was measured from 323 to 773 K and that of Cu2O was measured from 973 to 1273 K. The heat capacity of CuO is in good agreement with literature data. However, the heat capacity of Cu2O is slightly lower than that calculated using CALPHAD-based thermodynamic descriptions of the Cu-O system but higher than that determined using ab initio calculations. Although the synthesis of single phase LiCu2O2 is difficult because of the mixed oxidation states of Cu, our heat capacity measurements show that the constituent additivity method can be used to estimate the heat capacity of LiCu2O2.