The entropic term is measured using a potentiostatic method which involves measuring the dependency of OCV on temperature (Figure ). The temperature is changed three times at each lithium concentration. This provides four OCVs at the different temperatures; the entropic term can be calculated from the gradient of a line through the points. This process is repeated to map the stoichiometric range of the electrodes. It can take many hours to attain OCV at a particular SOC and temperature, therefore the thermal stability of the electrolyte needs to be considered when choosing the temperature regime. This is because at high temperatures due to electrochemical instability, particularly at the graphite interface, it is more difficult to attain OCV. Choosing a lower temperature regime avoids instabilities, while allowing the thermodynamic behaviour to be measured.