Safety aspects of graphite negative electrode materials for lithium-ion batteries

Safety aspects of different graphite negative electrode materials for lithium-ion batteries have been investigated using differential scanning calorimetry. Heat evolution was measured for different types of graphitic carbon between 30 and 300degreesC. This heat evolution, which is irreversible, starts above 100degreesC. From the values of energy evolved, the temperature rise in complete lithium-ion cells was estimated. The heat evolved between 80 and 220degreesC is a linear function of the irreversible charge capacity of the carbon. The specific Brunauer, Emmett, and Teller method surface area measured by nitrogen gas adsorption, which is usually also a linear function of irreversible charge capacity, may be used with certain reservations to calculate approximately the heat evolution of graphitic carbon negative electrode materials in lithium-ion batteries. Graphite materials are usually safer if their irreversible charge capacity during the first cycle is low. (C) 2002 The Electrochemical Society.