Reactivety of Carbonaceous Anodes Used in Lithium-ion Batteries, PartI: COrrelation of Structural arameters andReactivity

摘要

Carbonaceous anodes are the most practical electrode for application in lithium-ion battery, mainly due to their low cost, flexibility for modification to achieve high energy capacity and high rate capability ,abundance and environmentally uniquencess. Despite superior advantages of carbonaceous anodes vs other alternative anode and metallic lithium, these is considerable reactivity oflithiated graphite with organic electrolytes, which is a major safety concern. In this work, we report thenature ofgaceous species generated on various carbonaceous anodes during initial charge-dischearge cycling. The correlation between structural parameters of carbonaceous materials and their irreversible capacity loss have been investigted. Structural parameters have been studied using x-ray diffraction, Raman spectroscopy, and scanning and transmission electron microscopy. We have found a direct correlation between crystal morphology, degree ofdisorder, degree of graphitisation and the irreversible capacity loss. There is also a direct correlation between the irrversible capacity loss and the volume of gas generated during initial charge-disharge cycling. Results also show the importance of removing adsorbed and trapped gases in addition to removeal of bonded impurities, such as functional groups from carbonaceus electrode before fabrication of batteries. Particular attention is given on thermal anlaysis for different graphite ocmpuunds and the influence of different parameters and conditions: nature of graphite in term of specific surface area, degree of gaphitization and the length of microcristallites, degree of intercalation, nature of electrolytes on irreversible capacity loss and volume of gases generated during the initial charge-discharge cycles.