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Long-Life Silicon/Graphite Anode with Nano Carbon Coatings for Lithium Ion Battery - Graphene Nanowalls and Nitrogen Incorporated Ultrananocrystalline Diamond

Monday, 20 June 2016
Riverside Center (Hyatt Regency)
Y. Tzeng and Y. T. Pan (National Cheng Kung University)
Although lithium ion batteries (LIBs) have been used in many consumer  and industrial products, the energy storage capacity per volume/weight and the battery cycling lifetime have much room for further improvement.  This is especially challenging for high demanding applications such as long-range electric vehicles, and smart grid renewable energy storage. Among LIB anode materials,  graphite is the most common one in the market today. Many novel anode materials have been studied in pursuit of much higher battery energy storage capacity for a given volume and weight. Among them, silicon is the most attractive one which theoretically is capable of storing more than ten times of energy than that of graphite anode for the same anode weight. However, silicon suffers from extensive volume expansion and shrinkage by about 400% when it cycles through fully charged and discharged states. The volume difference leads to breakage of silicon particles and the loss of their electrical contacts to the current collector and thus its capability of further discharging and charging. On the other hand, graphite has a layered structure, which suffers from breakage between adjacent layers into smaller pieces and thus possibly loses the capability of broken apart small graphite pieces in charging and discharging. Therefore, technologies for preventing aforementioned huddles against achieving long-life and high-capacity LIBs are highly desirable. Novel electrically conductive ultrananocrystalline diamond, graphene nanowalls, and diamond-graphene hybrid nano-carbon coatings have been applied by plasma enhanced chemical vapor deposition technique to graphite and silicon based LIB anodes and achieved much longer cycling lifetime compared to those without such nano carbon coatings. This paper will present the nano-carbon coating processes, materials characterization, LIB fabrication processes, and the characterization of LIB half cells which demonstrates enhance lifetime and charge storage capacity.