tailieunhanh - Báo cáo hóa học: " Lithium ion storage between graphenes"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Lithium ion storage between graphenes | Chan and Hill Nanoscale Research Letters 2011 6 203 http content 6 1 203 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Lithium ion storage between graphenes Yue Chan James M Hill Abstract In this article we investigate the storage of lithium ions between two parallel graphene sheets using the continuous approximation and the 6-12 Lennard-Jones potential. The continuous approximation assumes that the carbon atoms can be replaced by a uniform distribution across the surface of the graphene sheets so that the total interaction potential can be approximated by performing surface integrations. The number of ion layers determines the major storage characteristics of the battery and our results show three distinct ionic configurations namely single double and triple ion forming layers between graphenes. The number densities of lithium ions between the two graphenes are estimated from existing semi-empirical molecular orbital calculations and the graphene sheets giving rise to the triple ion layers admit the largest storage capacity at all temperatures followed by a marginal decrease of storage capacity for the case of double ion layers. These two configurations exceed the maximum theoretical storage capacity of graphite. Further on taking into account the charge-discharge property the double ion layers are the most preferable choice for enhanced lithium storage. Although the single ion layer provides the least charge storage it turns out to be the most stable configuration at all temperatures. One application of the present study is for the design of future high energy density alkali batteries using graphene sheets as anodes for which an analytical formulation might greatly facilitate rapid computational results. Introduction The development of an efficient lithium ion battery which has the highest energy density and the quickest recharge time relies on a complicated optimization of novel materials for the anode the