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Báo cáo hóa học: " Copper nanofiber-networked cobalt oxide composites for high performance Li-ion batteries"

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: Copper nanofiber-networked cobalt oxide composites for high performance Li-ion batteries | Nam et al. Nanoscale Research Letters 2011 6 292 http www.nanoscalereslett.eom content 6 1 292 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Copper nanofiber-networked cobalt oxide composites for high performance Li-ion batteries Sang Hoon Nam 1 Yong Seok Kim1 Hee-Sang Shim2 Jong Guk Kim1 and Won Bae Kim1 2 Abstract We prepared a composite electrode structure consisting of copper nanofiber-networked cobalt oxide CuNFs@CoOx . The copper nanofibers CuNFs were fabricated on a substrate with formation of a network structure which may have potential for improving electron percolation and retarding film deformation during the discharging charging process over the electroactive cobalt oxide. Compared to bare CoOxthin-film CoOxTF electrodes the CuNFs@CoOxelectrodes exhibited a significant enhancement of rate performance by at least six-fold at an input current density of 3C-rate. Such enhanced Li-ion storage performance may be associated with modified electrode structure at the nanoscale improved charge transfer and facile stress relaxation from the embedded CuNF network. Consequently the CuNFs@CoOxcomposite structure demonstrated here can be used as a promising high-performance electrode for Li-ion batteries. Introduction Cobalt oxide CoOx is a high-capacity electrode material for Li-ion batteries with a theoretical capacity of at least two times greater than that of graphite ca. 370 mAh g-1 1 . However the cobalt oxides show large irreversible capacity and poor cycling performance caused by Li-alloying agglomeration or growth of passivation layers 1 . In addition severe volume expansion during discharge charge process accelerates fading of the capacity and electrical contact between the electrode material and current collector eventually fails. To overcome these problems several strategies that employ a secondary material 2 a chemically or physically prepared surface coating 3 size optimization 4 5 and fabrication of a nanostructure 6 have