Tham khảo tài liệu 'lithium-ion batteries part 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Towards high performance anodes with fast charge discharge rate for LIB based electrical vehicles 21 Fig. 18. Cycle performance a and Coulomb efficiency b of an array of 1D TiC 2 electrode at current densities of 10 and 30 A g. Fang et al. 2009 The 2D nanostructured anodes viz. of sheet or thin-film type have drawn much attention with an expectation of increasing surface area. However this type of structure exhibited poor anodic performance at high C D rate. In some cases 2D nanosheet structure was used as a platform to introduce 3D porous structure. Tang et al. 2008 In the case of 3D porous structure it is very important to introduce a continuous phase of porosity for effective ionic pathways to the surface of the active material. Most of 3D porous structures with continuous pore phase can be prepared via chemical reactions including sol-gel reaction CVD and electrodeposition which are conducted under controlled conditions. When combined with template techniques such as porous membranes colloidal crystals micelles and etc. these chemical reactions allow the formation of hierarchical network structure with size-controlled continuous pore phase. Long et al. 2004 Yu et al. 2007 recently reported that Li2C-CuC-SnC2 composites with porous spherical multideck-cage morphology show the specific capacity of 800 mAh g over at 1C C D rate see Figure 19 . Fig. 19. SEM micrographs of as-deposited Li2C-CuC-SnC2 a and cycle performance results at various C D rates b . Hu et al. 2007 22 Next generation lithium ion batteries for electrical vehicles Surface modification of the active materials Positive charge transfer property of the surface of the active material is another essential factor to enhance the ionic transportation. High rate positive charge Li ions transfer can be achieved by increasing mass transfer coefficient which varies with the morphologies of the anode materials. To modify the surface of the active material doping and or encapsulation methods are widely .
