Si thin platelets as high-capacity negative electrode for Li-ion batteries

Pure Si platelets and Ni or Cu layer-laminated Si platelets with difference thickness were prepared, and their charge/discharge properties were examined in 1 M LiClO4/EC + DEC (1:1 by volume) as alternative negative electrode materials to graphite for Li-ion batteries. The shape of thin platelets and lamination with Ni layer are significantly effective to improve the cycleability in Li–Si alloy system by relieving the stress during the alloying/de-alloying processes, reinforcing the mechanical strength and reducing the Li+ ion diffusion length. Moreover, the first irreversible capacity is minimized by reduction of the amount of Ketjen Black (KB) in the composite electrode because of electrolyte decomposition on the surface of KB. Consequently, the Si/Ni/Si-LP30 (30/30/30 nm) composite electrode with 5 wt% KB also exhibits over 700 mAh g−1 even after 50 cycles in 1 M LiPF6/EC + DEC (1:1).