Si nanoparticles encapsulated in CNTs arrays with tubular sandwich structure for high performance Li ion battery

Silicon has been widely researched as next-generation lithium-ion batteries (LIBs) anodes on account of its high energy density . To solve the large volume expansion and low electroconductivity , carbon coating Si strategies have been developed and shown some progress. In this study, Si nanoparticles were injected into the inner of the double-deck carbon nanotubes for the formation of a sandwich-like structure to enhance the electrochemical properties of Si electrodes. Thereinto, carbon nanotube arrays (CNTs) were fabricated by liquid paraffin as the carbon resource instead of unsaturated hydrocarbon for the first time by chemical vapor deposition (CVD) method. Due to the advantage of the specific structure designed, the as-prepared material shows superior rate performance and excellent cycling stability with high capacity retention (1310 mAh g −1 at 0.1 A g −1 after 100 cycles and 1050 mAh g −1 at 1 A g −1 after 500 cycles with 98% of Coulombic efficiency). Furthermore, the full cell was also assembled with LiFePO 4 as the cathode and manifested a high energy density of 374 Whkg −1 with stable cycling performances (92% capacity retention ratio after 200 cycles).