Polyaniline induced nano-carbon with multi-doped heteroatoms for high-rate lithium ion battery anodes.

Abstract

Nanostructure design, construction of porous architecture and heteroatom doping are three feasible strategies for advanced lithium ion batteries (LIBs) based on carbon anodes. Here, a unique polyaniline (PANI) @carbon@PANI sandwiched structure has been constructed via simultaneously PANI loading on both the inner and outer surfaces of ultra-wide graphitic carbon nanotubes. The morphology and thickness of PANI coating could be regulated by polymerizing agent of aniline and surface ethanol modification, and N, O and P heteroatoms are efficiently doped in the carbon lattice as extra Li⁺reservoirs through thermal annealing. Particularly, pyrrolic nitrogen and pyridinic nitrogen dopants could result in high-activity sites conducive to Li⁺adsorption, and reduce the diffusion barrier of Li⁺. Therefore, when the multi-doped nano-carbon is utilized as anodes for LIBs, PCPm-excess-600 with expanded interlayer spacing (0.425 nm) could exhibit a specific cycling capacity up to 944.44 mAh/g. And the high doping level of active pyridinic nitrogen contributes a large number of Li⁺adsorption sites to PCPm-600 with multi-level pore structures, and the resulting surface pseudo-capacitance greatly improves its rate capability. After 5000 reversible cycles under a ultra-large rate of 2000 mA/g, its specific capacity is as high as 388.57 mAh/g with capacity retention over 80%, and finally a high-capacity and fast-charging anode material with extremely long service life is obtained, providing new thoughts for the design and synthesis of carbon anodes.