Polyaniline-induced nanocarbon with multi-doped heteroatoms for high-rate lithium-ion battery anodes

Abstract Nanostructure design, the construction of porous architectures, 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 loading PANI on both the inner and outer surfaces of ultra-wide graphitic carbon nanotubes. The morphology and thickness of the PANI coating can be regulated by a 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. In particular, pyrrolic nitrogen and pyridinic nitrogen dopants can result in high-activity sites conducive to Li+ adsorption and can reduce the diffusion barrier of Li+. Therefore, when the multi-doped nanocarbon is utilized as an anode for LIBs, PANI@carbon@PANI-modified (PCPm)-excess-600 with expanded interlayer spacing (0.425 nm) can exhibit a specific cycling capacity up to 944.44 mAh g−1. The high doping level of active pyridinic nitrogen contributes a large number of Li+ adsorption sites to the PCPm-600 with multi-level pore structures, and the resulting surface pseudo-capacitance greatly improves its rate capability. After 5000 reversible cycles under an ultra-large rate of 2000 mA g−1, its specific capacity is as high as 388.57 mAh g−1 with a capacity retention of over 80%, and finally a high-capacity and fast-charging anode material with an extremely long service life is obtained, providing new thoughts for the design and synthesis of carbon anodes.