  The diffusion of Li in electrode materials is key factor to
charging/discharging rate capacity of Li-ion battery (LIB). Recently,
two-dimensional phosphorene has been proposed as a very promising electrode
material due to its ultrafast and directional lithium diffusion, as well as
large energy capacity. Here, on the basis of density functional theory, we
report that the intrinsic point defects, including vacancy and stone-wales
defects, will block the directional ultrafast diffusion of lithium in
phosphorene. On the defect-free phosphorene, diffusion of Li along the zigzag
lattice direction is 1.6 billion times faster than along the armchair lattice
direction, and 260 times faster than that in graphite. By introducing intrinsic
vacancy and stone-wales defect, the diffusion energy barrier of Li along zigzag
lattice direction increases sharply to the range of 0.17 ~ 0.49 eV, which block
the ultrafast migration of lithium along the zigzag lattice direction.
Meanwhile, the open circuit voltage increases with the emergence of defects,
which is not suitable for anode materials. In addition, the formation energies
of defects in phosphorene are much lower than those in graphene and silicene
sheet, therefore, it is highly demanded to generate defect-free phosphorene for
LIB applications.
