Abstract:
Layered Li9V3(P2O7)3(PO4)2 has attracted considerable interest as a novel cathode material for potential
use in rechargeable lithium batteries. The defect chemistry, doping behavior and lithium difusion
paths in Li9V3(P2O7)3(PO4)2 are investigated using atomistic scale simulations. Here we show that the
activation energy for Li migration via the vacancy mechanism is 0.72eV along the c-axis. Additionally,
the most favourable intrinsic defect type is Li Frenkel (0.44eV/defect) ensuring the formation of Li
vacancies that are required for Li difusion via the vacancy mechanism. The only other intrinsic defect
mechanism that is close in energy is the formation of anti-site defect, in which Li and V ions exchange
their positions (1.02eV/defect) and this can play a role at higher temperatures. Considering the solution
of tetravalent dopants it is calculated that they require considerable solution energies, however, the
solution of GeO2 will reduce the activation energy of migration to 0.66eV
