Defects, dopants and Li-ion diffusion in Li2SiO3

Abstract

Lithium metasilicate, Li2SiO3, attracts considerable interest for the development of solid breeding blanket material in fusion reactors and solid electrolyte material in lithium ion batteries. Atomistic simulations are employed to study defect processes, dopant behaviour and lithium ion migration in Li2SiO3. The vacancy assisted long range Li is along the bc plane with the lower activation energy of 0.21 eV suggesting that high ionic conductivity would be observed in this material. The most thermodynamically favourable intrinsic defect type is Li Frenkel (1.66 eV/defect) suggesting that this defect process will ensure the formation of Li vacancies required for Li ion diffusion. Subvalent doping by Al3+ on Si site can increase the Li content in Li2SiO3, however, experimental verification is required. The favourable isovalent dopant on the Si site is calculated to be Ge4+.