Lithium disilicate as an alternative silicate battery material. A theoretical study

Advanced atomistic simulations are used to study the ion transport in the Na-and K-doped lithium disilicate Li2Si2O5 which is considered as a potential battery material for solid state alkali batteries. In order to evaluate the ease with which Li2Si2O5 can store Na and K ions, the Na and K incorporation mechanisms into Li2Si2O5 are studied by using lattice statics simulations. Our calculations revealed that the defect formation energies for K and Na doping of Li2Si2O5 amount to 0.49 eV/dopant and 0.96 eV/dopant, respectively. The Li ion diffusion in Li2Si2O5 is significantly enhanced upon Na and K doping. The activation energies of Li ion diffusion in all samples are in the range of 0.5-0.6 eV, while for conduction 0.4-0.5 eV. At higher dopant concentrations, K doping increases the Li ion diffusion/ conduction, reaching their improved transport properties at x = 0.14 with low activation energy for diffusion and conduction. At a low dopant concentration of x = 0.02, Na doping also improves the Li ion diffusion/conduction. Our results demonstrate the potential of the doped lithoum disilicate Li2Si2O5 as an effective material for alkali ion batteries and strongly suggest experimental verification.

Automated summary

Advanced atomistic simulations were used to study ion transport in the Na- and K-doped lithium disilicate Li2Si2O5. The results showed that Na and K doping significantly enhanced Li ion diffusion and conduction in the material.