Na- and K-Doped Li2SiO3 as an Alternative Solid Electrolyte for Solid-State Lithium Batteries

The search for high-performance solid electrolyte materials with the potential to increase the safety and energy density of next-generation Li-ion batteries is becoming ever more important for the electrification of transport and grid-scale energy storage. In this study, molecular dynamics simulations are used to study ion transport in Na- and K-doped Li2SiO3 as a potential material for future solid-state lithium batteries. Lattice statics calculations are also used to determine the defect energetics of this system, which reveal the ease with which Li2SiO3 can store Na and K. Our calculations reveal low defect formation energies of 0.07 and 1.95 eV for Na and K doping of Li2SiO3, respectively. Room-temperature Li-ion diffusion in Li2SiO3 is significantly enhanced by the inclusion of a low concentration of Na (1 mol %) with a notably low activation energy of 0.34 eV, compared with 0.48 eV for the undoped system. Alternatively, at higher dopant concentrations in excess of 3 mol %, it is K doping that results in an enhancement in Li-ion diffusion rather than Na doping. Our results highlight the potential of doped Li2SiO3 as a solid electrolyte material for Li-ion batteries and encourage further experimental verification of these promising findings.