Modeling of solid-state lithium-oxygen battery with porous Li1.3Al0.3Ti1.7(PO4)3-based cathode

Solid-state lithium-oxygen batteries have attracted great attention due to their high theoretical energy density, excellent safety, and cycle stability. The present study establishes a new, highly efficient mathematical model for a solid-state lithium-oxygen battery, which utilizes a porous Li1.3Al0.3Ti1.7(PO4)(3) (LATP) solid electrolyte sheet as the cathode. The study includes and considers the transport of lithium ions and oxygen molecules, the kinetic equation of electrochemical reaction, and the charge conservation equation. The active surface area of the cathode is calculated by the binary particle mixed percolation theory, and a product growth model is proposed to describe the active surface's evolution. Validated by experimental data, the model can predict both the voltage specific capacity curves under different currents and the electrode behavior of discharge. The results show that the initial cathode active surface area and battery capacity are sensitive to such factors as LATP particle radius, LATP volume fraction, and carbon particle radius. It is concluded that the discharge product in solid-state lithium-oxygen battery has more uniformly distributed, which aids in oxygen diffusion and a longer discharge process.