Strontium stannate as an alternative anode for Na- and K-Ion batteries: A theoretical study

Abstract

Theoretical predictions on structural, electronic and transport properties of pristine and alkali-doped strontium stannate (SrSnO3) were made using density functional theory and force field methods. Results of electronic structure computations show that a doping of alkali-ion (Li+, Na+ and K+) into SrSnO3 induces the apparition of extra energy bands on the valence and conduction bands and small translation of the valence and conduction band limits. This is more accentuated in K+-ion doped samples with lower energy gap. Defect energetics computations reveal a low energetic cost associated the alkali incorporation mechanism proposed in this work. Such a mechanism provides us with an intermediate first discharge reaction to describe the delithiation process. Results on alkali ion transport properties in interstitially doped nanocrystalline SrSnO3 samples reveal lower diffusion activation energies of 0.25, 0.28 and 0.44 eV and diffusion coefficient at 25 °C of 9.6, 2.9 × 10−11 and 4.8 × 10−13 cm2s−1 for Li-, Na- and K-doped samples, respectively. These predicted properties bring in new evidence to stimulate a consideration of strontium stannate for use as an alternative anode, in particular for both Na- and K-ion batteries.