Modeling the nucleation and growth of Li at metal current collector/LiPON interfaces

The all-solid-state-lithium battery (SSLB) is a key technology to use Li metal anode with a theoretical capacity of 3860 mAhg^-1 while suppressing the growth of Li dendrites. We present the model of Li nucleation on a solid-state electrolyte with metal current collector (CC)/lithium phosphorous oxynitride (LiPON) interfaces as the nucleation sites. We also observe the initial stage of Li growth and following Li dissolution using an in-situ scanning electron microscope (SEM) technique. The Li nucleation overpotential increases with increasing the Young's modulus of the CC. Also, the achievable Li particle sizes drastically increase with the Young's modulus of the CC. Our calculations show agreements with the experimental results and reveal that tensile stresses in a CC generate 10^-1-10⁰ GPa pressures on Li nuclei. Those pressures are three orders of magnitude larger than the ultimate tensile strength of bulk Li.