Electric field induced formation of a two-dimensional adatom gas on cryogenic Li surfaces

Intense electrostatic fields, such as those able to break bonds and cause field-ion emission, can fundamentally alter the behavior of atoms at and on the surface. Using density functional theory calculations on the Li (110) surface under high electrostatic fields, we identify a critical field strength at which surface atoms occupying a kink site become thermodynamically unstable against adatom formation. This mechanism leads to the formation of a highly concentrated two-dimensional adatom gas on the surface. Moreover, the applied field reverses the stability of preferred adsorption sites, enabling barrierless diffusion of lithium atoms even well below the threshold required for field evaporation. The here identified mechanisms offer a unified explanation for experimental observations in atom probe tomography and for understanding high electric field phenomena at battery interfaces and electrochemical environments, especially formation of Li rich dendrites.