title: Thermal relaxation of lithium dendrites.
abstract: The average lengths λ̅ of lithium dendrites produced by charging symmetric Li(0) batteries at various temperatures are matched by Monte Carlo computations dealing both with Li(+) transport in the electrolyte and thermal relaxation of Li(0) electrodeposits. We found that experimental λ̅(T) variations cannot be solely accounted by the temperature dependence of Li(+) mobility in the solvent but require the involvement of competitive Li-atom transport from metastable dendrite tips to smoother domains over ΔE(++)(R) ∼ 20 kJ mol(-1) barriers. A transition state theory analysis of Li-atom diffusion in solids yields a negative entropy of activation for the relaxation process: ΔS(++)(R) ≈ -46 J mol(-1) K(-1) that is consistent with the transformation of amorphous into crystalline Li(0) electrodeposits. Significantly, our ΔE(++)(R) ∼ 20 kJ mol(-1) value compares favorably with the activation barriers recently derived from DFT calculations for self-diffusion on Li(0)(001) and (111) crystal surfaces. Our findings suggest a key role for the mobility of interfacial Li-atoms in determining the morphology of dendrites at temperatures above the onset of surface reconstruction: TSR ≈ 0.65 TMB (TMB = 453 K: the melting point of bulk Li(0)).
authors.affiliation: Linde Center for Global Environmental Science, California Institute of Technology, Pasadena, CA 91125, USA. aryanfar@caltech.edu ajcoluss@caltech.edu.
authors.forename: Asghar
authors.initials: A
authors.lastname: Aryanfar
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Brooks
authors.forename: Agustín J
authors.initials: AJ
authors.lastname: Colussi
authors.forename: Boris V
authors.initials: BV
authors.lastname: Merinov
authors.forename: William A
authors.initials: WA
authors.lastname: Goddard
authors.forename: Michael R
authors.initials: MR
authors.lastname: Hoffmann