Molecular simulation of lithium metal deposition

PAZ SERGIO ALEXIS; PAULA VALENTINA SARAVIA; ANDREA C. CALDERÓN

Belgrado

Congreso; 71th Annual Meeting of the International Society of Electrochemistry.; 2020

International Society of Electrochemistry

Lithium metal is considered the ultimate anode for energy-storage systems for its extremely high theoretical specificcapacity (3860 mAh g−1), the lowest redox potential (−3.040V vs the standard hydrogen electrode) and a low gravimetricdensity (0.534 g cm−3) [1]. However the main issueassociated with this electrode is the growth of metal dendrites,also known as high surface area lithium (HSAL), duringcharge/discharge cycles. Therefore, there is a great interest inthe study of the mechanism of HSAL formation and the effectof the different variables that takes places. Of course, a finalgoal is the possibility to tune these variables to control theformation of HSAL. Such control remains elusive probablybecause it requires an important feedback between theory andexperiments. Molecular simulations could help to improve thisfeedback, altought the construction of an ad-hoc model thatconnects the simulations parameters with the experimentalmeassures is required. We have developed a computer modelbased on that of Mayers et. al. [2] to simulate the HSALgrowth. One side of the simulation box, say the bottom, isconsidered an ideal electrode where lithium ions can reduceand deposite. In the opposite side, the simulation box isconnected to a constant density reservoir of lithium ions thatmaintain the system at a constant chemical potential. The motion of lithium ions is integrated using theLangevine equation that, together with the reservoir, set the system in the NμT thermodinamicalensamble. The deposition is a random event with probability P that may occur when a lithium ion approchto the implicit electrode or to a previosuly deposited metal atom. This probability P can be connected tothe experimental cell overpotential. In this work we present the effects that different P values have in theresulting HSAL morfologies. The study of other process like dissolution or surface difusion within thismodel, and furhter extensions, are discuss.[1] Yang, H., Guo, C., Naveed, A., Lei, J., Yang, J., Nuli, Y., & Wang, J. (2018). Recent progress andperspective on lithium metal anode protection. Energy Storage Materials, 14(January), 199?221.https://doi.org/10.1016/j.ensm.2018.03.001[2] Mayers, M. Z., Kaminski, J. W., & Miller, T. F. (2012). Suppression of Dendrite Formation via PulseCharging in Rechargeable Lithium Metal Batteries. The Journal of Physical Chemistry C, 116(50),26214?26221. https://doi.org/10.1021/jp309321w