Theoretical pulse charge for the optimal inhibition of growing dendrites
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MRS Advances © 2018 Materials Research Society DOI: 10.1557/adv.2018.97
Theoretical pulse charge for the optimal inhibition of growing dendrites Asghar Aryanfar*†, Daniel J. Brooks†, William A. Goddard III† *
Engineering Faculty, Bahçeşehir University, Istanbul, Turkey 34349, Email: [email protected]
†Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
ABSTRACT
Dendritic growth during charging period is one of the main barriers for the rechargeablity of conventional batteries. Additionally this phenomenon hinders the utilization of high energy density metal candidates by limiting the safety and allowable operating condition for these devices. We address the role of square wave pulse on the growth dynamics of dendrites in the continuum scale and large time periods by formulating an analytical criterion. Our dimension-free analysis permits the application our results to a variety of electrochemical systems in diverse scales.
INTRODUCTION: Rechargeability has been one of the main challenges of conventional batteries, which directly affects their stability, safety and amount of utilized material. One of the main barriers for the reversible elecrodeposition is the formation of highly porous whiskers, called dendrites. [1] Although the graphite electrode in the lithium ion battery has a considerable porosity, these microstructures still grow on its surface significantly. The amount and rate of growth exacerbates when replaced with alternative high-energy metals, with packed-structure. In particular lithium metal is arguably one of the most promising anode candidate materials for use in high-energy and high-power density rechargeable batteries. [2] Possessing the lowest density and smallest ionic radius, lithium has a very high gravimetric energy density (
0.53g.cm3 ).
Furthermore
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lithium is the most electropositive metal ( E
0
3.04 vs SHE), therefore coupling
with any other cathode compound, it will likely provide the highest possible voltage, making it suitable for high-power applications such as electric vehicles.[3] The prominent issue with the lithium comes from its very low surface energy, leading to the formation of thermodynamically favorable branched dendrites during electrodeposition during and after each charge period. [4] The accelerating amorphous structures can occupy a large volume in the cell, possibly could reach the cathode and short the cell. Dendrites can also detach from their thinner necks through electrodissolution during subsequent discharge period. Researchers have investigated how dendrites growth depends on such factors as current density,[5] electrode surface morphology[6, 7] and impurities [8, 9], solvent and electrolyte chemical composition [10, 11], electrolyte concentration [12], powde
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