Discipline: Chemistry and Chemical Sciences
Subcategory: Chemistry (not Biochemistry)
Antonio L. Fraticelli-Cartagena - University of Puerto Rico at Cayey
Co-Author(s): Rachel Davidson, Texas A&M University; Sarbajit Banerjee, Texas A&M University
Electrochemical energy storage systems, in particular, lithium-ion batteries (LIBs) have pervaded the small electronics market and are steadily inching towards high energy and power density applications, such as electric vehicles and grid energy storage. Unfortunately, the inadequate energy densities afforded by current lithium-ion batteries are a major impediment to increased utilization of renewable energy technologies. Improvements in gravimetric and volumetric energy densities can potentially be realized through use of metallic anodes. However, metallic lithium is plagued by a high propensity towards dendritic growth and thus its utilization in anodes has been plagued by safety concerns. Magnesium batteries have been considered as an alternative to Li batteries, given the high natural abundance of magnesium and potential for higher volumetric energy densities arising from the divalent charge of Mg2+. Perhaps the most promising advantage derives from the many reports claiming that Mg is impervious to dendrite growth, which would facilitate the use of metallic Mg as an anode. We demonstrate using in situ monitoring of Mg—Mg cells under galvanostatic conditions from Grignard reagents the formation of Mg dendrites, which refutes conventional wisdom regarding the non-dendrite-forming nature of magnesium. The deposits have been examined as a function of deposition parameters such as current density and concentration. The experiments show that an increase in current density leads to an increase in the driving force of the reaction, which allows for faster kinetics of growth. In addition, we have observed that changes in the concentration of the MeMgCl causes changes in the morphology and the homogeneity of the deposition. Increasing the concentration results in more linear growth (needle-like) or organized branching as opposed to the more fractal-like growth seen at lower concentrations. The electrodeposited Mg has been characterized by electron microscopy, powder X-ray diffraction, and X-ray photoemission spectroscopy. The growth regimes correspond to distinctive Damkohler numbers reflecting variations in chemical reactivity (adhesion coefficients and charge transfer) and transport (self-diffusion along different crystallographic directions and across steps/kinks). Further investigations of growth mechanisms will be focused on exploring the effects of other deposition parameters such as surface ligands.
Funder Acknowledgement(s): Funding was provided by the National Science Foundation under DMR 1627197.
Faculty Advisor: Sarbajit Banerjee, firstname.lastname@example.org
Role: In this research I conducted all the experiments and developed my findings. Using video microscopy, I was able to monitor the effects of current density and concentration on magnesium electrodeposition. I also characterized the magnesium growths using powder X-ray diffraction.