Interplay between structure, properties, relaxations and conductivity mechanism in new electrolytes for secondary Magnesium batteries
Abstract
This proposal seeks to demonstrate the viability of secondary magnesium batteries by overcoming current barriers that prevent the practical use of this energy storage technology. Presently, several issues do not allow to exploit the potential of Mg-based batteries including: (1) difficulties associated with the transport of Mg2+ cations in the electrolyte; (2) a narrow electrochemical window of current electrolytes used in Mg-ion batteries; and (3) the growth of an insulating passivation film on the surface of the Mg anode. New high-performance electrolytes must be developed to address these drawbacks and must undergo detailed theoretical and experimental studies to elucidate the complex interplay between chemical composition, thermomechanical properties, structure, and electrical response. Only with this fundamental understanding it will be possible to tailor the synthesis of electrolytes exhibiting facile transport of Mg2+ and a broad electrochemical window. In the second part of this proposal, the developed electrolytes will address in a unique and innovative way the formation of the passivation layer on the surface of the Mg anode. In our approach, the passivating organo-Mg species on the surface of the anode become ÒactiveÓ species in the presence of mobilizing chemical agents (e.g. P2S5) in the galvanic processes associated with battery charge and discharge. These new ÒactiveÓ species will then act as charge carriers by activating the surface of the Mg anode through the removal of the passivation layer. This will allow us to exploit the unique characteristics of Mg chemistry with a new level of control of the redox processes at the electrode/electrolyte interface. The proposed electrolytes will operate through the concurrent mobilization of Mg cationic species, and metal-anionic species (typically introduced as AlCl3). The electrolytes will be developed based on polar organic solvents, ionic liquids, along with 2D and 3D polymeric systems. The electrolytes will undergo an extensive physicochemical characterization to determine crucial features including: chemical composition; thermal properties; and structure. Furthermore, high-level density functional theory (DFT) calculations will be undertaken to: i) elucidate the structure of the species found in the electrolytes and their mutual interactions; and ii) enhance the design of the matrix hosting the electrolyte. Nuclear magnetic resonance (NMR) measurements will elucidate: i) the relaxations of the nanodomains present into the electrolytes; ii) the diffusion coefficients of active species; and iii) the coordination interactions. Finally, our unique know-how in broadband electrical spectroscopy (BES) will allow for the detailed clarification of the electrical response of the electrolytes, providing a fundamental molecular-level description of the long-range charge migration mechanism. ÒEx situÓ electrochemical studies will be aimed at: i) determining the transport number of the electrolytes; and ii) elucidating the features of the electrochemical interfaces between the proposed electrolytes and the electrodes of the galvanic cell. These studies will be carried out by a variety of techniques including: i) cyclic voltammetry (CV); ii) electrochemical impedance spectroscopy (EIS); iii) linear sweep voltammetry (LSV); iv) galvanostatic cycling; and v) potentiostatic deposition. Finally, the assembly of coin cells including the proposed electrolytes will provide a benchmark for the assessment of the proposed galvanic systems in terms of specific energy, energy density, rate capability, cycle life, and safety. ÒPost-mortemÓ investigations on the functional components will clarify the effects of the doping with Òself-polishingÓ species on the long-term cycling of the battery. The technology researched in this project will reveal itself as significant in the development of energy storage solutions, in particular, for portable electronics and transportation applications.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 07, 2021
- Source ID
- W911NF2110347
Entities
People
- Vito Di Noto
Organizations
- Army Contracting Command
- United States Army
- University of Padua