scholarly journals A Computational Comparison of Ether and Ester Electrolyte Stability on a Ca Metal Anode

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Diana Liepinya ◽  
Manuel Smeu
Keyword(s):  
Ethylene Carbonate ◽  
Stable Solution ◽  
Electrolyte Solutions ◽  
Ab Initio Molecular Dynamics ◽  
Excess Charge ◽  
Decomposition Products ◽  
Metal Anode ◽  
Decomposition Reactions ◽  
Charge Analysis ◽  
Dynamics Simulations

Ca-ion batteries (CIBs) have the potential to provide inexpensive energy storage, but their realization is impeded by the lack of suitable electrolytes. Motivated by recent experimental progress, we perform ab initio molecular dynamics simulations to investigate early decomposition reactions at the anode-electrolyte interface. By examining different combinations of solvent—tetrahydrofuran (THF) or ethylene carbonate (EC)—and salt—Ca(BH4)2, Ca(BF4)2, Ca(BCl4)2, and Ca(ClO4)2—we identify a variety of behavioral trends between electrolyte solutions. Next, we perform a separate trajectory with pure THF and gradually increased negative charge; despite an addition of -32e, no THF decomposition is detected. Charge analysis reveals that in a reductive environment, THF distributes excess charge evenly across its hydrocarbon backbone, while EC concentrates charge on its ester oxygens and carbonyl carbon, resulting in decomposition. Graphs of charge vs. time for both solvents reveal that EC decomposition products can be reduced by up to five electrons, while those of THF are limited to a single electron. Ultimately, we find Ca(BH4)2 and THF to be the most stable solution investigated herein, corroborating experimental evidence of its suitability as a CIB electrolyte.

scholarly journals Why Is Tetrahydrofuran a Good Solvent for Calcium Batteries? Insights From Ab Initio Molecular Dynamics Simulations

2021 ◽  
Author(s):  
Shreyas Pathreeker ◽  
Ian D. Hosein
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Design Principle ◽  
Liquid Electrolyte ◽  
Cyclic Ether ◽  
Ab Initio Molecular Dynamics ◽  
Metal Anode ◽  
Electrolyte Component ◽  
Calcium Metal ◽  
Dynamics Simulations

Calcium batteries are rapidly emerging as a potential, future energy storage technology; however, their advancement relies heavily on understanding of the liquid electrolyte component in terms of stability and interactions with a calcium metal anode. Tetrahydrofuran, a cyclic ether, is an experimentally common and promising solvent for the preparation of stable and efficient calcium electrolytes. However, insights into the reasons why are lacking, which could unveil key principles to electrolyte design. In this report, we provide a theoretical study employing ab initio molecular dynamics (AIMD) simulations of the interactions of Ca metal with the cyclic ether tetrahydrofuran (THF). The results show that the electrochemical breakdown and decomposition of THF at the Ca surface is highly orientation- and surface-site dependent, thereby significantly reducing the likelihood of its instability in a randomly organized bulk solvent. Likewise, in bulk electrolytes, its likelihood for breakdown is further diminished, in preference for coordination Ca2+ to form solvated structure. Hence, the finding that molecules require such strict conditions for their decomposition is an important selection and design principle for any solvent to prepare suitable calcium electrolytes. These findings are critical to the advancement of the calcium batteries.

scholarly journals Why Is Tetrahydrofuran a Good Solvent for Calcium Batteries? Insights From Ab Initio Molecular Dynamics Simulations

2021 ◽  
Author(s):  
Shreyas Pathreeker ◽  
Ian Hosein
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Design Principle ◽  
Liquid Electrolyte ◽  
Cyclic Ether ◽  
Ab Initio Molecular Dynamics ◽  
Metal Anode ◽  
Electrolyte Component ◽  
Calcium Metal ◽  
Dynamics Simulations

Calcium batteries are rapidly emerging as a potential, future energy storage technology; however, their advancement relies heavily on understanding of the liquid electrolyte component in terms of stability and interactions with a calcium metal anode. Tetrahydrofuran, a cyclic ether, is an experimentally common and promising solvent for the preparation of stable and efficient calcium electrolytes. However, insights into the reasons why are lacking, which could unveil key principles to electrolyte design. In this report, we provide a theoretical study employing ab initio molecular dynamics (AIMD) simulations of the interactions of Ca metal with the cyclic ether tetrahydrofuran (THF). The results show that the electrochemical breakdown and decomposition of THF at the Ca surface is highly orientation- and surface-site dependent, thereby significantly reducing the likelihood of its instability in a randomly organized bulk solvent. Likewise, in bulk electrolytes, its likelihood for breakdown is further diminished, in preference for coordination Ca2+ to form solvated structure. Hence, the finding that molecules require such strict conditions for their decomposition is an important selection and design principle for any solvent to prepare suitable calcium electrolytes. These findings are critical to the advancement of the calcium batteries.

scholarly journals Proton Transport Mechanism and Pathways in the Superprotonic Phase of M3H(AO4)2 Solid Acids from Ab Initio Molecular Dynamics Simulations

2021 ◽  
Author(s):  
Boris Merinov ◽  
Sergey Morozov
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Proton Transport ◽  
Transport Mechanism ◽  
Solid Acids ◽  
Ab Initio Molecular Dynamics ◽  
Theoretical Studies ◽  
Dynamics Simulations ◽  
Experimental And Theoretical Studies ◽  
Superprotonic Phase

The proton transport mechanism in superprotonic phases of solid acids is a subject of experimental and theoretical studies for a number of years. Despite this, details of the mechanism still...

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