Computational Design of New Magnesium Electrolytes with Improved Properties

Abstract

In this work, we use computational design to examine 15 new electrolyte salt anions by performing chemical variations and mutations on the bis(trifluoromethane)sulfonamide (TFSI) anion. On the basis of our calculations, we propose two new anions as potential candidates for magnesium energy-storage systems, which are evolved from TFSI with the substitution of sulfur atoms in TFSI and the modification of functional groups. The applicability of these new anion salts is examined through comprehensive calculations using both first-principles as well as benchmarked classical molecular dynamics. We elucidate the important properties of these anions, including the electrochemical stability window, chemical decomposition, preferred solvation structure, diffusion coefficient, and other dynamical properties for 15 rationally designed molecules. Two of the designed anions are found to successfully avoid the vulnerability of TFSI during ion-pair charge-transfer reactions while retaining comparable or better performance of other properties. As such, our work provides, to our knowledge, the first theoretically designed electrolyte salt for contemporary multivalent batteries and provides guidance for the synthesis and testing of novel liquid electrochemical systems.

Fluorinated Aryl Sulfonimide Tagged (FAST) salts: modular synthesis and structure–property relationships for battery applications

“…Energy & Environmental Science DG assoc , versus the relative 23 Na chemical shifts as well as the ion conductivities of DME solutions containing several FAST salts at 0.1 M experimentally obtained at 25 1C (Fig. 7b).…”

“…[48][49][50] The TFSI anion is well known for being an ''innocent'' anion with weak interactions with metal ions. 50 To compare our FAST salts with TFSI and evaluate the extent of ion dissociation, the anion-cation interaction strengths for our FAST salts were determined by 23 Na NMR. 50,51 The sodium salts were prepared as 0.1 M solutions in nitromethane with 0.25 M NaClO 4 in DMSO as the internal standard.…”

“…20,21 Moreover, encouraging results have been reported on utilizing TFSI salts in sodium-air batteries 22 and multivalent energy storage systems such as magnesium batteries. 23 Though great progress has been made on the development of solid polymer electrolytes wherein LiTFSI is dissolved in an aprotic polymer matrix of poly(ethylene oxide) (PEO), the transference number of Li + in such materials is typically as low as 0.2, 24,25 which leads to polarization at the battery electrodes and deleterious effects such as dendrite growth and limited power delivery. 4,[26][27][28] One strategy to improve the Li + (or Na + in sodium batteries) transference number involves anchoring the anions to a polymeric backbone, making the cation the only mobile ion (i.e., single-ion conducting polymer electrolytes).…”

Anode-Electrolyte Interfaces in Secondary Magnesium Batteries

“…Qu et al preformed a computational study in order to examine the feasibility of various ''modified TFSI'' type electrolytes. 47 This approach presents a new and intriguing route to develop new suitable salts for magnesium secondary batteries.…”

Computational screening of anode materials for potassium‐ion batteries

“…Recently, material explorations using computational screening have assisted in the identification of promising candidates using high-throughput material databases based on first principles calculations. [24][25][26][27] Promising materials were identified for coatings at the interface of solid electrolytes, 28,29 cathode materials, [30][31][32][33][34] anode materials, 35,36 solid-state electrolyte, 37 Mg battery electrolytes, 38 photo-catalysts, 39 and fuel cell electrodes. 40 Our earlier works also presented novel and promising anode materials for SIBs using high-throughput screening.…”