Lithium‐Oxygen Batteries: Stabilization of Li Metal Anode in DMSO‐Based Electrolytes via Optimization of Salt–Solvent Coordination for Li–O₂ Batteries (Adv. Energy Mater. 14/2017)

Abstract

In article number https://doi.org/10.1002/aenm.201602605, a new approach to enhance the cycling stability of Li‐O2 batteries with dimethyl sulfoxide (DMSO) based electrolyte is developed by Wu Xu, Ji‐Guang Zhang, and co‐workers. It is found that the LiTFSI‐3DMSO electrolyte exhibits an optimal concentration in which only most stable TFSI−–Li+–(DMSO)3 complexes exist but Li+–(DMSO)4 solvates and free DMSO solvent molecules are absent. This electrolyte significantly enhances the stability of both Li metal anodes and carbon‐based airelectrode. The finding on the fundamental stability of the electrolyte in the absence of free‐solvent against the chemical and electrochemical reactions can also be used to enhance the stability of other electrochemical systems.

Aqueous-Eutectic-in-Salt Electrolytes for High-Energy-Density Supercapacitors with an Operational Temperature Window of 100 °C, from −35 to +65 °C

“…According to previous works using Raman spectroscopy, this shift indicates a transition from H 2 O-solvated DMSO complexes in the eutectic mixture without LiTFSI to Li + -solvated DMSO complexes, in the form of a 4-fold coordination structure with or without the TFSI – anions in the first coordination shell (e.g., (TFSI – ) a Li + (DMSO) b , with a + b = 4). Actually, previous studies by XPS on a highly concentrated electrolyte based on LiTFSI in DMSO with a molar ratio of 1:3 corroborated the formation of TFSI – Li + (DMSO) 3 complexes . The formation of Li + -solvated DMSO complexes with solvent molecules in the first coordination shell was further corroborated by us using 17 O NMR spectroscopy (Figure ).…”

“…The solution structures of highly concentrated solutions of LiTFSI ,− and similar salts (e.g., LiFSI) , have been well described in previous works for both WIS and SIS electrolytes. In both cases, as the concentration of salt increases, the solvent molecules are outnumbered by cations or anions susceptible to solvation so that ionic species such as solvent-separated ion pairs (SSIPs), contact ion pairs (CIPs), and ionic aggregates (AGGs) begin to coexist.…”

“…Herein, we describe the preparation of AEIS electrolytes using the eutectic mixture of DMSO:H 2 O (e.g., in a molar ratio of 1:2) to solubilize LiTFSI over a 1.1–8.8 molality range so as to obtain the following electrolytes: DMSO:H 2 O LiTFSI1.1 , DMSO:H 2 O LiTFSI2.9 , DMSO:H 2 O LiTFSI4.4 , DMSO:H 2 O LiTFSI6.6 , and DMSO:H 2 O LiTFSI8.8 . LiTFSI was chosen as the salt because of its high solubility in both solvents and high stability against hydrolysis. ,, Meanwhile, the molality range was selected according to the definition of a WIS system (i.e., salt outnumbering the solvent by both weight and volume) so that we could compare DMSO:H 2 O-based systems both below and within the AEIS regime (e.g., at ca. 3.5 m in this case; see Figure S1).…”

“…LiTFSI was chosen as the salt because of its high solubility in both solvents and high stability against hydrolysis. 7,16,17 Meanwhile, the molality range was selected according to the definition of a WIS system (i.e., salt outnumbering the solvent by both weight and volume) 18 so that we could compare DMSO:H 2 O-based systems both below and within the AEIS regime (e.g., at ca. 3.5 m in this case; see Figure S1).…”

A Ga–Sn liquid metal-mediated structural cathode for Li–O2 batteries

“…[3][4][5][6] However, challenges remain regarding the further application of LOBs, e.g., the poor cyclability induced by cathode passivation and electrolyte decomposition, fast Li depletion and safety concerns due to the corrosion and dendritic growth of Li. [7][8][9][10] Considerable efforts have been devoted to the optimization/protection of Li anodes [11][12][13][14][15] and electrolytes, [16][17][18] aiming to extend the cycle life of LOBs. From the perspective of whole battery operation, the sluggish kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) decreased the formation and decomposition of solid lithium peroxide (Li2O2) (2 Li + + O 2 + 2e − ↔ Li 2 O 2 , E 0 = 2.96 V), 19 thus leading to many technical issues, i.e., cathode passivation with irreversible damage to the cathode associated with the capacity loss, accumulation of discharge products and by-products (LiOH and/or Li2CO3, etc.).…”