Lithium–Metal Batteries Using Sustainable Electrolyte Media and Various Cathode Chemistries

Abstract

Lithium–metal batteries employing concentrated glyme-based electrolytes and two different cathode chemistries are herein evaluated in view of a safe use of the highly energetic alkali-metal anode. Indeed, diethylene-glycol dimethyl-ether (DEGDME) and triethylene-glycol dimethyl-ether (TREGDME) dissolving lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium nitrate (LiNO 3 ) in concentration approaching the solvents saturation limit are used in lithium batteries employing either a conversion sulfur–tin composite (S:Sn 80:20 w/w) or a Li + (de)insertion LiFePO 4 cathode. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) clearly show the suitability of the concentrated electrolytes in terms of process reversibility and low interphase resistance, particularly upon a favorable activation. Galvanostatic measurements performed on lithium–sulfur (Li/S) batteries reveal promising capacities at room temperature (25 °C) and a value as high as 1300 mAh g S –1 for the cell exploiting the DEGDME-based electrolyte at 35 °C. On the other hand, the lithium–LiFePO 4 (Li/LFP) cells exhibit satisfactory cycling behavior, in particular when employing an additional reduction step at low voltage cutoff (i.e., 1.2 V) during the first discharge to consolidate the solid electrolyte interphase (SEI). This procedure allows a Coulombic efficiency near 100%, a capacity approaching 160 mAh g –1 , and relevant retention particularly for the cell using the TREGDME-based electrolyte. Therefore, this work suggests the use of concentrated glyme-based electrolytes, the fine-tuning of the operative conditions, and the careful selection of active materials chemistry as significant steps to achieve practical and safe lithium–metal batteries.

Glyme-based electrolytes: suitable solutions for next-generation lithium batteries

“…Along with the initial conceptualization and pioneering studies of glyme-based electrolytes, Li–metal batteries using the most common intercalation electrodes, such as LiCoO 2 and graphite, as well as other insertion cathodes such as LiFePO 4 , were proposed with promising results, in spite of several issues which were firstly identified. 43–60 Afterwards, “high-concentration” glyme-based electrolytes have attracted a great deal of attention due to their favorable properties, and there is an intriguing dilemma on the actual nature of these mixtures, which have been described as either solvent-in-salt solutions or solvated ionic liquids (SILs). 61–82 Moreover, glyme-based electrolytes have been gaining renewed interest due to a possible suitability for the emerging high-energy lithium–sulfur (Li–S) battery, which is formed by combining a lithium–metal anode and a sulfur-based cathode.…”

Diglyme-Incorporated Gelled Polymer: An Efficient Quasi-Solid-State Electrolyte for Sodium-Ion Batteries

“…The present work is compared, in Table , with various glyme-based electrolytes existing in the literature in terms of ionic conductivity, ESW, and their performance in rechargeable battery systems. − The ionic conductivity and ESW of the present quasi-solid-state electrolyte are comparable or even higher than many liquid- and solid-state glyme-based systems. Furthermore, the performance of the developed electrolyte film in rechargeable sodium battery systems is also comparable to the batteries reported in the literature.…”

Effect of Polymer Binders with Single-Walled Carbon Nanotubes on the Electrochemical and Physicochemical Properties of the LiFePO4 Cathode

“…The studied composite cathodes delivered almost identical capacities (150−154 mA h g −1 ) (Figure 4a), which were somewhat lower as compared to the best reported LFP cathodes (160−165 mA h g −1 ). 50,51 The capacity values at a low C-rate could be increased by further optimization of the LFP synthetic procedure which was out of scope of this investigation. The cathodes formulated with SWCNTs demonstrated similar galvanostatic profiles, independent of the polymer nature.…”