Low‐Polarization Lithium–Oxygen Battery Using [DEME][TFSI] Ionic Liquid Electrolyte

Abstract

The room‐temperature molten salt mixture of N,N‐diethyl‐N‐(2‐methoxyethyl)‐N‐methylammonium bis(trifluoromethanesulfonyl) imide ([DEME][TFSI]) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt is herein reported as electrolyte for application in Li–O2 batteries. The [DEME][TFSI]–LiTFSI solution is studied in terms of ionic conductivity, viscosity, electrochemical stability, and compatibility with lithium metal at 30 °C, 40 °C, and 60 °C. The electrolyte shows suitable properties for application in Li–O2 battery, allowing a reversible, low‐polarization discharge–charge performance with a capacity of about 13 Ah g0pt-12.84526ptcarbon2.84526pt in the positive electrode and coulombic efficiency approaching 100 %. The reversibility of the oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) is demonstrated by ex situ XRD and SEM studies. Furthermore, the study of the cycling behavior of the Li–O2 cell using the [DEME][TFSI]‐LiTFSI electrolyte at increasing temperatures (from 30 to 60 °C) evidences enhanced energy efficiency together with morphology changes of the deposited species at the working electrode. In addition, the use of carbon‐coated Zn0.9Fe0.1O (TMO‐C) lithium‐conversion anode in an ionic‐liquid‐based Li‐ion/oxygen configuration is preliminarily demonstrated.

An Aluminum/Graphite Battery with Ultra‐High Rate Capability

“…Speed mixing (15 minutes) followed by sonication (5 minutes) was repeated 3 times until a homogeneous dispersion was obtained. [22,48] To confirm the reliability of the electrode preparation process, which has already been used for lithium-air batteries, [47,49] the same procedure was used for the preparation of a LiFePO 4 (LFP) electrode (the LFP was kindly supplied by ALEEES) with a loading of 5-6 mg cm À2 . Finally, disks of 10 mm diameter were cut and dried under vacuum at 110 8C overnight ( Figure S1a).…”

Reducing Capacity and Voltage Decay of Co‐Free Li1.2Ni0.2Mn0.6O2 as Positive Electrode Material for Lithium Batteries Employing an Ionic Liquid‐Based Electrolyte

“…These mostly consist in either employing organic solvents as additives or operating the cell at elevated temperature. [22][23][24] Mixing different ILs with LiPF 6 and ethylene carbonate/dimethyl carbonate (EC/DMC) was shown to result in improved cycling stability compared to pure carbonate-based electrolytes. [13] Increasing the IL content leads to a reduced initial irreversible capacity loss and higher coulombic efficiency in the first cycle.…”

Wettability Engineering for Studying Ion Transport in 2D Layered Materials

“…This ionic liquid was widely used in the field in its pure form for electrolyte gating purposes, but also binary salt mixtures with LiTFSI have been explored for Li–O 2 batteries. [ 39 ] No difference was observed in static contact angle after drop‐casting this electrolyte on commercial monolayer graphene (Graphenea, 300 nm SiO 2 /Si substrates), both with and without a small addition of LiTFSI (10 wt%).…”

“…The latter serves as a proxy for [DEME][TFSI]‐based binary salt mixtures such as [DEME][TFSI]‐LiTFSI. [ 38,39 ] We present guiding principles for the integration of these electrolytes with micrometer‐scale 2D material devices, the electrolyte‐free parts of which remain entirely uncovered. In a next step we fabricate a wettability engineered micro two‐compartment cell, inspired from the analysis of hydrogen permeation through solid metal, and use it to control and probe the room‐temperature diffusion of Li in few‐layer graphene.…”