An Extremely Simple Method for Protecting Lithium Anodes in Li‐O₂ Batteries

Abstract

Rechargeable Li-O batteries have aroused much attention for their high energy density as a promising battery technology; however, the performance of the batteries is still unsatisfactory. Lithium anodes, as one of the most important part of Li-O batteries, play a vital role in improving the cycle life of the batteries. Now, a very simple method is introduced to produce a protective film on lithium surface via chemical reactions between lithium metals and 1,4-dioxacyclohexane. The film is mainly composed of ethylene oxide monomers and endows Li-O batteries with enhanced cycling stability. The film could effectually reduce the morphology changes and suppress the parasitic reactions of lithium anodes. This simple approach provides a new strategy to protect lithium anodes in Li-O batteries.

A Versatile Halide Ester Enabling Li‐Anode Stability and a High Rate Capability in Lithium–Oxygen Batteries

“…Figure 2shows the results of galvanostatic cycling studies using symmetric Li j Li cells.T he cell in 1.0 m LiTFSI-TEGDME electrolyte becomes hardly sustainable when the current density increases to 5o r1 0mAcm À2 (Figure 2b,c) due to the non-uniform Li deposition at high current densities. [10,11] Thef irst support for our hypothesis is supplied by the SEM measurements:F igure 3a,b show the Li metal in the electrolyte without TCCF after 15 cycles and the surface is rough. Thel owered polarization voltage and enhanced stability of the LMA observed here can be attributed to the introduction of the halide ester.T he electrolyte with TCCF appears to form au niform and highly conductive SEI on the surface of the Li metal, facilitating stable Li stripping and deposition at the start of the cycling measurements.…”

“…Thel owered polarization voltage and enhanced stability of the LMA observed here can be attributed to the introduction of the halide ester.T he electrolyte with TCCF appears to form au niform and highly conductive SEI on the surface of the Li metal, facilitating stable Li stripping and deposition at the start of the cycling measurements. [10,11] Thef irst support for our hypothesis is supplied by the SEM measurements:F igure 3a,b show the Li metal in the electrolyte without TCCF after 15 cycles and the surface is rough. In contrast, the surface of the Li metal in the electrolyte with 2% TCCF is flat (Figure 3d,e).…”

“…[8,9] Theuniform solid-electrolyte interphase (SEI) film on the Li metal surface is crucial in the stabilization of Li properties and compensates for volumetric and morphological changes during repetitive Li charge/ discharge. [10,11] During the past decades,v arious approaches have been applied to fabricate as table and uniform SEI on the surface of Li anodes,s uch as the pretreatment of Li metal, [12] electrolyte additives, [13] and superconcentrated electrolytes. [14] In these investigations,t he stable SEI layer was constructed in situ on the surface of the LMA with the assistance of electrolyte additives such as LiNO 3 ,c esium cations,a nd ionic liquids,w hich is considered as imple and effective strategy.…”

A Multi‐Ion Strategy towards Rechargeable Sodium‐Ion Full Batteries with High Working Voltage and Rate Capability

“…These calculated results were further verified by the X-ray photoelectron spectroscopy (XPS) measurements.A s illustrated in Figure 2f,t he fully charged Sn exhibited two new peaks with lower binding energy (483.9 eV and 483.3 eV) compared with the pristine Sn. [15] Ther ate capability of SMIBs was tested within the potential window of 2.0-4.8 V. Figure 3a illustrates typical galvanostatic charge/discharge curves at different current rates from 5t o3 0C.O nly as light charge/discharge plateau separation was observed, suggesting small electrode polarization. [15] Ther ate capability of SMIBs was tested within the potential window of 2.0-4.8 V. Figure 3a illustrates typical galvanostatic charge/discharge curves at different current rates from 5t o3 0C.O nly as light charge/discharge plateau separation was observed, suggesting small electrode polarization.…”

“…Meanwhile,t he Li 1s peak at 54.9 eV (Figure 2g)and Na 1s peak at 1072.6 eV (Figure 2h) can be assigned to Li-Sn and Na-Sn alloy,r espectively, because of their higher binding energy than their metallic phase (54.6 eV for lithium and 1071.4 eV for sodium). [15] Ther ate capability of SMIBs was tested within the potential window of 2.0-4.8 V. Figure 3a illustrates typical galvanostatic charge/discharge curves at different current rates from 5t o3 0C.O nly as light charge/discharge plateau separation was observed, suggesting small electrode polarization. As shown in Figure 3b,t he discharge capacity exhibited good stability during every ten cycles with average values varied from 93.6 mAh g À1 at 5C to 81.5 mAh g À1 at 30 C, showing high capacity retention of 87 %.…”