Solvation Structure with Enhanced Anionic Coordination for Stable Anodes in Lithium‐Oxygen Batteries

Abstract

Li-O 2 batteries have garnered much attention due to their high theoretical energy density. However, the irreversible lithium plating/stripping on the anode limits their performance, which has been paid little attention. Herein, a solvation-regulated strategy for stable lithium anodes in tetraethylene glycol dimethyl ether (G4) based electrolyte is attempted in Li-O 2 batteries. Trifluoroacetate anions (TFA À ) with strong Li + affinity are incorporated into the lithium bis(fluorosulfonyl)imide (LiTFSI)/G4 electrolyte to attenuate the Li + -G4 interaction and form anion-dominant solvates. The bisalt electrolyte with 0.5 M LiTFA and 0.5 M LiTFSI mitigates G4 decomposition and induces an inorganic-rich solid electrolyte interphase (SEI). This contributes to decreased desolvation energy barrier from 58.20 to 46.31 kJ mol À 1 , compared with 1.0 M LiTFSI/G4, for facile interfacial Li + diffusion and high efficiency. It yields extended lifespan of 120 cycles in Li-O 2 battery with a limited Li anode (7 mAh cm À 2 ). This work gains comprehensive insights into rational electrolyte design for Li-O 2 batteries.

Build a High‐Performance All‐Solid‐State Lithium Battery through Introducing Competitive Coordination Induction Effect in Polymer‐Based Electrolyte

“…This interaction can be indirectly demonstrated by the electrostatic potential (ESP). It is calculated that the ESP (Figure 5f) of the S=O bonds in TFSI − is more negative (red area), which is the region of negative charge concentration and more inclined to interact with cations or Lewis acidic site [56] . In this process, Li + and Cs + coordinate with TFSI − simultaneously, contributing to a “competitive coordination” effect.…”

Interfacial chemistry regulation using functional frameworks for stable metal batteries

“…The conventional organic-rich SEI is usually inhomogeneous and low ionic conductive, which leads to nonuniform Li deposition. 24,70,71 It is effective to regulate the ionic conductivity of SEI through additives, polymeric conductors, or ceramic particle modification. 72–74 However, the obtained SEI still has the problems of low modulus and insufficient ionic conductivity.…”

“…19–21 The main challenge in electrolyte regulation is modifying solvation structures for cation desolvation and SEI formation on electrode–electrolyte interface. 22–24 However, this strategy is limited to the protection of the top surface of electrodes, especially at high current densities. The repeated expansion and contraction of metal anodes during charging/discharging break SEI integrity and lead to the continuous consumption of electrolytes.…”

Build a High‐Performance All‐Solid‐State Lithium Battery through Introducing Competitive Coordination Induction Effect in Polymer‐Based Electrolyte

“…It is calculated that the ESP (Figure 5f) of the S=O bonds in TFSI À is more negative (red area), which is the region of negative charge concentration and more inclined to interact with cations or Lewis acidic site. [56] In this process, Li + and Cs + coordinate with TFSI À simultaneously, contributing to a "competitive coordination" effect. Therefore, the region of 730-760 cm À 1 in the Raman spectra (Figure 5b), which is sensitive to the overall expansion and contraction behavior of the TFSI À anion, [39] confirms that the "bidentate coordination" (a kind of special CIP) and AGG of TFSI À are indeed formed in PP-LL-C compared to PP-LL at present.…”