Optimizing Electrode/Electrolyte Interphases and Li‐Ion Flux/Solvation for Lithium‐Metal Batteries with Qua‐Functional Heptafluorobutyric Anhydride

Abstract

The safety and electrochemical performance of rechargeable lithium‐metal batteries (LMBs) are primarily influenced by the additives in the organic liquid electrolytes. However, multi‐functional additives are still rarely reported. Herein, we proposed heptafluorobutyric anhydride (HFA) as a qua‐functional additive to optimize the composition and structure of the solid electrolyte interphase (SEI) at the electrode/electrolyte interface. The reduction/oxidation decomposition of the fluorine‐rich HFA facilitate uniform inorganic‐rich SEI and compact cathode electrolyte interphase (CEI) formation, which enables stable lithium plating during charge and suppresses the dissolution of transition‐metal ions. Moreover, HFA optimizes the Li‐ion solvation for stable Li plating/stripping and serves as the surfactant to enhance the wettability of the separator by the electrolyte to increase Li‐ion flux. The symmetric Li∥Li cell with 1.0 wt % HFA electrolyte had an excellent cycling performance over 340 h at 1.0 mA cm−2 with a capacity of 0.5 mAh cm−2 while the Li∥NCM622 cell maintained high capacity retention after 250 cycles and outstanding rate performance even at 15 C.

Li2CO3/LiF‐Rich Heterostructured Solid Electrolyte Interphase with Superior Lithiophilic and Li+‐Transferred Characteristics via Adjusting Electrolyte Additives

“…In addition, the unstable SEI will also induce uneven ionic diffusion and Li deposition, which would result in uncontrolled dendrite growth and poor electrochemical performance. [9][10][11] Therefore, high-quality SEI is highly desired for superior LMBs.Recently, extensive efforts have been devoted to stabilizing Li anode by engineering a robust SEI mainly through electrolyte formulation [12][13][14][15][16] and artificial SEI. [17][18][19][20] However, the role of the structures and components of SEI has long been debated, and the transport mechanism of Li + ions in the SEI is still not well understood.…”

“…Recently, extensive efforts have been devoted to stabilizing Li anode by engineering a robust SEI mainly through electrolyte formulation [12][13][14][15][16] and artificial SEI. [17][18][19][20] However, the role of the structures and components of SEI has long been debated, and the transport mechanism of Li + ions in the SEI is still not well understood.…”

A Facile Surface Passivation Method to Stabilized Lithium Metal Anodes Facilitate the Practical Application of Quasi‐Solid‐State Batteries

“…The improved wettability is in favor of even distribution of the electrolyte and Li ion. [72][73][74] In addition, for further understanding the actual situation of the artificial SEI layer on the improvement of the lithium deposition interface, in situ optical microscopy characterization of the Li-Li battery was performed to study the interface changes and lithium dendrite growth in these two anode materials (Figure 1d,e). After cycling for 15 min at 0.5 mA cm −2 , large amounts of chaotically distributed lithium dendrites were formed on the surface of the bare Li anode, while the surface of the LFBF anode is uniformly deposited with lithium and almost no lithium dendrites are produced.…”

Separator Wettability Enhanced by Electrolyte Additive to Boost the Electrochemical Performance of Lithium Metal Batteries

“…Recently, Ma's group conducted a detailed research and discussion on the study of separator wettability [14]. They employed heptafluorobutyric anhydride (HFA) as a multifunctional additive to modify the commercial electrolyte (1 M LiPF 6 in EC/DMC 1:1).…”