Regulation of SEI Formation by Anion Receptors to Achieve Ultra‐Stable Lithium‐Metal Batteries

Abstract

Despite high specific capacity (3860 mAh g−1), the utilization of Li‐metal anodes in rechargeable batteries are still hampered due to their insufficient cyclability. Herein, we report an anion‐receptor‐mediated carbonate electrolyte with improved performance and can ameliorate the solid electrolyte interphase (SEI) composition comparing to the blank electrolyte. It demonstrates a high average Coulombic efficiency (97.94 %) over 500 cycles in the Li/Cu cell at a capacity of 1 mAh cm−2. Raman spectrum and molecular modelling further clarify the screening effects of the anion receptor on the Li+‐PF6− ion coupling that results in the enhanced ion dynamics. The X‐ray photoelectron spectroscopy (XPS) distinguishes the disparities in the SEI components of the developed electrolyte and the blank one, which is rationalized by the molecular insights of the Li‐metal/electrolyte interface. Thus, we prepare a 2.5 Ah prototype pouch cell, exhibiting a high energy density (357 Wh kg−1) with 90.90 % capacity retention over 50 cycles.

Lithium‐Ion Batteries Containing Surfactants for the Protection of Graphite Anode against the Passivation Layer Byproducts

“…It should be noted that the low efficiency in the first cycle stems from the SEI formation. [11] For the case of LiFOS, the initial specific capacity is lower than the other two additives (344, 325 vs. 317 mAh g À 1 , Table 2) and marginally higher than the standard electrolyte (330 vs. 338 mAh g À 1 at cycle 15, Table 2). In the presence of the three SEI-related salts, the capacities are close to each other, lingering between 275 and 280 mAh g À 1 , lower than the other inves-tigated additives as are the coulombic efficiencies (e. g., LiFOS in the presence of LiOH or Li 2 O achieve coulombic efficiencies of 98.65 and 96.54 %, respectively).…”

“…The electrolyte properties dictate how fast the cell reaction can proceed (i. e., power density) and how many times a battery can be charged and discharged (cyclability). [7,11] Additives are an essential electrolyte component along with salt and solvent. [12] The ideal amount of the selected additive likely depends on its function in the cell and the amount needed to obtain the desired effect (especially at the interface of electrode/electrolyte) without having a significant negative influence on other properties impacting the performance.…”

Anionic Activity in Fast-Charging Batteries: Recent Advances, Prospects, and Challenges

“…Concerning the aforementioned quandary, tremendous research has been conducted on the structure, − composition, − and mechanical properties − of electrode–electrolyte interfaces to develop a stable, homogeneous, and kinetically favorable interfacial film for fast-charging batteries with high safety and reliability. Since the inductive effect of polyanions can be utilized to change the M–O covalency in the bulk phase to develop polyanion cathodes with high stability and safety, the design of polyanion-based ion-conductor coatings on the electrode surface as the artificial interfacial layer is expected to reduce the side reactions and accelerate transport kinetics for fast-charging applications compared to the traditional organic-rich SEI. − …”

Accessing the Primary Solid–Electrolyte Interphase on Lithium Metal: A Method for Low‐Concentration Compound Analysis

“…This SEI is formed spontaneously due to the contact of bare and reactive lithium with the electrolyte. In prior reports, this phase has been given different names, including “primary”, [26] “primitive”, [18] or “initial” SEI [27–29] . In this study, it will be referred to as “primary SEI”.…”