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Electrolytes with high stability against both Li anode and high‐voltage cathode are critical for high‐energy and long‐cycling lithium metal batteries (LMBs). However, the free active solvents in common electrolytes are susceptible to decomposition at both Li anode and high‐voltage cathode. Although recently developed locally high‐concentration electrolytes (LHCEs) have largely restricted active solvents via Li+ coordination, the free molecules are still released upon the desolvation of Li+ at the surface of electrodes, causing continuous decomposition during long‐cycling processes. Here, a molecule competitive solvation electrolyte (MCE) is shown to stabilize high‐voltage LMBs by introducing a well‐designed and newly synthetic bipolar solvent molecule with one ion‐dissociative polar head and the other highly fluorinated nonpolar tail. The bipolar molecules competitively dissociate Li+ via weak coordination interactions, drastically reducing the ratio of active solvents in electrolytes and the detrimental decomposition at electrodes during the desolvation processes. Consequently, the MCE enables a 1.4‐Ah Li metal pouch cell with a stack energy density of 450 Wh kg−1 along with exceptional operation stability over 400 cycles (retention: 81%). Furthermore, the MCE also maintains the stable operation of a 2.5‐Ah Li‐S pouch cell with an excellent energy density of 417 Wh kg−1 for 70 cycles under practical conditions. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries using quasi-solid gel electrolytes (QSEs) have gained increasing interest due to their enhanced safety features. However, their commercial viability is hindered by low ionic conductivity and poor solid-solid contact interfaces. In this study, a QSE synthesized by in situ polymerizing methyl methacrylate (MMA) in 1,2-dimethoxyethane (DME)-based electrolyte is introduced, which exhibits remarkable performance in high-loading graphite||LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) pouch cells. Owing to the unique solvent-lacking solvation structure, the graphite exfoliation caused by the well-known solvent co-intercalation is prohibited, and this unprecedented phenomenon is found to be universal for other graphite-unfriendly solvents. The high ionic conductivity and great interfacial contact provided by DME enable the quasi-solid graphite||NCM811 pouch cell to demonstrate superior C-rate capability even at a high cathode mass loading (17.5 mg cm -2 ), surpassing liquid carbonate electrolyte cells. Meanwhile, the optimized QSE based on carbonates exhibits excellent cycle life (92.4% capacity retention after 1700 cycles at 0.5C/0.5C) and reliable safety under harsh conditions. It also outperforms liquid electrolytes in other high-energy-density batteries with larger volume change. These findings elucidate the polymer's pivotal role in QSEs, offering new insights for advancing quasi-solid-state battery commercialization., (© 2024 The Author(s). Advanced Materials published by Wiley‐VCH GmbH.)

As a promising high energy density electrode material for rechargeable batteries, lithium (Li) metal is still suffering from air/water instability due to its highly reactive nature. In addition, the Li dendrite issue in Li metal batteries needs to be resolved to ensure the safety of batteries and for wide applications. Herein, we demonstrate that a simple compact GaO x layer formed using liquid metal (LM) can act as an artificial solid electrolyte interphase to block moisture and oxygen in the air from corroding the lithium metal. Interestingly, GaO x that covered the electrode effectively inhibits Li dendrite growth in electrochemistry cycling, ensuring the safety of Li metal batteries. The exposed composite Li metal anode (exposed under ambient air with relative humidity (RA) ≈ 75% for 5 h) not only shows a superior stability (symmetrical cell) but also delivers an elevated cycling stability (>500 cycles at 0.5 and 1 C) with a sulfur@C cathode in the full-cell configuration. Our work provides a new pathway for the large-scale applications of the air/water-tolerant Li metal anode in rechargeable batteries.